Effects of dietary protein level on intestinal function and inflammation in nursery pigs

High crude protein (CP; 21% to 26%) diets fed during the first 21 to 28 d postweaning are viewed negatively because of a perceived increase in the incidence rates of diarrhea due to increased intestinal protein fermentation and/or augmented enteric pathogen burden. This is thought to antagonize nursery pig health and growth performance. Therefore, our objective was to evaluate the impact of low vs. high dietary CP on 21-day postweaned pig intestinal function. Analyzed parameters included ex vivo intestinal barrier integrity (ileum and colon), ileal nutrient transport, tissue inflammation, and fecal DM. One hundred and twenty gilts and barrows (average body weight) were randomly assigned to one of two diets postweaning. Diets were fed for 21 d, in two phases. Phase 1 diets: low CP (17%) with a 1.4% standardized ileal digestible (SID) Lys (LCP), or high CP (24%) with a 1.4% SID Lysine (HCP). Phase 2: LCP (17%) and a 1.35% SID lysine, or HCP (24%) formulated to a 1.35% SID lysine. Pig growth rates, feed intakes, and fecal consistency did not differ (P > 0.05) due to dietary treatment. Six animals per treatment were euthanized for additional analyses. There were no differences in colonic epithelial barrier function as measured by transepithelial electrical resistance (TER) and fluorescein isothiocyanate (FITC)-dextran transport between treatments (P > 0.05). Interleukins (IL)-1α, IL-1β, IL-1ra, IL-2 IL-4, IL-6, and IL-12 were not different between treatments (P > 0.05). However, IL-8 and IL-18 were higher in HCP- vs. LCP-fed pigs (P < 0.05). There were no differences in fecal dry matter (DM; P > 0.05) between treatments. In the ileum, there was a tendency (P = 0.06) for TER to be higher in HCP-fed pigs, suggesting a more robust barrier. Interestingly, glucose and glutamine transport were decreased in HCP- vs. LCP-fed pigs (P < 0.05). FITC-dextran transport was not different between treatments (P > 0.05). There were also no differences in ileal cytokine concentrations between diets (P > 0.05). Taken together, the data show that low CP does not negatively impact colonic barrier function, fecal DM, or inflammation. In contrast, ileal barrier function and nutrient transport were altered, suggesting a regional effect of diet on overall intestinal function.

Intestinal location- and age-specific variation of intraepithelial T lymphocytes and mucosal microbiota in pigs

Intraepithelial T lymphocytes (T-IELs) are T cells located within the epithelium that provide a critical line of immune defense in the intestinal tract. In pigs, T-IEL abundances and phenotypes are used to infer putative T-IEL functions and vary by intestinal location and age, though investigations regarding porcine T-IELs are relatively limited. In this study, we expand on analyses of porcine intestinal T-IELs to include additional phenotypic designations not previously recognized in pigs. We describe non-conventional CD8α⁺CD8β^- αβ T-IELs that were most prevalent in the distal intestinal tract and primarily CD16⁺CD27^-, a phenotype suggestive of innate-like activation and an activated cell state. Additional T-IEL populations included CD8α⁺CD8β⁺ αβ, CD2⁺CD8α⁺ γδ, and CD2⁺CD8α^- γδ T-IELs, with increasing proportions of CD16⁺CD27^- phenotype in the distal intestine. Thus, putative non-conventional, activated T-IELs were most abundant in the distal intestine within multiple γδ and αβ T-IEL populations. A comparison of T-IEL and respective mucosal microbial community structures across jejunum, ileum, and cecum of 5- and 7-week-old pigs revealed largest community differences were tissue-dependent for both T-IELs and the microbiota. Between 5 and 7 weeks of age, the largest shifts in microbial community compositions occurred in the large intestine, while the largest shifts in T-IEL communities were in the small intestine. Therefore, results indicate different rates of community maturation and stabilization for porcine T-IELs and the mucosal microbiota for proximal versus distal intestinal locations between 5 and 7 weeks of age. Collectively, data emphasize the intestinal tract as a site of location- and age-specific T-IEL and microbial communities that have important implications for understanding intestinal health in pigs.

Acute infection with Brachyspira hyodysenteriae affects mucin expression, glycosylation, and fecal MUC5AC

Introduction

Infection with strongly β-hemolytic strains of Brachyspira hyodysenteriae leads to swine dysentery (SD), a production-limiting disease that causes mucohemorrhagic diarrhea and typhlocolitis in pigs. This pathogen has strong chemotactic activity toward mucin, and infected pigs often have a disorganized mucus layer and marked de novo expression of MUC5AC, which is not constitutively expressed in the colon. It has been shown that fucose is chemoattractant for B. hyodysenteriae, and a highly fermentable fiber diet can mitigate and delay the onset of SD.

Methods

We used lectins targeting sialic acids in α-2,6 or α-2,3 linkages, N-acetylglucosamine (GlcNAc), α-linked L-fucose, and an immunohistochemical stain targeting N-glycolylneuraminic acid (NeuGc) to investigate the local expression of these mucin glycans in colonic tissues of pigs with acute SD. We used a commercial enzyme-linked immunosorbent assay (ELISA) to quantify fecal MUC5AC in infected pigs and assess its potential as a diagnostic monitoring tool and RNA in situ hybridization to detect IL-17A in the colonic mucosa.

Results

Colonic mucin glycosylation during SD has an overall increase in fucose, a spatially different distribution of GlcNAc with more expression within the crypt lumens of the upper colonic mucosa, and decreased expression or a decreased trend of sialic acids in α-2,6 or α-2,3 linkages, and NeuGc compared to the controls. The degree of increased fucosylation was less in the colonic mucosa of pigs with SD and fed the highly fermentable fiber diet. There was a significant increase in MUC5AC in fecal and colonic samples of pigs with SD at the endpoint compared to the controls, but the predictive value for disease progression was limited.

Discussion

Fucosylation and the impact of dietary fiber may play important roles in the pathogenesis of SD. The lack of predictive value for fecal MUC5AC quantification by ELISA is possibly due to the presence of other non-colonic sources of MUC5AC in the feces. The moderate correlation between IL-17A, neutrophils and MUC5AC confirms its immunoregulatory and mucin stimulatory role. Our study characterizes local alteration of mucin glycosylation in the colonic mucosa of pigs with SD after B. hyodysenteriae infection and may provide insight into host-pathogen interaction.

Soluble corn fiber, resistant corn starch, and protected butyrate effects on performance, gastrointestinal volatile fatty acids, and apparent total-tract digestibility of calcium and phosphorus in nursery pigs

An experiment was conducted to determine how feeding calcium (Ca)-deficient diet would affect gastrointestinal pH and volatile fatty acids (VFAs), Ca digestibility, bone mineral density (BMD), and performance in nursery pigs; and if supplementation of nondigestible oligosaccharides would affect these same parameters. In total, 240 weaned pigs (BW = 7.1 kg) were placed into 80 pens with 3 pigs/pen. The eight dietary treatments consisted of: 1) positive control (PC, 0.83% total Ca), 2) negative control (NC, 0.50% total Ca), 3 and 4) NC + 5% or 7.5% soluble corn fiber (SCF), 5 and 6) NC + 5% or 7.5% resistant corn starch (rCS), 7 and 8) NC + 0.25% or 0.50% fat-protected butyrate (pBRT). Pigs were ad libitum fed the dietary treatments for 21 d to determine average daily gain (ADG), average daily feed intake (ADFI) and gain:feed ratio (GF) with a fecal sample collected from each pen to determine Ca digestibility using acid insoluble ash as the dietary marker, with 1 pig/pen euthanized on d 21 for collection of ileal and colon contents and the left humerus. Pigs fed the NC diet had a lower colonic pH compared with pigs fed the PC (P = 0.06) but no effect on total VFA was observed (P > 0.10). Pigs fed diets containing SCF and rCS had lower colonic pH and total VFA compared to pigs fed the NC diet (P ≤ 0.05). Pigs fed diets containing pBRT had greater colonic total VFA compared to pigs fed the NC diet (P ≤ 0.07), but no difference in colonic pH was observed (P > 0.10). Pigs fed the NC diet had a greater Ca digestibility compared to pigs fed the PC (P ≤ 0.01), with no treatment to the NC having any effect on Ca digestibility compared to pigs fed the NC (P > 0.10). There was no effect of dietary Ca level on BMD and no overall addition of feeding SCF, rCS, or pBRT on BMD compared to pigs fed the NC (P > 0.10). There was no impact on pig ADG, ADFI, or GF by reducing dietary Ca by 40% (i.e., pigs fed the NC) compared to pigs fed the PC (P > 0.10). Relative to pigs fed the NC, there was no overall effect of SCF, rCS, or pBRT on ADG, ADFI, or GF (P > 0.10). In conclusion, feeding young pigs a Ca-deficient diet reduced colonic pH, increased digestibility of Ca, but had no impact on bone mineralization or overall pig performance. Supplementation of nondigestible oligosaccharides pr protected butyrate had either no effect or an inconsistent effect on colonic pH, Ca, or PHOS digestibility, bone mineralization, or overall pig performance.

Strategies to manage barn feed supply to prolong and hold late finishing pigs during a supply chain disruption

The U.S. pork production system is sensitive to supply chain disruptions, including those that can create challenges of feed delivery and feed management during the event of a foreign animal disease outbreak. Therefore, the objective was to evaluate feeding strategies during a prolonged feed availability shortage in group-housed finishing pigs and assess the impacts on pig performance. A total of 1,407 mixed-sex pigs (92 ± 11 kg BW) were randomly allocated to one of five treatments across 60 pens (N = 12 pens per treatment, 22 pigs per pen) and were blocked by initial body weight (BW) within the replicate, over a 21-d test period. Treatments were fed for 14 d (P1), and thereafter all pens returned to ad libitum access to a standard commercial diet for 7 d (P2). Treatments included: 1) Pens fed ad libitum (CON); 2) Pens fed at 1.45X ME maintenance requirement daily of CON diet (1.45X); 3) Pens fed 2X ME maintenance requirement daily of CON diet (2X); 4) Tightened feeders to the lowest setting, fed ad libitum of CON diet (CF); and 5) whole corn kernels, fed ad libitum (WC). P1 and P2 BW and feed disappearance were recorded to calculate ADG, ADFI, and G:F. Data were analyzed with pen as the experimental unit and least-squares means values reported by treatment. Compared to CON, pens fed 1.45X, 2X, CF, and WC treatments had significantly reduced P1 ADG (1.09 vs. 0.02, 0.34, 0.72, 0.41 kg/d, respectively), ADFI (3.21 vs. 1.42, 1.90, 2.49, 2.40 kg/d, respectively) and G:F (P < 0.05). During P2, ADG and G:F were increased (P < 0.05) compared to CON across all treatments. However, ADFI increased only in the 2X, CF, and WC diet from the CON (P < 0.05). Overall (days 0 to 21), all strategies attenuated BW, ADG, and ADFI (P < 0.01) compared to CON. However, G:F was only reduced (P < 0.01) in 1.45X and WC, but not 2X and CF (P > 0.05) compared to CON. In conclusion, all strategies explored could extend feed budgets. Even though these strategies were successful, increased BW variability was reported with more restrictive strategies. Further, adverse pig behaviors and welfare implications needs to be considered in adopting any restrictive feeding strategy.

Evaluation of digestively resistant or soluble fibers, short- and medium-chain fatty acids, trace minerals, and antibiotics in nonchallenged nursery pigs on performance, digestibility, and intestinal integrity

Three experiments (EXP) were conducted to determine the effect of feed additives on performance, intestinal integrity, gastrointestinal volatile fatty acids (VFA), and energy and nutrient digestion in nonchallenged nursery pigs. In EXP 1, 480 pigs (6.36-kg body weight, BW) were placed into 96 pens with 5 pigs/pen, and allotted to 1 of 10 dietary treatments: 1) negative control containing no feed additive (NC), 2) NC + 44 mg chlortetracycline and 38.5 mg tiamulin/kg diet (CTsb), 3) NC + 5% resistant potato starch (RSpo), 4) NC + 5% soluble corn fiber (SCF), 5) NC + 5% sugar beet pulp (SBP), 6) NC + 0.30% fatty acid mix (FAM), 7) NC + 0.10% phytogenic blend of essential oils and flavoring compounds (PHY), 8) NC + 50 mg Cu and 1,600 mg zinc oxide/kg diet (CuZn), 9) NC + 5% resistant corn starch (RScn), and 10) NC + 0.05% β-glucan (BG) for 28 d. There was no impact of dietary treatment on BW gain or feed intake (P ≥ 0.22). Pigs fed diets containing SCF, CTsb, and RSpo resulted in microbial community differences compared to pigs fed the NC (P < 0.05). In EXP 2, 48 barrows (12.8 kg BW) were selected at the end of EXP 1 and fed the same dietary treatments they had previously received: 1) NC, 2) NC + 5% RScn, 3) NC + 5% SCF, and 4) NC + FAM for 8 d. There was no effect of feeding diets containing RScn, SCF, or FAM on in vivo intestinal permeability (P ≤ 0.21). Ileal or colon pH, concentrations of VFA did not differ due to dietary treatment (P ≥ 0.36), but pigs fed diets containing FAM resulted in a greater butyric acid concentration in the cecum compared to pigs fed the NC (P ≤ 0.05). In EXP 3, 156 pigs (6.11 kg BW) were placed into 52 pens with 3 pigs/pen and allotted to 1 of 4 dietary treatments arranged in a factorial manner: 1) NC, 2) NC + 5% RSpo, 3) NC + 0.30% FAM, and 4) NC + 5% RSpo + 0.30% FAM for 24 d. Feeding pigs diets containing RSpo did not affect BW gain (P = 0.91) while pigs fed diets containing FAM grew improved BW gain (P = 0.09). Colonic butyric acid concentrations were greater in pigs fed diets containing RSpo (P = 0.03), while pigs fed diets containing FAM exhibited reduced total VFA concentrations (P = 0.11). The results indicate that supplementing diets with digestively resistant but fermentable fibers, short- and medium-chain fatty acids, or antibiotics do not have a consistent effect, positive or negative, on markers of intestinal integrity or barrier function, intestinal VFA patterns, ATTD of energy and nutrients, or on pig performance.

207 Awardee Talk: The Impact of Disease on Nutrient and Energy Intake and Utilization to Support Lean Tissue Accretion in Growing Pigs

Optimal lean tissue production can be severely compromised by health challenges in nursery-finisher pig production systems. Common pig immune challenges in the U.S. can come from pathogens such as Porcine Reproductive and Respiratory Syndrome virus, Lawsonia intracellularis, Mycoplasma spp, Coccidia, pathogenic E. coli and Porcine Epidemic Diarrhea virus. The subsequent disease that can manifests in response to these pathogens can lead to mitochondrial damage, impaired capacity to generate sufficient ATP for homeostasis, limited energy availability (exacerbated by disease hypophagia) and compromised cell survival and organ function. Collectively, skeletal muscle hypertrophy is reduced in a trade off to support the energetic and protein synthesis needs of immune system response. In growing pigs, we have reported that sub-clinical and clinical enteric and respiratory disease can significantly impact intestinal function, feed intake, lean tissue accretion and feed efficiency. This has a major economic impact for pork producers, pig welfare and wellbeing. While significant advances in molecular and quantitative genetics, clinical diagnostics and virology have been made to enhance poor performance and heath, we are still unsure on how to best feed and manage poor-health pigs. By understanding the longitudinal impact pathogens on digestibility, metabolism, protein accretion and feed efficiency, insights into nutritional requirements and management strategies can be developed to improve poor-health pig production. This paper will discuss the molecular and physiological impact of sub-clinical and clinical disease on nutrient and energy intake and utilization to support lean tissue accretion in growing pigs.

Dietary Pharmacological Zinc and Copper Enhances Voluntary Feed Intake of Nursery Pigs

The objective of the three experiments herein were to characterize the effect of pharmacological zinc and copper concentrations on nursery pig feed intake, stomach ghrelin, energy and nutrient digestibility, and mineral retention in post-weaned pigs. In Expt. 1, 300 weaned pigs were allotted across three dietary treatments (n = 10 pens/treatment) and fed in two diet phases (P1 and P2) lasting 7 and 14 days, respectively. Treatments were: (1) Control diet with no pharmacological minerals in P1 and P2, CON; (2) CON + 3,000 mg/kg Zn and 200 mg/kg Cu (P1), no pharmacological minerals in P2, ZC-CON; and (3) CON + 3,000 mg/kg Zn and 200 mg/kg Cu (P1), CON + 2,000 mg/kg Zn and 200 mg/kg Cu (P2); ZC. Over the 21-day test period, ZC pigs had 15% higher ADG and 13–24% ADFI compared to the CON and ZC-CON pigs (P &lt; 0.05). ZC-CON and ZC pig daily feed intakes were 29 and 73% higher by day 5 and 7 post-weaning, respectively, compared to the CON pigs (P &lt; 0.0001). However, removing pharmacological minerals in P2 abruptly decreased ZC-CON daily feed intake within 24 h to similar intakes as the CON compared to the ZC pigs (0.17, 0.14, and 0.22 kg/d, respectively, P &lt; 0.05). Dietary pharmacological minerals increased stomach fundus ghrelin-positive cells than CON pigs at day 7 (P = 0.005) and day 21 (P &lt; 0.001). However, fasting plasma total and acyl-ghrelin concentrations did not differ from a control in response to zinc oxide daily drenching (Expt. 2). Expt. 3 showed that zinc and copper to have moderate to low retention; however, pharmacological zinc and copper diets increased zinc (P &lt; 0.05) and copper retention (P = 0.06) after 28 days post-weaning compared to control pigs. Pharmacological zinc and copper did not improve digestible energy, metabolizable energy or nitrogen balance. Altogether, dietary pharmacological zinc and copper concentrations improve growth rates and mineral retention in nursery pigs. This improved performance may partially be explained by increased stomach ghrelin abundance and enhanced early feed intake in newly weaned pigs fed pharmacological concentrations of zinc and copper.

PSVIII-11 The Impact of Dietary Crude Protein and Non-Starch Polysaccharidase Inclusion on Nursery Pig Performance

Our objective was to evaluate the effect of crude protein (CP) levels and non-starch polysaccharide (NSP) enzyme on nursery pig performance. 792 mixed sex pigs (6.2 ± 0.12 kg BW) were randomly allotted across 6 dietary treatments (12 pens/treatment) using a 3x2 factorial. Three base diets, with or without NSPase, were fed in 3 phases (10, 11 and 21 d, respectively). Base diet and Lys per phase were: 1) 17% low CP with of 1.40, 1.35, 1.30% SID Lys (LCP1.4); 2) 24% high CP, 1.40, 1.35, 1.30% SID Ly (HCP1.4); and 3) 17% CP, 1.20, 1.15, 1.10% SID Lys (LCP1.2). Pig weights and feed disappearance were recorded to calculate ADG, ADFI, and G:F within phase and overall. Pen fecal scores and day 21 fecal dry matter (DM) were evaluated. Data were analyzed with pen as the experimental unit and least square means reported by treatment. Overall and within phase, no diet by enzyme interactions were reported for ADG, ADFI and G:F (P &lt; 0.05). Within diet, HCP1.4 had greater overall ADG compared with LCP1.4 and LCP1.2 (0.42, 0.36, 0.35 kg/d respectively, P &lt; 0.0001). Overall ADFI tended to differ between the LCP1.4, HCP 1.4 and the LCP1.2 treatments (0.60, 0.61 and 0.57 kg/d, respectively, P = 0.066). Overall G:F was greater in the HCP1.4 compared with LCP1.4 and LCP1.2 pigs (0.69, 0.61 and 0.62, respectively, P &lt; 0.0001). Fecal scores and 21-d fecal DM did not differ (P &gt; 0.05) in LCP1.4, HCP1.4 and LCP1.2 pigs (32, 28 and 31% DM, respectively) and with or without enzyme (32 and 29% DM, respectively, P = 0.300). Overall, compared with no enzyme, enzyme was not different (P &gt; 0.05) for ADG (0.37 vs 0.39 kg/d), ADFI and G:F. In conclusion, low CP diets did not enhance pig performance or alter fecal consistency.

163 Peak-Infection Application of Increased SID Lysine:ME Diets Does Not Improve Disease Challenge Growth Performance

Increasing dietary SID Lys:ME augments growth performance of Porcine Reproductive and Respiratory Syndrome virus (PRRSV) challenged pigs when diets with greater SID Lys concentrations are in place at time of infection. Our objective was to evaluate the delayed implementation of increased SID Lys:ME diets post PRRSV challenge on pig performance. 491 grower pigs (45.8 ± 7.4 kg BW) were assigned to 1 of 3 dietary strategies (n = 16 pens/treatment, 10-11 pigs/pen). All pigs received a common diet from day post inoculation (dpi) -14 to dpi 21 (P1), that met SID Lys:ME recommendations. From dpi 21 to 77 (market body weight), dietary treatments were implemented in 2 phases (P2 and P3). The 2 dietary treatments were 2.23 g/Mcal (100%), 2.56 g/Mcal (115%), 2.90 g/Mcal (130%) in P2; and 1.92 g/Mcal (100%), 2.21 g/Mcal (115%), 2.49 g/Mcal (130%) in P3. On dpi 0, all pigs were inoculated with PRRSV. Pig BW, feed disappearance and feed efficiency were determined in each phase. Data were analyzed with pen as the experimental unit in a complete randomized design. During P1, ADG, ADFI, or G:F did not differ (P &lt; 0.05). In P2 and P3, ADG, ADFI, or G:F did not differ between the 100%, 115% and 130% treatments (P &gt; 0.10). Overall, ADG (0.90, 0.90 and 0.92 kg/d, P = 0.44) and ADFI (2.61, 2.57 and 2.57 kg/d, P = 0.48) did not differ between the 100%, 115% and 130% treatments, respectively. However, overall G:F was significantly higher for the 130% compared with the 100% and 115% treatments (0.36 versus 0.34 and 0.35, respectively; P = 0.021). Mortality was similar across treatments (P = 0.717). In conclusion, delayed feeding of diets with increased SID Lys:ME post infection was not beneficial to pig performance indicating this diet strategy needs to be in place near time of disease challenge.

PSV-12 Evaluation of Iron Source and Level on Nursery Pig Performance and Blood Hemoglobin Concentrations

The objective of this study was to evaluate effects of dietary iron (Fe) source and concentration on nursery pig performance and blood hemoglobin concentrations. A total of 960 newly weaned, mixed sex pigs (5.7 ± 0.40 kg BW) were allotted to 4 dietary treatments using a complete randomized design (24 pens/treatment, 10 pigs/pen). All pigs were fed a 3-phase corn-soybean meal-based diet. The 4 diets were: 1) 100 ppm Fe from iron sulfate; 2) 100 ppm Fe from an iron-amino acid complex (Fe-AA; ProPath Fe 150), 3) 50 ppm Fe from Fe-AA and 4) 25 ppm Fe from Fe-AA. Pigs were weighed on day 0, 7, 21 and 42, and feed disappearance measured to calculate ADG, ADFI and G:F within phase and overall. Blood hemoglobin was assessed on d 0, 21 and 35. Pen was considered the experimental unit and all data were analyzed using the mixed procedure of SAS with treatment as a fixed effect. Iron treatment did not alter pig performance (ADG, ADFI and G:F) in phase 1, 2 or 3 (P &gt; 0.05). Overall, ADG was similar between treatments (0.46, 0.45, 0.45 and 0.44 kg/d, respectively, P &gt; 0.05). Similarly, overall ADFI was similar between treatments (0.61, 0.60, 0.58 and 0.62 kg/d, respectively, P = 0.31). Overall 42-day G:F did not differ between treatments (P &gt; 0.05). Blood hemoglobin concentrations (g/dL) showed a quadratic response over day post-weaning (P &lt; 0.001); however, no treatment or treatment by day interaction were reported (P &gt; 0.05). Altogether, these data demonstrate that feeding 25-100 ppm of Fe-AA provided similar performance to 100 ppm Fe from an inorganic source. Additionally, pigs did not have altered hemoglobin levels or become Fe deficient when diets were supplemented with Fe-AA at levels below NRC requirement.

102 Reduced Caloric Intake Increases the Incidence Rate of Gastric Ulcers in Growing Pigs

Our objective was to evaluate effects of a disease feed intake pattern on gastric ulcerations. Eighty mixed sex pigs (27.9 ± 1.45 kg BW) were allotted to individual pens and 2 treatments using a complete randomized design. All pigs were fed a 450 µm ground corn-soybean meal diet. Period 1 (d 0-28), all pigs were fed ad libitum. In period 2 (d 29-42), 40 pigs were fed daily based on their individual body weight (averaging 1.45x maintenance) to mimic a disease feed intake (RF) profile. The remaining pigs stayed on ad libitum feed (Ad). Pigs were weighed at d 0, 28 and 42, and feed disappearance measured to calculate ADG, ADFI and G:F within period. At d 42, all pigs were euthanized, stomach pH recorded, and stomach ulcerations scored (0-3 scale, with 0 being normal). Performance, pH and ulceration frequency data were analyzed with pig as the experimental unit and the fixed effect of feeding level. Performance was not different in period 1 (P &lt; 0.05). Compared with the Ad, RF pigs had lower ADG (1.10 vs 0.24 kg/d, P &lt; 0.0001), ADFI (2.15 vs 0.85 kg/d, P &lt; 0.0001) and G:F (0.51 vs 0.28, P &lt; 0.0001) in period 2. Stomach pH was greater in the RF compared with the Ad pigs (P &lt; 0.001). A greater percentage of Ad pig stomachs scored normal to mild on pars oesophagea ulcerations (85 vs 62%), while a greater percentage of RF pigs had a maximum score compared with the Ad (38 vs 15%, respectively). RF pigs had a higher frequency of severe stomach body ulcerations (score 3) compared with the Ad (20.5 vs 15.0%, respectively). These data suggest that a disease feed intake pattern exacerbates the incidence of gastric ulcerations in grower pigs fed a fine micron ground corn.

146 Evaluation of Phase Feeding and Lysine Source and Level on Nursery Pig Performance

Phase feeding is employed to optimize lysine levels to meet pigs' requirements. Therefore, our objective was to evaluate the effect of varying lysine levels and phase lengths in nursery pigs. Four-hundred freshly weaned pigs (5.53 ± 0.96 kg BW) were randomly selected and assigned to 1 of 4 dietary treatments (n = 10 pens/treatment, 10 pigs/pen). The treatments for phase (P) 1-3 were: 1) High synthetic amino acids (1.60, 1.45, 1.33% SID Lys, respectively; HighSyn), 2) High soybean meal (1.60, 1.45, 1.33 % SID Lys, respectively; HighSBM), 3) Low Lys (1.30, 1.50, 1.45% SID Lys, respectively; Low), and 4) Continuous 1.42 % SID Lys (Con). Phase 1, 2 and 3 consisted of 7, 14 and 21 d, respectively. Body weights and feed disappearance were recorded on d 0, 7, 21 and 42, and ADG, ADFI and G:F calculated within phase and overall (0-42 d). All data were analyzed using a complete randomized design with pen as the experimental unit. P1 ADG was 42% greater in the HighSBM compared with the other treatments (P = 0.030), while ADFI tended to be 23% higher (P = 0.089). In P2, ADG was 21% higher in the HighSBM compared with the HighSyn pigs, with the other treatments being intermediate (P = 0.012). ADFI tended to be higher in the HighSBM pigs compared with the other treatments in P2 (P = 0.087). No significant performance differences were reported in P3. Overall, HighSMB had higher ADG compared with Con, Low and HighSyn pigs (0.360, 0.338, 0.338 and 0.311 kg/d, respectively; P = 0.007), while overall ADFI and G:F tended to be lower in HighSyn compared with the other treatments (P &lt; 0.10). In conclusion, high synthetic Lys reduced performance, while continuous single-phase feeding offered equal performance to that of higher Lys curves achieved via soybean meal inclusion.

243 Assessment of Modified Corn Protein as a Protein and Energy Source for Nursery Pigs

Our objective was to evaluate modified corn protein (MCP) as a protein and energy source in nursery pig diets. A total of 198 weaned pigs (6.25 ± 0.95 kg BW) were assigned across 18 pens (11 pigs/pen) and 2 dietary treatments using a complete randomized design. Pigs were fed in 3 phases consisting of 7, 14, and 21 d respectively. In phases 1 and 2, diets included: 1) Control or 2) 10% MCP, while all pigs were on a common phase 3 diet. Diets were formulated to be iso-caloric with SID Lys at 1.45, 1.40 and 1.35% for phases 1, 2 and 3 respectively. Pigs were weighed and feed disappearance measured to calculate ADG, ADFI and G:F within phase and overall. At the end of phase 2, fecal samples were collected for determination of apparent total tract digestibility coefficients (ATTD) for dry matter, energy and nitrogen. Pen was considered the experimental unit and all data were analyzed using the mixed procedure of SAS with treatment as a fixed effect. In phases 1 and 2, ADG, ADFI and G:F did not differ between Control and MCP treatments (P &gt; 0.05). Similarly, performance did not differ between treatments in phase 3 (P &gt; 0.05). Overall, end BW (25.7 vs. 25.3 kg), ADG (0.42 vs. 0.44 kg/d), ADFI (0.58 and 0.61 kg/d) and G:F (0.71 vs. 0.70) did not differ (P &gt; 0.05) between the Control and MCP treatments, respectively. However, compared with the Control, phase 2 ATTD coefficients for dry matter (80.6 vs. 78.2%), nitrogen (77.5 vs. 75.2%) and gross energy (79.7 vs. 76.9%) were significantly reduced in the MCP treatment (P &lt; 0.05). In conclusion, MCP provided equal nursery pig performance when used as an alternative protein and energy source in diet formulations despite lower ATTD.

PSVIII-14 Zinc Oxide Augments Early Nursery Pig Feed Intake

Pharmacological concentrations of zinc (Zn) are commonly fed in the nursery to benefit early post-weaning performance and reduces scours. Therefore, our objective was to determine the effect of pharmacological Zn on post-weaning pig daily feed intake and performance. Three-hundred weaned pigs (5.7 ± 1.03 kg BW) were selected and allotted to 1 of 3 dietary treatments (n = 10 pens/treatment, 10 pigs/pen). Diets were fed over 2 phases (phase 1: d 0-7, phase 2: d 8-21) and consisted of: 1) Control diet with no growth promoting additives, CON; 2) CON + 3,000 ppm Zn and 200 ppm Cu (phase 1), no pharmacological minerals in phase 2, ZC1; and 3) CON + 3,000 ppm Zn and 200 ppm Cu (phase 1), CON + 2,000 ppm Zn and 200 ppm Cu (phase 2); ZC2). Bodyweights were collected at d 0, 7, and 21. Feed disappearance was recorded daily from d 0-14, and within phase. In phase 1, ZC1 and ZC2 pigs had 29% greater feed consumption compared with the CON pigs (0.09, 0.09, 0.07 kg/d; P &lt; 0.0001). Within 2 d of phase 2 diet change, feed intake of the ZC1 pigs sharply decreased to the same level of the CON pigs, while ZC2 pigs consumed 29% more (P &lt; 0.05). In phase 1, ZC1 and ZC2 pens had increased ADG compared with CON pigs (P &lt; 0.001). In phase 2, ADG was 14% greater in the ZC2 compared with ZC1 and CON pigs (P = 0.023). Overall, ADG was 15% greater in the ZC2 pigs and ADFI was 13 and 24% higher than ZC1 and CON pens, respectively (P &lt; 0.05). In conclusion, early post-weaning feed intake was augmented with pharmacological levels of Zn. These data suggest that pharmacological Zn potentially enhances voluntary feed intake regulation in pigs.

PSVIII-2 Evaluation of the Effects of a Stimbiotic and Fiber Source on Nursery Pig Performance

The objective was to evaluate the effects of feeding a stimbiotic, Signis (AB Vista), and fiber source, sugar beet pulp or wheat bran, on nursery performance. Pigs (n = 480; 5.87±1.10 kg) were assigned to treatments in a 2 x 3 factorial arrangement of Stimbiotic (0 or 100 mg/kg) and Fiber Source (control, sugar beet pulp, or wheat bran). For phase 1, wheat bran and sugar beet pulp were added at 6.0% and 3.5%, respectively. For phase 2, wheat bran and sugar beet pulp were added at 10% and 6.0%, respectively. There were 8 pens containing 10 pigs per treatment group. A 2-phase feeding program lasting 3 weeks each was used. Performance was monitored for 6 weeks. Fecal scores were recorded, and fecal samples were collected to determine apparent total tract nutrient (ATTD) digestibility. Full value pigs (FVP) were determined by subtracting mortality and removals from total number placed. Pen gain was calculated as difference of sum of BW at d 42 minus sum of BW at d 0. Data were analyzed by ANOVA using the fit model platform in JMP. Significance was accepted at P ≤ 0.05 and trends at P &lt; 0.10. Phases 1 and 2 ADG, ADFI, gain:feed or d42 BW did not differ between treatment groups. There were effects of Stimbiotic and Fiber Source on FVP as there were increased FVP (P &lt; 0.05) with Stimbiotic and decreased FVP (P &lt; 0.05) for pigs fed wheat bran. Pen gain tended to increase (P = 0.06) in pigs fed Stimbiotic and was decreased (P &lt; 0.05) for pigs fed wheat bran. Mean fecal scores were not affected by Fiber Source, but tended (P = 0.07) to be reduced by Stimbiotic. Stimbiotic tended (P ≤ 0.09) to increase ATTD of dry matter and energy. In conclusion, feeding a stimbiotic increased FVP, while feeding wheat bran decreased FVP. Further research is needed to explore the effects of fiber source in nursery diets and how it interacts with Stimbiotic.

162 Investigating Strategies to Manage Feed Supply Chain Disruptions on Grow-Finish Pigs

In the likelihood of a foreign animal disease outbreak, the U.S. pork industry may face supply chain disruptions, including those to feed delivery. Therefore, our objective was to evaluate feeding strategies to prolonged feed availability in group housed finishing pigs and assess impacts on pig performance. 1,407 mixed sex pigs (92±11 kg BW) were blocked by initial average BW to pens and assigned to 1 of 5 treatments (n =12 pens/treatment, 22 pigs/pen) over a 21-d test period. Treatments were fed for 14 d (P1) and thereafter all pens returned to ad libitum access to a standard commercial diet for 7 d (P2). Treatments included: 1) Pens fed ad libitum (CON); 2) Pens fed at 1.45x ME maintenance requirement daily (1.45x); 3) Pens fed 2x ME maintenance requirement daily (2x); 4) Tightened feeders to lowest setting, fed ad libitum (Closed); and 5) Whole corn kernels, fed ad libitum (Corn). The P1 and P2 BW and feed disappearance were recorded to calculate ADG, ADFI, and G:F. Data were analyzed with pen as the experimental unit and least squares means values reported by treatment. Compared with CON, 1.45x, 2x, Closed and Corn treatments significantly reduced P1 ADG (1.09 vs 0.02, 0.34, 0.72, 0.41 kg/d, respectively), ADFI (3.21 vs. 1.42, 1.90, 2.49, 2.40 kg/d, respectively) and G:F (P &lt; 0.05). During P2, ADG and G:F were both increased (P &lt; 0.05) compared with CON across all treatments. However, ADFI increased only from the CON in the 2x, Closed and Corn diets (P &lt; 0.05). Overall (d 0-21), all strategies attenuated BW, ADG and ADFI (P &lt; 0.0001) compared with CON. However, G:F was only reduced (P &lt; 0.01) in 1.45x and Corn, but not 2x and Closed (P &gt; 0.05) from the CON. In conclusion, implementing management strategies to conserve feed maintained marginal pig growth.

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101 Evaluation of Vitamin D on Performance and Bone Mineral Density in Finishing Pigs

The objective of this study was to evaluate the vitamin D3 (vitD) and 25-hydroxy vitamin D (25-OHD) requirements for finisher pig performance and bone density. Seventy-two pigs (62 ± 11.1 kg BW) were allotted to 36 pens (n = 2 pigs/pen) and across 4 dietary treatments (n = 9 pens/trt) for 51 d. Corn-soybean meal mash diet treatments were: 1) Diet containing 75 IU/kg vitD; 2) Diet containing 150 IU/kg vitD (NRC requirement); 3) Diet containing 750 IU/kg vitD; and 4) As 1 plus 0.0125% 25-OHD to achieve total diet equivalent of 750 IU/kg vitD. Pigs were weighed and feed disappearance recorded at the start and end of the study to calculate ADG, ADFI and G:F. Serum 25-OHD concentrations were determined on d 42. On d 51, one pig per pen was euthanized and bone mineral density determined on the rib, tibia and fibula. Data were analyzed as a complete randomized design with pen as the experimental unit. Overall, ADG did not differ between treatments 1 through 4 (1.26, 1.31, 1.34, 1.27 kg/d, respectively (P &gt; 0.05). Further, ADFI did not differ between treatments (P &gt; 0.05). However, G:F tended to increase as dietary vitD concentrations increased (0.34, 0.36, 0.37 and 0.35, respectively, P = 0.068). Rib, fibula and tibia bone mineral density did not differ between treatments (P &gt; 0.05). Serum 25-OHD concentrations were 9.9, 11.9, 23.3 and 36.6 ng/mL for treatments 1-4, respectively (P &lt; 0.001). In conclusion, vitamin D3 deficiency was not achieved with treatment 1 in finishing and all treatments had equal pig performance and bone mineral density. Further, 0.0125% 25-OHD provided equal performance and bone density to 750 IU/kg of vitamin D3.

Innovative strategies for managing swine welfare during the COVID-19 pandemic in Iowa

Coronavirus Disease 2019 (COVID-19) was declared a global pandemic on March 11, 2020 by the World Health Organization and its impact on animal agriculture in the United States was undeniable. By April, COVID-19 resulted in the simultaneous closure or reduced operations of many meat processing plants in the upper Midwest, leading to supply chain disruptions. In Iowa, the leading pork production and processing state, these disruptions caused producer uncertainty, confusion, and stress, including time-sensitive challenges for maintaining animal care. The Iowa Resource Coordination Center (IRCC) was quickly created and launched by the Iowa Department of Agriculture and Land Stewardship (IDALS). The IRCC included public representation from the Iowa Pork Producers Association (IPPA), Iowa Pork Industry Center (IPIC), and Iowa State University Extension and Outreach, and private partners including producers, veterinarians, and technical specialists. Supporting swine welfare, the IRCC provided information on management strategies, dietary alterations to slow pig growth, alternative markets, on-farm euthanasia, and mass depopulation under veterinary oversight. In a crisis, Iowa created a model that reacted to producers’ pragmatic, mental and emotional needs. This model could be quickly replicated with an introduction of foreign animal disease.

Porcine epidemic diarrhea virus infection induces endoplasmic reticulum stress and unfolded protein response in jejunal epithelial cells of weaned pigs

Porcine epidemic diarrhea virus (PEDV) infection leads to diarrhea and subsequently to decreased feed efficiency and growth in weaned pigs. Given that few studies have addressed the host-virus interaction in vivo, this study focused on endoplasmic reticulum (ER) stress and unfolded protein response (UPR) in jejunal epithelial cells during PEDV infection. Eight-week-old pigs (n = 64) were orally inoculated with PEDV IN19338 strain (n = 40) or sham-inoculated (n = 24) and analyzed for PEDV viral RNA shedding using reverse transcription-quantitative polymerase chain reaction and for viral antigen within enterocytes using immunohistochemistry (IHC). ER stress was analyzed in a subset of 9 PEDV-inoculated pigs with diarrhea, detectable viral RNA, and viral antigen (PEDV-immunopositive pigs). Compared with control pigs, PEDV-immunopositive pigs had a reduced ratio of villus height to crypt depth in the jejunum (P = .002, n = 9 per group), consistent with intestinal injury. The protein levels of ATF6, IRE1, PERK, XBP1u, ATF4, GRP78, and caspase-3 were assessed in jejunal epithelial cells at the villus tips via IHC. Both ER stress and UPR were demonstrated in PEDV-immunopositive pigs by the increased expression of ATF6 (P = .047), IRE1 (P = .007), and ATF4 (P = .001). The expression of GRP78 (P = .024) and caspase-3 (P = .004) were also increased, indicating an accompanying increase in ER protein folding capacity and apoptosis. Overall, these results reveal that PEDV infection induces ER stress and UPR in intestinal epithelial cells of weaned pigs.

13 Innovative Strategies for Managing Swine Welfare During Natural Disasters

Coronavirus Disease 2019 (COVID-19) was declared a global pandemic on March 11, 2020, by the World Health Organization. By April 2020, COVID-19 resulted in the simultaneous closure or reduced operations of many processing plants in the upper Midwest, which quickly resulted in supply chain disruptions. Iowa is the leading pork production and processing state, and these disruptions caused producer uncertainty, confusion, and stress, including time-sensitive challenges for maintaining animal care. The Resource Coordination Center (RCC) was quickly created and launched from the Iowa Department of Agriculture and Land Stewardship. The RCC had strategic collaborations with public representation from the Iowa Pork Producers Association, Iowa Pork Industry Center, and Iowa State University Extension and Outreach, and private partners through producers, veterinarians, and technical specialists. The RCC’s mission was four-fold: (1) implement appropriate actions to ensure the health and safety of RCC members, stakeholders, and the public, (2) evaluate and reassess appropriate actions as needed for continuity of pork production operations, (3) provide information to pork producers during supply chain disruptions, and (4) maintain a safe and abundant pork supply for consumers. The command structure included Incident Commanders, Command Staff, and four Section Chiefs whom worked with their respective experts. Sections covered (1) operations, (2) planning, (3) logistics, and (4) finance and administration. As it related to animal welfare, the RCC provided information on management decisions, dietary alterations to slow pig growth, pig movement to increase living space, alternative markets, on-farm euthanasia and mass depopulation. Veterinary oversight was continually maintained. A manual was created to provide up-to-date information to inform producer decisions and aid. Although originally created for swine, the RCC also assisted poultry, cattle and sheep producers. In a crisis, Iowa created a model that reacted to producer’s pragmatic and emotional needs. This model could be replicated for any emergency by other states.

Circulating biomarkers associated with pelvic organ prolapse risk in late gestation sows

Sow mortality, as the result of pelvic organ prolapse (POP), has been increasing in the last decade in the U.S. swine industry. The objective of this study was to identify potential biological markers associated with risk of POP in sows. We hypothesized that sows differing in perineal score (PS) from PS1–PS3 (PS1—a presumed low POP risk; PS2—a presumed moderate POP risk; and PS3—a presumed high POP risk) would differ in circulatory biomarkers of inflammation and hormonal profiles. On gestation week 15, 2,864 individual sows were assigned a PS, and subsequently, 1.0%, 2.7%, and 23.4% of PS1, PS2, or PS3 sows, respectively, experienced POP. During PS assignment at days 107–116 of gestation, blood samples were collected from sows on two farms of similar genetics, feed sources, and health status. Whole blood was subjected to complete blood count (CBC) analysis (n = 212) and steroid hormones were measured in serum from a subset (n = 110) of animals assigned PS3 parity matched to PS1. Lipopolysaccharide-binding protein (LBP), tumor necrosis factor-alpha (TNF-α), haptoglobin, C-reactive protein (CRP), and creatine kinase (CK) levels were also evaluated. Complete blood count analysis revealed decreased (P ≤ 0.05) mean platelet volume (3.9%), lymphocytes (6.5%), and monocytes (7.5%) in PS3 compared to PS1 sows. Increased (P ≤ 0.02) abundance of androstenedione (13.4%), androsterone (18.2%), estrone (24.8%), and 17β-estradiol (26.2%) was observed in PS3 compared to PS1 sows. Additionally, a 25.8% increase (P = 0.04) in LBP in PS3 compared to PS1 sows was observed. Many dynamic physiological changes occur in sows during late gestation as they approach farrowing. The data presented herein demonstrate that distinct differences in concentrations of circulating biomarkers exist between late gestation sows at high or low risk for POP and may serve as a useful tool for understanding the etiology of POP and evaluation of mitigation strategies.

Evaluation of increased fiber, decreased amino acids, or decreased electrolyte balance as dietary approaches to slow finishing pig growth rates

In swine production, pig movement restrictions or packing plant closures may create the need to slow growth rates of finishing pigs to ensure they remain at a marketable body weight when packing plant access is restored. Although dietary formulations can be successful at slowing pig growth, precision is needed regarding how to best formulate diets to achieve growth rate reductions. Thus, the objective was to evaluate three dietary experimental approaches aimed at slowing growth rates in finishing pigs. These approaches consisted of either increasing neutral detergent fiber (NDF), reducing essential amino acids, or reducing the dietary electrolyte balance through the addition of acidogenic salts. A total of 94 mixed-sex pigs (72.4 ± 11.2 kg BW) across two replicates were individually penned and assigned to 1 of 8 dietary treatments (n = 11-12 pigs/treatment): 1) Control diet representative of a typical corn-soybean meal-based finisher diet (CON); 2) diet containing 15% NDF from soybean hulls (15% NDF); 3) diet containing 20% NDF from soybean hulls (20% NDF); 4) diet containing 25% NDF from soybean hulls (25% NDF); 5) diet formulated as per CON but with 50% of the soybean meal replaced with corn (89% Corn); 6) diet containing 97% corn and no soybean meal or synthetic amino acids (97% Corn); 7) diet containing 2% anhydrous calcium chloride (2% CaCl2); and 8) diet containing 4% anhydrous calcium chloride (4% CaCl2). Over 28 d, pig body weights and performance were recorded weekly. At d 28, all pigs were ultrasound scanned and switched to the CON diet to evaluate compensatory gain from d 28 to 35. Overall, increased NDF did not impact any growth performance parameter (P > 0.05). Amino acid restriction reduced average daily gain (ADG), average daily feed intake (ADFI), and gain:feed (G:F) linearly (linear P < 0.001). Similarly, ADG, ADFI, and G:F were linearly reduced with increased CaCl2 inclusion (linear P < 0.001). ADG differed during the compensatory gain period (P < 0.001), with 4% CaCl2-fed pigs having a 47% increase in ADG compared with CON-fed pigs. Conversely, 15% and 25% NDF-fed pigs had reduced ADG compared with CON-fed pigs during the compensatory gain period. Gain efficiency differed from day 28 to 35 (P < 0.001), with 4% CaCl2-fed pigs having a 36% increase in G:F compared with CON-fed pigs. Altogether, these data demonstrate that both amino acid restriction and CaCl2 inclusion are effective at slowing pig growth, albeit at greater inclusion rates.

Novel Observations of Peroxiredoxin-2 Profile and Protein Oxidation in Skeletal Muscle From Pigs of Differing Residual Feed Intake and Health Status

This study’s objective was to determine the impact of a dual respiratory and enteric bacterial health challenge on the antioxidant protein peroxiredoxin-2 (Prdx-2) profile and protein oxidation in the skeletal muscle of pigs from 2 lines that were divergently selected for residual feed intake (RFI). The hypotheses were that (1) differences exist in the Prdx-2 profile between 2 RFI lines and infection status and (2) muscle from less efficient high-RFI and health-challenged pigs have greater cellular protein oxidation. Barrows (50 ± 7 kg, N = 24) from the 11th generation of the high-RFI (n = 12) and low-RFI (n = 12) Iowa State University lines were used. Pigs (n = 6 per line) were inoculated with Mycoplasma hyopneumoniae and Lawsonia intracellularis (MhLI) on day 0 post infection to induce a respiratory and enteric health challenge. Uninoculated pigs served as controls (n = 6 per line). Necropsy was at 21 d post infection. Sarcoplasmic protein oxidation, various forms of Prdx-2, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) content were determined. Neither RFI line nor infection status significantly affected protein carbonylation. Under nonreducing conditions, MhLI pigs had a greater amount of a slower-migrating GAPDH band (P = 0.017), indicating oxidative modification. Regardless of health status, the low-RFI pigs had less total Prdx-2 (P = 0.035), Prdx-2 decamer (P = 0.0007), and a higher ratio of hyperoxidized peroxiredoxin relative to Prdx-2 (P = 0.028) than the high-RFI pigs. The increased pool of active Prdx-2 in high-RFI pigs suggests greater oxidative stress in muscle in high- versus low-RFI pigs. The increase in oxidized GAPDH seen in muscle from MhLI pigs—particularly the high-RFI MhLI pigs—may be a response to the greater oxidative stress in the high-RFI MhLI. This work suggests that antioxidant proteins are important in growth and health-challenge situations.

Lawsonia intracellularis infected enterocytes lack sucrase-isomaltase which contributes to reduced pig digestive capacity

Lawsonia intracellularis is endemic to swine herds worldwide, however much is still unknown regarding its impact on intestinal function. Thus, this study aimed to characterize the impact of L. intracellularis on digestive function, and how vaccination mitigates these impacts. Thirty-six L. intracellularis negative barrows were assigned to treatment groups (n  =  12/trt): (1) nonvaccinated, L. intracellularis negative (NC); (2) nonvaccinated, L intracellularis challenged (PC); and (3) L. intracellularis challenged, vaccinated (Enterisol^® Ileitis, Boehringer Ingelheim) 7 weeks pre-challenge (VAC). On days post-inoculation (dpi) 0 PC and VAC pigs were inoculated with L. intracellularis. From dpi 19–21 fecal samples were collected for apparent total tract digestibility (ATTD) and at dpi 21, pigs were euthanized for sample collection. Post-inoculation, ADG was reduced in PC pigs compared with NC (41%, P  <  0.001) and VAC (25%, P  <  0.001) pigs. Ileal gross lesion severity was greater in PC pigs compared with NC (P  =  0.003) and VAC (P  =  0.018) pigs. Dry matter, organic matter, nitrogen, and energy ATTD were reduced in PC pigs compared with NC pigs (P  ≤  0.001 for all). RNAscope in situ hybridization revealed abolition of sucrase-isomaltase transcript in the ileum of PC pigs compared with NC and VAC pigs (P  <  0.01). Conversely, abundance of stem cell signaling markers Wnt3, Hes1, and p27^Kip1 were increased in PC pigs compared with NC pigs (P  ≤  0.085). Taken together, these data demonstrate that reduced digestibility during L. intracellularis challenge is partially driven by abolition of digestive machinery in lesioned tissue. Further, vaccination mitigated several of these effects, likely from lower bacterial burden and reduced disease severity.

270 Evaluating Nutritional Strategies to Improve Performance of Poor Health Nursery Pigs

Nursery pigs are frequently faced with disease challenges and producers are seeking nutritional strategies to help pig performance and health. Therefore, our objective was to evaluate five dietary formulation strategies that may improve performance in poor health nursery flow pigs (confirmed Rotavirus A and hemolytic E. coli positive at d 14). A total of 431 weaned pigs (5.5 ± 1.25 kg BW) were assigned to pens (10–11 pigs/pen) and one of five diets (n = 8 pens/treatment) over a 63-day test period consisting of 4 diet phases using a complete randomized design. In phase 1 and 2, treatments were: 1) 15–25% low soybean meal (LSBM), 2) 35–45% high soybean meal (HSBM), 3) 130% increase in valine and isoleucine branched-chain amino acids (BCAA) to Lys, 4) 2.1% combination of C8, C10 and C12 medium chain fatty acids (MCFA), and 5) 20% modified oats (MO). All pigs were fed a common diet for phases 3 and 4. Within phase, all diets were isocaloric with similar SID Lys:ME. Pen was considered the experimental unit and data were analyzed with contrast statements comparing each diet against the LSBM control. Across all phases, compared to LSBM, HSBM, BCAA and MO did not alter ADG, ADFI and G:F (P &gt; 0.10). However, MCFA reduced (P &lt; 0.05) ADG in phase 1 (0.20 vs 0.16 kg) and 2 (0.45 vs 0.39 kg) and phase 2 ADFI (0.66 kg vs 0.58 kg) compared to the LSBM treatment. Overall (0–63 days), compared to the LSMB, the MCFA treatment reduced ADG (0.46 vs 0.42 kg, P = 0.004) and ADFI (0.75 vs 0.68 kg, P = 0.009). Diet did not affect mortality. These data report that MCFA attenuated nursery pig performance, while HSBM, MO and BCAA diets fed in phases 1 and 2 had no longitudinal impact on pig performance or health.

271 Investigating the Relationship Between Nursery Pig Performance and Markers of Intestinal Morphology and Integrity

Weaning induces major structural and function changes to the small intestine of pigs and they transition from milk to solid feedstuffs. Thus, the objective of this study was to determine how intestinal morphology and function markers relate to feed intake and growth rates of nursery pig. Forty-eight weaned pigs (5.63 ± 0.50 kg) were randomly selected, individually penned and fed a common diet. Pig bodyweights and feed intake were determined at d 2, 7, and 21. At each time point, 16 pigs were randomly selected and euthanized. Sections of ileum were assessed for morphology [villus height (VH), crypt depth (CD) and VH:CD] and ex vivo transepithelial resistance (TER), macromolecule permeability (FD4), and active transport of glucose and glutamine via modified Ussing chambers. Within each period (d 0–2, 0–7, and 0–21), Pearson correlations were performed between ADG, ADFI, VH, VH:CD, TER, FD4 and active transport of glucose and glutamine. At d 2 post-weaning, no correlations (P &gt; 0.05) were observed between performance and intestinal variables. By d 7, moderate positive correlations between VH and ADFI (r = 0.69, P = 0.005), VH and ADG (r = 0.68, P = 0.006) were reported. At 21 d post-weaning, moderate positive correlations were still observed for VH and ADFI (r = 0.55, P = 0.026) and between VH and ADG (r = 0.51, P = 0.042). Interestingly, ADFI and ADG tended to be negatively correlated with active glucose transport (r = -0.45, P = 0.083 and r = -0.47, P = 0.064, respectively) and active glutamine transport (r = -0.45, P = 0.083 and r = -0.46, P = 0.073, respectively). Markers of ileal integrity (TER and FD4) were not correlated with ADG or ADFI at any time point. Altogether, these data highlight the importance of intestinal morphology on early nursery pig performance.

117 Improved Growth Performance in the F1 Heterozygous Generation of an SSTR2 Knockout Model in Swine

Targeted genetic alteration provides opportunities for rapid genetic improvement in resilience, welfare and production traits. Somatostatin (SST) acts via negative feedback to regulate growth hormone (GH) activity by antagonizing GH releasing hormone via SST receptors (SSTR) located in the anterior pituitary. Our objective was to reduce the negative effect of SST in the anterior pituitary on protein accretion by reducing the number of functional copies of SSTR2 using the CRISPR/Cas9 system. We hypothesized that a reduction or elimination of SSTR2 would lead to improved growth performance. To test this hypothesis, three commercial gilts were bred with semen from a founder boar in a compound heterozygous state at the SSTR2 locus with a 1bp deletion in one allele resulting in a premature stop codon and a 3bp deletion in the other allele resulting in the loss of a single amino acid predicted to remain functional after translation. Three litters of F1 offspring were produced (n = 46) and all piglets were confirmed to be heterozygous at the SSTR2 locus with one wild type allele and the other possessing either the 1bp deletion (n = 22) or the 3bp (n = 2 4) deletion. No differences (P &gt; 0.43; n=46) in body weight (1.27±0.03 kg) across comparisons were observed at birth. At weaning (n = 36), males (6.19±0.20 kg) were heavier (P = 0.007) than females (5.41±0.19 kg), and piglets possessing a 1bp deletion (6.00±0.20 kg) were numerically heavier (P = 0.14) than 3bp deletion pigs (5.59±0.18 kg). This observation was more pronounced in males at weaning, where the males with the 1bp deletion were 13% heavier (P = 0.058) than those with the 3bp deletion. These data suggest that altering SSTR2 may be a viable genetic advancement strategy to improve growth performance in pigs. This project was supported by the Lloyd L. Anderson Professorship in Physiology at Iowa State University.

85 Vaccination Mitigates Performance Losses During a Lawsonia Intracellularis Experimental Challenge

Lawsonia intracellularis is endemic to swine herds worldwide. Currently, vaccination is one of the few strategies available to mitigate L. intracellularis. Thus, this study aimed to characterize the impact of vaccination on growth performance and disease severity during experimental challenge. Thirty-six L. intracellularis negative barrows were assigned to treatment groups as follows (n = 12/trt): 1) nonvaccinated, L. intracellularis negative (NC); 2) nonvaccinated, L intracellularis challenged (PC); and 3) L. intracellularis challenged, vaccinated (Enterisol® Ileitis, Boehringer Ingelheim) at 1 week postweaning (VAC). On days post inoculation (dpi) 0 (7 weeks post-weaned) PC and VAC pigs were inoculated with L. intracellularis. Individual feed disappearance and BW were recorded weekly and all pigs were euthanized at dpi 21. Post-inoculation, ADG was reduced in PC (P &lt; 0.001) and VAC (P = 0.001) pigs compared with NC pigs. Average daily gain was additionally reduced in PC pigs compared with VAC pigs (P &lt; 0.001). Similarly, ADFI was reduced in PC (P &lt; 0.001) and VAC (P = 0.029) pigs compared with NC pigs, and further reduced in PC pigs compared with VAC pigs (P = 0.032). Overall G:F was reduced in PC pigs compared with NC (P &lt; 0.001) and VAC (P = 0.015) pigs, which did not differ. For antibody response and fecal shedding, NC pigs remained negative. Antibody responses and fecal shedding were lower in VAC pigs compared with PC pigs (P &lt; 0.05). Ileal gross lesion severity was greater in PC pigs compared with VAC (P = 0.018) and NC (P = 0.003) pigs, which did not differ. Similarly, ileal lesion length was greater in PC pigs compared with NC (P = 0.007) and VAC (P = 0.045) pigs. Microscopic lesion severity was greater in PC pigs compared with both PC and VAC pigs (P &lt; 0.05). Taken together, these data characterize the impact L. intracellularis has on growth performance of pigs and highlight the importance of vaccination to prevent disease associated performance losses.

268 In-feed Antibiotics Elicit Intestinal Integrity Modifications Early in Post-weaning Life

The physiological mechanisms by which in-feed antibiotics improve pig growth performance are largely unknown. One proposed mode of action is improvements in intestinal integrity and function. Therefore, the objective of this study was to test the hypothesis that in-feed therapeutic and sub-therapeutic antibiotics would improve intestinal integrity and function in nursery pigs. Twenty-four weaned pigs (6.1±1.1 kg BW) were randomly allotted to individual pens and assigned one of three dietary treatments as follows (n = 8 pigs/trt): 1) control, no antibiotics (CON), 2) CON + sub-therapeutic chlortetracycline [40 ppm in feed (sCTC)], and 3) CON + chlortetracycline-tiamulin [400 ppm + 35 ppm, respectively (CTCDen)]. The study consisted of two consecutive 14 d phases. Chlortetracycline-tiamulin was only fed in phase 1, sCTC was fed in both phases. Phase 1 and 2 ADG, ADFI, and G:F were determined. After 28 d, ileal and colonic ex vivo intestinal integrity was assessed via transepithelial resistance (TER) and macromolecule flux (FD4) in modified Ussing chambers. All data were analyzed for the fixed effects of treatment and start BW as a covariate. In phase 1, compared with CON and sCTC, CTCDen tended to have greater ADG (0.28, 0.31, and 0.33 kg/d, respectively, P = 0.10) and ADFI (0.28, 0.30, and 0.35 kg/d, respectively, P = 0.09). No differences in phase 1 G:F were observed (P = 0.11). Phase 2 ADG, ADFI, and G:F did not differ (P &gt; 0.10). Further, ileal TER and FD4 did not differ (P &gt; 0.10). Colonic TER tended to be increased in sCTC compared with CON and CTCDen (78, 56, and 59 Ω/cm2, respectively, P = 0.07). Compared with CON, colonic FD4 flux was decreased in sCTC and CTCDen by 35–40% (P = 0.03). Altogether, these data indicate that in-feed antibiotics improve colon integrity early in production which may contribute to improved growth performance.

267 Evaluating the Interaction Between Nursery Diet Complexity and Pharmacological Zinc and Copper

Weaned pigs are typically fed complex, highly digestible diets to maximize feed intake and weight gain as they transition into the nursery. Further, pharmacological concentrations of zinc (Zn) and copper (Cu) are commonly fed to mitigate weaning-related diarrhea and performance reductions. A 2 x 2 factorial design was utilized to determine the effect of diet complexity with or without Zn and Cu. Four-hundred and thirty-two weaned pigs were randomly allotted to 48 pens (n = 9 pigs/pens). Pens were assigned to one of four diets: 1) A high soybean meal diet (Simple), 2) Simple + ZnCu, 3) Low soybean meal diet with spray-dried plasma, casein, and oats (Complex), and 4) Complex + ZnCu. Diets were fed in two 14 d phases. For ZnCu there were 3,000 and 2,000 ppm Zn in phase 1 and 2, and 200 ppm Cu in both phases. Bodyweight and feed intake were determined in phase 1 (d 0–14) and phase 2 (d 15–28). Pen was the experimental unit and all data were analyzed by diet complexity, pharmacological minerals and their interaction. No complexity by ZnCu interaction or diet complexity effects were observed in the 28 d study. However, ZnCu increased ADG (0.23 vs. 0.16 kg/day, P &lt; 0.0001), ADFI (0.28 vs. 0.24 kg/d, P &lt; 0.0001), and GF (0.80 vs. 0.69, P &lt; 0.0001) in phase 1. In phase 2, ZnCu increased ADG by 9% (P = 0.008) and ADFI by 16% (P = 0.0001) compared to non-supplemented counterparts. Overall (0–28 d), ZnCu pigs had heavier end bodyweight (15.9 vs. 14.5 kg, P = 0.009), and greater ADFI (0.47 vs. 0.41 kg/d, P &lt; 0.0001). In conclusion, diet complexity (high levels of soybean meal versus specialized protein alternatives) did not alter nursery performance. Irrespective of diet complexity, pharmacological Zn and Cu improved performance parameters.

Contribution of Early-Postmortem Proteome and Metabolome to Ultimate pH and Pork Quality

This study's objectives were to identify how subtle differences in ultimate pH relate to differences in pork quality and to understand how early-postmortem glycolysis contributes to variation in ultimate pH. The hypothesis was that elements in early-postmortem longissimus thoracis et lumborum proteome and metabolome could be used to predict quality defects associated with pH decline. Temperature and pH of the longissimus thoracis et lumborum were measured at 45 min, 24 h, and 14 d postmortem. Quality measurements were made after 14 d of aging. Groups were classified as normal pH (NpH; x̄ = 5 . 59 [5.53–5.67]; NpH, n = 10) and low pH (LpH; x̄ = 5 . 42 [5.38–5.45]; LpH, n = 10) at 14 d postmortem. Metabolites from 45 min postmortem were identified using GC-MS. Relative differences between proteins were quantified with two-dimensional difference in gel electrophoreses, and spots were identified with MALDI-MS. Western blot analyses were used to measure phosphofructokinase, peroxiredoxin-2, and reduced and non-reduced adenosine monophosphate deaminase-2 at 45 min and 14 d postmortem. Ultimate pH classification did not affect 45-min-postmortem pH (P = 0.64); 14-d pH was different between groups (P &lt; 0.01). NpH had less purge loss (P &lt; 0.01), was darker (P &lt; 0.01), had lower star probe (P &lt; 0.01), and had less intact day-7 desmin (P = 0.02). More pyruvate (P = 0.01) and less lactate (P = 0.09) was observed in NpH, along with more soluble lactate dehydrogenase (P = 0.03) and pyruvate kinase (P &lt; 0.10). These observations indicate that differences in enzyme abundance or solubility may produce more pyruvate and less lactate. Fructose 6-phosphate was more abundant (P = 0.08) in the LpH group, indicating that phosphofructokinase may be involved in glycolytic differences. Furthermore, greater abundance of heat shock proteins, peroxiredoxin-2 (P = 0.02), and malate (P = 0.01) early postmortem all suggest differences in mitochondrial function and oxidative stability that contribute to quality differences. These results show that even subtle changes in ultimate pH can influence pork quality. The proteome and metabolome at 45 min postmortem are associated with variation in the extent of pH decline.

Highly Fermentable Fiber Alters Fecal Microbiota and Mitigates Swine Dysentery Induced by Brachyspira hyodysenteriae

Simple Summary

Dietary manipulation to prevent disease is essential to reduce antimicrobial usage in the swine industry. This study aimed to evaluate whether replacing lowly fermentable fibers with highly fermentable fibers would mitigate disease during a 42 day Brachyspira hyodysenteriae challenge. Pigs fed the highly fermentable diet had improved growth performance compared with those fed diets of lower fermentability and had near absence of clinical swine dysentery. Further, several microbial genera were altered by dietary manipulation, bacteria that may be synergistic or antagonistic to Brachyspira hyodysenteriae. Taken together, this study demonstrates that replacing lowly fermentable fiber with highly fermentable fibers mitigates disease during Brachyspira hyodysenteriae challenge and may help reduce antimicrobial usage in treatment and control of this pathogen.

Abstract

Brachyspira hyodysenteriae is an etiological agent of swine dysentery (SD). Diet fermentability plays a role in development of SD, but the mechanism(s) of action are largely unknown. Thus, this study aimed to determine whether replacing lowly fermentable fiber with highly fermentable fiber would mitigate a 42 d B. hyodysenteriae challenge. Thirty-nine barrows were allocated to dietary treatment groups: (1) 20% corn distillers dried grain with solubles (DDGS), 0% beet pulp (BP) or resistant starch (RS; lowly fermentable fiber (LFF)); (2) 10% DDGS, 5% BP, 5% RS (medium fermentable fiber (MFF)); and (3) 0% DDGS, 10% BP, 10% RS (highly fermentable fiber (HFF)). On day post inoculation 0, pigs were inoculated with B. hyodysenteriae. Overall, 85% LFF pigs developed clinical SD, 46% of MFF pigs developed SD, and 15% of HFF pigs developed SD (p < 0.05). Overall average daily gain (ADG) differed among all treatments (p < 0.001), with LFF pigs having the lowest ADG. For HFF pigs, ADG was 37% greater than LFF pigs (p < 0.001) and 19% greater than MFF pigs (p = 0.037). The LFF diet had greater relative abundance of Shuttleworthia and Ruminococcus torques. Further, microbiota of pigs that developed SD had enriched Prevotellaceae. Collectively, replacing DDGS with highly fermentable fiber reduced clinical SD, improved performance, and modulated fecal microbiota during B. hyodysenteriae challenge.

Nutritional approaches to slow late finishing pig growth: implications on carcass composition and pork quality

Although pork producers typically aim to optimize growth rates, occasionally it is necessary to slow growth, such as when harvest facility capacity is limited. In finishing pigs, numerous dietary strategies can be used to slow growth so pigs are at optimal slaughter body weights when harvest facility capacity and/or access is restored. However, the impact of these diets on pork carcass quality is largely unknown. Thus, this study aimed to evaluate the efficacy of dietary strategies to slow growth in late finishing pigs and evaluate their effects on carcass composition and pork quality. Mixed-sex pigs (n = 897; 125 ± 2 kg BW) were randomly allotted across 48 pens and assigned to 1 of 6 dietary treatments (n = 8 pens/treatment): (1) Control diet representative of a typical finisher diet (CON); (2) diet containing 3% calcium chloride (CaCl2); (3) diet containing 97% corn and no soybean meal (Corn); (4) diet deficient in isoleucine (LowIle); (5) diet containing 15% neutral detergent fiber (NDF) from soybean hulls (15% NDF); and (6) diet containing 20% NDF from soybean hulls (20% NDF). Over 42 d, pen body weights and feed disappearance were collected. Pigs were harvested in 3 groups (14, 28, and 42 d on feed) and carcass data collected. From the harvest group, 1 loin was collected from 120 randomly selected carcasses (20 loins/treatment) to evaluate pork quality traits. Overall, ADG was reduced in CaCl2, Corn, and 20% NDF pigs compared with CON pigs (P < 0.001). However, ADFI was only reduced in CaCl2 and 20% NDF pigs compared with CON (P < 0.001). Feed efficiency was reduced in CaCl2 and Corn pigs compared with CON (P < 0.001). Hot carcass weights were reduced in CaCl2 pigs at all harvest dates (P < 0.001) and were reduced in Corn and 20% NDF pigs at days 28 and 42 compared with CON pigs (P < 0.001). In general, CaCl2 and 20% NDF diets resulted in leaner carcasses, whereas the Corn diet increased backfat by 42 d on test (P < 0.05). Loin pH was reduced and star probe increased in CaCl2 pigs compared with CON pigs (P < 0.05); no treatments differed from CON pigs regarding drip loss, cook loss, color, firmness, or marbling (P ≥ 0.117). Overall, these data indicate that several dietary strategies can slow finishing pig growth without evidence of behavioral vices. However, changes to carcass composition and quality were also observed, indicating quality should be taken into consideration when choosing diets to slow growth.

The Role of Salmonella Genomic Island 4 in Metal Tolerance of Salmonella enterica Serovar I 4,[5],12:i:- Pork Outbreak Isolate USDA15WA-1

Multidrug-resistant (MDR; resistance to >3 antimicrobial classes) Salmonella enterica serovar I 4,[5],12:i:- strains were linked to a 2015 foodborne outbreak from pork. Strain USDA15WA-1, associated with the outbreak, harbors an MDR module and the metal tolerance element Salmonella Genomic Island 4 (SGI-4). Characterization of SGI-4 revealed that conjugational transfer of SGI-4 resulted in the mobile genetic element (MGE) replicating as a plasmid or integrating into the chromosome. Tolerance to copper, arsenic, and antimony compounds was increased in Salmonella strains containing SGI-4 compared to strains lacking the MGE. Following Salmonella exposure to copper, RNA-seq transcriptional analysis demonstrated significant differential expression of diverse genes and pathways, including induction of at least 38 metal tolerance genes (copper, arsenic, silver, and mercury). Evaluation of swine administered elevated concentrations of zinc oxide (2000 mg/kg) and copper sulfate (200 mg/kg) as an antimicrobial feed additive (Zn+Cu) in their diet for four weeks prior to and three weeks post-inoculation with serovar I 4,[5],12:i:- indicated that Salmonella shedding levels declined at a slower rate in pigs receiving in-feed Zn+Cu compared to control pigs (no Zn+Cu). The presence of metal tolerance genes in MDR Salmonella serovar I 4,[5],12:i:- may provide benefits for environmental survival or swine colonization in metal-containing settings.

Brachyspira hyodysenteriae Infection Reduces Digestive Function but Not Intestinal Integrity in Growing Pigs While Disease Onset Can Be Mitigated by Reducing Insoluble Fiber

Swine dysentery (SD) induced by Brachyspira hyodysenteriae manifests as mucohemorrhagic diarrhea in pigs, but little is known about the changes that occur to the gastrointestinal tract during this disease. It is thought that dietary fibers alter disease pathogenesis, although the mechanisms of action are unclear. Thus, the objectives of this study were to characterize intestinal integrity, metabolism, and function in pigs during SD and determine if replacing insoluble fiber with fermentable fibers mitigates disease. Thirty-six B. hyodysenteriae-negative gilts [24.3 ± 3.6 kg body weight (BW)] were assigned to one of three treatment groups: (1) B. hyodysenteriae negative, control diet (NC); (2) B. hyodysenteriae challenged, control diet (PC); and (3) B. hyodysenteriae challenged, highly fermentable fiber diet (RS). The NC and PC pigs were fed the same control diet, containing 20% corn distillers dried grains with solubles (DDGS). The RS pigs were fed a diet formulated with 5% sugar beet pulp and 5% resistant potato starch. On days post inoculation (dpi) 0 and 1, pigs were inoculated with B. hyodysenteriae or sham. Pigs were euthanized for sample collection after onset of SD. The challenge had high morbidity, with 100% of PC and 75% of RS pigs developing clinical SD. The timing of onset of clinical SD differed due to treatment, with RS pigs having a delayed onset (dpi 9) of clinical SD compared with dpi 7 for PC pigs. Colon transepithelial resistance was increased and macromolecule permeability was reduced in PC pigs compared with NC pigs (P < 0.01). Minimal changes in ileal permeability, mitochondrial function, or volatile fatty acids (VFAs) were observed. Total VFA concentrations were lower in the colon and cecum in both PC and RS pigs compared to NC pigs (both P < 0.05), but iso-acids were higher (both P < 0.05). Total tract digestibility of dry matter (DM), organic matter (OM), nitrogen (N), and gross energy (GE) was lower in PC pigs compared with both NC and RS pigs (both P < 0.001). These data indicate that SD reduces digestive function but does not reduce ex vivo intestinal integrity. Further, replacement of insoluble fiber with highly fermentable fibers mitigated and delayed the onset of SD.

Epithelial-mesenchymal transition of absorptive enterocytes and depletion of Peyer's patch M cells after PEDV infection

This study focused on intestinal restitution including phenotype switching of absorptive enterocytes and the abundance of different enterocyte subtypes in weaned pigs after porcine epidemic diarrhea virus (PEDV) infection. At 10 days post-PEDV-inoculation, the ratio of villus height to crypt depth in both jejunum and ileum had restored, and the PEDV antigen was not detectable. However, enterocytes at the villus tips revealed epithelial-mesenchymal transition (EMT) in the jejunum in which E-cadherin expression decreased while expression of N-cadherin, vimentin, and Snail increased. Additionally, there was reduced expression of actin in microvilli and Zonula occludens-1 (ZO-1) in tight junctions. Moreover, the protein concentration of transforming growth factor β1 (TGFβ1), which mediates EMT and cytoskeleton alteration, was increased. We also found a decreased number of Peyer's patch M cells in the ileum. These results reveal incomplete restitution of enterocytes in the jejunum and potentially impaired immune surveillance in the ileum after PEDV infection.

The effect of lactose and a prototype Lactobacillus acidophilus fermentation product on digestibility, nitrogen balance, and intestinal function of weaned pigs

The objective of this study was to determine the effects of lactose (LA) and a prototype Lactobacillus acidophilus fermentation product (FP) on growth performance, diet digestibility, nitrogen (N) balance, and intestinal function of weaned pigs. Twenty-eight newly weaned pigs [approximately 21 d of age; initial body weight (BW) = 5.20 ± 0.15 kg] were housed in metabolism crates and assigned to one of four treatments (n = seven pigs per treatment) corresponding to a 2 × 2 factorial design: with (LA+; 15% inclusion) or without (LA-) LA and with (FP+) or without (FP-) the prototype FP (1 g of FP per kilogram of diet; Diamond V, Cedar Rapids, IA). Feed and water were provided ad libitum. At day 5, pigs were orally given lactulose and mannitol to assess small intestinal permeability. Fecal samples were collected on days 5-9 to determine the apparent total tract digestibility (ATTD) of dry matter (DM), gross energy (GE), and N. Total urine output and fecal samples were collected on days 10-13 to determine N retention. On day 15, all pigs were euthanized to collect intestinal lumen and tissue samples. Data were analyzed for the main effects of LA and FP and their interaction using the MIXED procedure of SAS. Lactose improved average daily feed intake (ADFI; P = 0.017), the ATTD of DM (P = 0.014), the ATTD of GE (P = 0.028), and N retention (P = 0.043) and tended to increase the butyric acid concentration in the colon (P = 0.062). The FP tended to increase the digestibility of N (P = 0.090). Neither LA nor the FP affected intestinal barrier function or inflammation markers. The interaction between LA and FP affected intestinal morphology: in the jejunum, pigs fed LA+FP- had increased villus height compared with those fed LA+FP+ and LA-FP-, whereas LA+FP+ was intermediate (interaction P = 0.034). At the terminal ileum, pigs fed LA-FP+ and LA+FP- had increased villus height and villus: crypt compared with those fed LA-FP-, whereas LA+FP+ was intermediate (interaction P = 0.007 and P = 0.007, respectively). In conclusion, the addition of LA brings important nutritional attributes to nursery diets by improving feed intake, digestibility of DM and GE, and the N retention of weaned pigs; however, the functional capacity of LA to improve markers of intestinal function is limited. On the other hand, the FP showed only a mild increase in the digestibility of N but a limited capacity to improve markers of intestinal function.

Intraepithelial T Cells Diverge by Intestinal Location as Pigs Age

T cells resident within the intestinal epithelium play a central role in barrier integrity and provide a first line of immune defense. Intraepithelial T cells (IETs) are among the earliest immune cells to populate and protect intestinal tissues, thereby giving them an important role in shaping gut health early in life. In pigs, IETs are poorly defined, and their maturation in young pigs has not been well-studied. Given the importance of IETs in contributing to early life and long-term intestinal health through interactions with epithelial cells, the microbiota, and additional environmental factors, a deeper characterization of IETs in pigs is warranted. The objective of this study was to analyze age- and intestinal location-dependent changes in IETs across multiple sites of the small and large intestine in pigs between 4- and 8-weeks of age. IETs increased in abundance over time and belonged to both γδ and αβ T cell lineages. Similar compositions of IETs were identified across intestinal sites in 4-week-old pigs, but compositions diverged between intestinal sites as pigs aged. CD2⁺CD8α⁺ γδ T cells and CD4^-CD8α⁺ αβ T cells comprised >78% of total IETs at all intestinal locations and ages examined. Greater percentages of γδ IETs were present in large intestine compared to small intestine in older pigs. Small intestinal tissues had greater percentages of CD2⁺CD8α^- γδ IETs, while CD2⁺CD8α⁺ γδ IET percentages were greater in the large intestine. Percentages of CD4^-CD8α⁺ αβ IETs increased over time across all intestinal sites. Moreover, percentages of CD27⁺ cells decreased in ileum and large intestine over time, indicating increased IET activation as pigs aged. Percentages of CD27⁺ cells were also higher in small intestine compared to large intestine at later timepoints. Results herein emphasize 4- to 8-weeks of age as a critical window of IET maturation and suggest strong associations between intestinal location and age with IET heterogeneity in pigs.

Dietary Soluble and Insoluble Fiber With or Without Enzymes Altered the Intestinal Microbiota in Weaned Pigs Challenged With Enterotoxigenic E. coli F18

Post-weaning diarrhea caused by enterotoxigenic E. coli (ETEC) causes significant economic losses for pig producers. This study was to test the hypotheses that an ETEC challenge disrupts intestinal microbial homeostasis and the inclusion of dietary soluble (10% sugar beet pulp) or insoluble fiber (15% corn distillers dried grains with solubles) with or without exogenous carbohydrases will protect or restore the gut microbial homeostasis in weaned pigs. Sixty crossbred piglets (6.9 ± 0.1 kg) were blocked by body weight and randomly assigned to one of six treatments (n = 10), including a non-challenged control (NC), ETEC F18-challenged positive control (PC), ETEC-challenged soluble fiber without (SF-) or with carbohydrases (SF+), and ETEC-challenged insoluble fiber without (IF-) or with carbohydrases (IF+). Pigs were housed individually and orally received either ETEC inoculum or PBS-sham inoculum on day 7 post-weaning. Intestinal contents were collected on day 14 or 15. The V4 region of the bacterial 16S rRNA was amplified and sequenced. High-quality reads (total 6,671,739) were selected and clustered into 3,330 OTUs. No differences were observed in α-diversity among treatments. The ileal microbiota in NC and PC had modest separation in the weighted PCoA plot; the microbial structures were slightly altered by SF+ and IF- compared with PC. The PC increased ileal Escherichia-Shigella (P < 0.01) and numerically decreased Lactobacillus compared to NC. Predicted functional pathways enriched in the ileal microbiota of PC pigs indicated enhanced activity of Gram-negative bacteria, in agreement with increased Escherichia-Shigella. The SF+ tended to decrease (P < 0.10) ileal Escherichia-Shigella compared to PC. Greater abundance of ileal Streptococcus, Turicibacter, and Roseburia and colonic Prevotella were observed in SF- and SF+ than PC (P < 0.05). Pigs fed IF + had greater Lactobacillus and Roseburia than PC pigs (P < 0.05). The ETEC challenge reduced total volatile fatty acid (VFA) compared with NC (P < 0.05). The SF+ tended to increase (P < 0.10) and SF- significantly increased (P < 0.05) colonic total VFA compared with PC. Collectively, ETEC challenge disrupted gut microbial homeostasis and impaired microbial fermentation capacity. Soluble fiber improved VFA production. Dietary fiber and carbohydrases altered microbiota composition to maintain or restore microbial homeostasis.

Intraepithelial T cell phenotype and function diverge by intestinal location with age

Intestinal intraepithelial T cells (IETs) provide a first line of defense against intestinal pathogens and play an important role in immune tolerance versus activation. In pigs, intestinal T cell populations stabilize at ~8 weeks of age, but IET phenotypes and function are poorly understood during the early postnatal period. Better understanding age- and location-dependent characteristics of porcine IETs may be useful in developing strategies to maintain intestinal integrity and improve health. To assess impacts of age and intestinal location on abundance and composition of IETs, sections of jejunum, ileum, cecum, and colon from 4-, 6-, and 8-week-old pigs were analyzed by histologic staining and flow cytometric analyses. IET abundance increased with age, and CD2+CD8α+γδ and CD4−CD8α+αβ T cells were the primary IET populationsin all samples (&gt;78%). Compositions of IETs were similar at all locations in 4-week-old pigs. As pigs aged, cecal and colonic IET compositions remained similar to each other but diverged from small intestinal IETs, while jejunal and ileal IET compositions diverged from both large intestinal IETs and each other. These findings indicate both intestinal location and age are drivers of IET heterogeneity. Small intestinal IETs had lower percentages of γδ IETs in 6- and 8-week-old pigs, and CD4−CD8α+αβ IETs increased in abundance at all intestinal locations as pigs aged. Percentages of CD27+IETs in ileum and large intestine decreased over time, but decreases were more drastic in large intestine, suggesting IETs in the distal but not proximal intestinal tract were activated as pigs aged. Small intestinal IET compositions closely resembled human IET populations, highlighting pigs as a biomedical model for IET research.

Increasing the ratio of SID lysine to metabolizable energy improves pig performance during a viral challenge

Porcine reproductive and respiratory syndrome virus (PRRSV) compromises pig performance. However, increasing standardized ileal digestible Lys per Mcal metabolizable energy (SID Lys:ME) above requirement has been shown to mitigate reduced performance seen during a porcine reproductive and respiratory syndrome (PRRS) virus challenge. The objective of this study was to evaluate the effects of increasing the dietary SID Lys:ME from 100% National Research Council (NRC) requirement to 120% of the requirement in vaccinated (vac+; modified live vaccine Ingelvac PRRS) and non-vaccinated (vac-; no PRRS vaccine) grower pigs subjected to a PRRSV challenge. In addition, the dietary formulation approach to achieve the 120% ratio by increasing Lys relative to energy (HL) or diluting energy in relation to Lys (LE) was evaluated. This allowed us to test the hypothesis that pigs undergoing a health challenge would have the ability to eat to their energy needs. Within vaccine status, 195 mixed-sex pigs, vac+ (35.2 ± 0.60 kg body weight [BW]) and vac- (35.2 ± 0.65 kg BW) were randomly allotted to one of three dietary treatments (2.67, 3.23, or 3.22 g SID Lys:ME) for a 42-d PRRS virus challenge study representing 100%, 120%, and 120% of NRC requirement, respectively. Pigs were randomly allotted across two barns, each containing 24 pens with 7 to 10 pigs per pen (8 pens per diet per vaccine status). On day post-inoculation 0, both barns were inoculated with PRRSV and started on experimental diets. Within vaccine status, weekly and overall challenge period pig performance were assessed. In both vac+ (P < 0.05) and vac- (P < 0.05) pigs, the HL and LE diets increased end BW and overall average daily gain (ADG) ADG compared with pigs fed the control diet (P < 0.05). Overall, average daily feed intake (ADFI) during the challenge period was greater (P < 0.05) for pigs fed the LE diet compared with pigs fed control and HL treatments, regardless of vaccine status (20% and 17% higher ADFI than the control in vac+ and vac- pigs, respectively). The HL vac+ pigs had the greatest gain to feed (G:F) compared with the control and LE pigs (0.438 vs. 0.394 and 0.391 kg/kg, respectively; P < 0.01). Feed efficiency was not impacted (P > 0.10) by treatment in the vac- pigs. In summary, PRRSV-challenged grower pigs consumed feed to meet their energy needs as indicated by the increase in ADFI when energy was diluted in the (LE) diet, compared with control pigs. In both PRRS vac+ and vac- pigs subsequently challenged with PRRSV, regardless of formulation approach, fed 120% SID Lys:ME diets resulted in enhanced overall growth performance.

Effect of a dual enteric and respiratory pathogen challenge on swine growth, efficiency, carcass composition, and pork quality1

The objective of this study was to determine the influence of a dual respiratory and enteric pathogen challenge on growth performance, carcass composition, and pork quality of high and low feed efficient pigs. Pigs divergently selected for low and high residual feed intake (RFI, ~68 kg) from the 11th generation of Iowa State University RFI project were used to represent high and low feed efficiency. To elicit a dual pathogen challenge, half of the pigs (n = 12/line) were inoculated with Mycoplasma hyopneumoniae (Mh) and Lawsonia intracellularis (MhLI) on days post-inoculation (dpi) 0. Pigs in a separate room of the barn were not inoculated and used as controls (n = 12/RFI line). Pigs were weighed and feed intake was recorded to calculate ADG, ADFI, and G:F for the acclimation period (period 1: dpi -21 to 0), during peak infection (period 2: dpi 0 to 42), and during the remaining growth period to reach market weight (period 3: dpi 42 to harvest). At ~125 kg, pigs were harvested using standard commercial procedures. Carcasses were evaluated for composition (weight, fat free lean, loin eye area, 10th rib fat depth) and meat quality (pH decline, temperature decline, Hunter L, a, and b, subjective color and marbling, star probe, drip loss, cook loss, proximate composition, and desmin degradation). Challenged pigs had lesser ADFI than controls during period 2 (P < 0.05), but had greater ADG and G:F during period 3 (P < 0.05). Selection for feed efficiency did not result in a differential response to MhLI (P > 0.05). Loin chops from the less feed efficient, high RFI pigs, had greater drip loss, greater cook loss, lesser moisture content, greater Hunter L values, and greater Hunter b values (P < 0.05) than loin chops from low RFI pigs. Infection status did not significantly affect carcass composition or pork quality traits (P > 0.05). These results indicate that a MhLI challenge early in growth did not significantly affect ultimate carcass composition or meat quality traits. Selection for greater feed efficiency in pigs did not affect their response to pathogenic challenge.

Impact of viral disease hypophagia on pig jejunal function and integrity

Pathogen challenges are often accompanied by reductions in feed intake, making it difficult to differentiate impacts of reduced feed intake from impacts of pathogen on various response parameters. Therefore, the objective of this study was to determine the impact of Porcine Reproductive and Respiratory Syndrome virus (PRRSV) and feed intake on parameters of jejunal function and integrity in growing pigs. Twenty-four pigs (11.34 ± 1.54 kg BW) were randomly selected and allotted to 1 of 3 treatments (n = 8 pigs/treatment): 1) PRRSV naïve, ad libitum fed (Ad), 2) PRRSV-inoculated, ad libitum fed (PRRS+), and 3) PRRSV naïve, pair-fed to the PRRS+ pigs' daily feed intake (PF). At 17 days post inoculation, all pigs were euthanized and the jejunum was collected for analysis. At days post inoculation 17, PRRS+ and PF pigs had decreased (P < 0.05) transepithelial resistance compared with Ad pigs; whereas fluorescein isothiocyanate-dextran 4 kDa permeability was not different among treatments. Active glucose transport was increased (P < 0.05) in PRRS+ and PF pigs compared with Ad pigs. Brush border carbohydrase activity was reduced in PRRS+ pigs compared with PF pigs for lactase (55%; P = 0.015), sucrase (37%; P = 0.002), and maltase (30%; P = 0.015). For all three carbohydrases, Ad pigs had activities intermediate that of PRRS+ and PF pigs. The mRNA abundance of the tight junction proteins claudin 2, claudin 3, claudin 4, occludin, and zonula occludens-1 were reduced in PRRS+ pigs compared with Ad pigs; however, neither the total protein abundance nor the cellular compartmentalization of these tight junction proteins differed among treatments. Taken together, this study demonstrates that the changes that occur to intestinal epithelium structure, function, and integrity during a systemic PRRSV challenge can be partially explained by reductions in feed intake. Further, long term adaptation to PRRSV challenge and caloric restriction does reduce intestinal transepithelial resistance but does not appear to reduce the integrity of tight junction protein complexes.

The impact of dietary supplementation of arginine during gestation in a commercial swine herd: I. Gilt reproductive performance

Supplemental arginine (Arg) during gestation purportedly benefits fetal development. However, the benefits of a gestational Arg dietary strategy in commercial production are unclear. Therefore, the objectives of this study examined Arg supplementation during different gestational stages and the effects on gilt reproductive performance. Pubertal gilts (n = 548) were allocated into 4 treatment groups: Control (n = 143; 0% supplemental Arg) or 1 of 3 supplemental Arg (1% as fed) treatments: from 15 to 45 d of gestation (n = 138; Early-Arg); from 15 d of gestation until farrowing (n = 139; Full-Arg); or from 85 d of gestation until farrowing (n = 128; Late-Arg). At farrowing, the number of total born (TB), born alive (BA), stillborn piglets (SB), mummified fetuses (MM), and individual piglet birth weights (BiWt) were recorded. The wean-to-estrus interval (WEI) and subsequent sow reproductive performance (to third parity) were also monitored. No significant effect of supplemental Arg during any part of P0 gestation was observed for TB, BA, SB, or MM (P ≥ 0.29). Offspring BiWt and variation among individual piglet birth weights did not differ (P = 0.42 and 0.89, respectively) among treatment groups. Following weaning, the WEI was similar among treatments (average of 8.0 ± 0.8 d; P = 0.88). Litter performance over 3 parities revealed a decrease (P = 0.02) in BA for Early-Arg fed gilts compared with all other treatments, whereas TB and WEI were similar among treatments over 3 parities (P > 0.05). There was an increased proportion of sows with average size litters (12 to 16 TB) from the Full-Arg treatment sows (76.8% ± 3.7%) when compared with Control (58.7% ± 4.2%; P = 0.01); however, the proportion of sows with high (>16 TB) and low (<12 TB) litters was not different among treatments (P = 0.20). These results suggest that gestational Arg supplementation had a minimal impact on reproductive performance in first parity sows. These data underscore the complexity of AA supplementation and the need for continued research into understanding how and when utilizing a gestational dietary Arg strategy can optimize fetal development and sow performance.

Acute systemic inflammatory response to lipopolysaccharide stimulation in pigs divergently selected for residual feed intake

Background

It is unclear whether improving feed efficiency by selection for low residual feed intake (RFI) compromises pigs’ immunocompetence. Here, we aimed at investigating whether pig lines divergently selected for RFI had different inflammatory responses to lipopolysaccharide (LPS) exposure, regarding to clinical presentations and transcriptomic changes in peripheral blood cells.

Results

LPS injection induced acute systemic inflammation in both the low-RFI and high-RFI line (n = 8 per line). At 4 h post injection (hpi), the low-RFI line had a significantly lower (p = 0.0075) mean rectal temperature compared to the high-RFI line. However, no significant differences in complete blood count or levels of several plasma cytokines were detected between the two lines. Profiling blood transcriptomes at 0, 2, 6, and 24 hpi by RNA-sequencing revealed that LPS induced dramatic transcriptional changes, with 6296 genes differentially expressed at at least one time point post injection relative to baseline in at least one line (n = 4 per line) (|log₂(fold change)| ≥ log₂(1.2); q < 0.05). Furthermore, applying the same cutoffs, we detected 334 genes differentially expressed between the two lines at at least one time point, including 33 genes differentially expressed between the two lines at baseline. But no significant line-by-time interaction effects were detected. Genes involved in protein translation, defense response, immune response, and signaling were enriched in different co-expression clusters of genes responsive to LPS stimulation. The two lines were largely similar in their peripheral blood transcriptomic responses to LPS stimulation at the pathway level, although the low-RFI line had a slightly lower level of inflammatory response than the high-RFI line from 2 to 6 hpi and a slightly higher level of inflammatory response than the high-RFI line at 24 hpi.

Conclusions

The pig lines divergently selected for RFI had a largely similar response to LPS stimulation. However, the low-RFI line had a relatively lower-level, but longer-lasting, inflammatory response compared to the high-RFI line. Our results suggest selection for feed efficient pigs does not significantly compromise a pig’s acute systemic inflammatory response to LPS, although slight differences in intensity and duration may occur.

Impact of porcine reproductive and respiratory syndrome virus on muscle metabolism of growing pigs1

Porcine reproductive and respiratory syndrome (PRRS) virus is one of the most economically significant pig pathogens worldwide. However, the metabolic explanation for reductions in tissue accretion observed in growing pigs remains poorly defined. Additionally, PRRS virus challenge is often accompanied by reduced feed intake, making it difficult to discern which effects are virus vs. feed intake driven. To account for this, a pair-fed model was employed to examine the effects of PRRS challenge and nutrient restriction on skeletal muscle and liver metabolism. Forty-eight pigs were randomly selected (13.1 ± 1.97 kg BW) and allotted to 1 of 3 treatments (n = 16 pigs/treatment): 1) PRRS naïve, ad libitum fed (Ad), 2) PRRS-inoculated, ad libitum fed (PRRS+), and 3) PRRS naïve, pair-fed to the PRRS-inoculated pigs' daily feed intake (PF). At days postinoculation (dpi) 10 and 17, 8 pigs per treatment were euthanized and tissues collected. Tissues were assayed for markers of proteolysis (LM only), protein synthesis (LM only), oxidative stress (LM only), gluconeogenesis (liver), and glycogen concentrations (LM and liver). Growth performance, feed intake, and feed efficiency were all reduced in both PRRS+ and PF pigs compared with Ad pigs (P < 0.001). Furthermore, growth performance and feed efficiency were additionally reduced in PRRS+ pigs compared with PF pigs (P < 0.05). Activity of most markers of LM proteolysis (μ-calpain, 20S proteasome, and caspase 3/7) was not increased (P > 0.10) in PRRS+ pigs compared with Ad pigs, although activity of m-calpain was increased in PRRS+ pigs compared with Ad pigs (P = 0.025) at dpi 17. Muscle reactive oxygen species production was not increased (P > 0.10) in PRRS+ pigs compared with Ad pigs. However, phosphorylation of protein synthesis markers was decreased in PRRS+ pigs compared with both Ad (P < 0.05) and PF (P < 0.05) pigs. Liver gluconeogenesis was not increased as a result of PRRS; however, liver glycogen was decreased (P < 0.01) in PRRS+ pigs compared with Ad and PF pigs at both time points. Taken together, this work demonstrates the differential impact a viral challenge and nutrient restriction have on metabolism of growing pigs. Although markers of skeletal muscle proteolysis showed limited evidence of increase, markers of skeletal muscle synthesis were reduced during PRRS viral challenge. Furthermore, liver glycogenolysis seems to provide PRRS+ pigs with glucose needed to fuel the immune response during viral challenge.

111 Common nutritional and infectious health challenges in nursery pigs

Poor starting nursery pigs are a common source of frustration for pork producers due to suboptimal lean tissue production and failure to thrive. This is generally a multifactorial issue with potential nutritional, infectious and management contributors. Commonly encountered respiratory and enteric pathogens include porcine reproductive and respiratory syndrome virus (PRRSV), influenza A virus (IAV), porcine enteric coronaviruses (TGEV/PEDV/PDCV), and group A, B, and C rotaviruses, as well as Salmonella typhimurium, enterotoxigenic Escherichia coli, Streptococcus suis, and Haemophilus parasuis. Infection with one or more of these agents can ultimately antagonize pig health and performance. However, while these specific pathogens may be causing an observed disease symptom, pigs may have been predisposed to infection due to various management, nutritional, and environmental risk factors. As many of these potential pathogens are endemic in production systems, it is important to remember that simply detecting a potential pathogen within a population is often not sufficient to assign cause for poor growth and production. To help fully interpret the impact of a detected agent, diagnostic efforts should focus on providing proof that the agent is actually causing disease. Molecular detection methods, such as PCR, are increasingly available for common pathogens and have high diagnostic sensitivity but lower diagnostic specificity. This paper will discuss the clinical signs and gross and microscopic lesions associated with common nursery pig pathogens, as well as proper sampling and diagnostic testing necessary to detect and confirm disease following infection with these agents.

PSVI-15 Effects of Vitamin B12, Sodium Salicylate, and electrolyte supplementation on alleviating Porcine Reproductive and Respiratory Syndrome symptoms in nursery pigs

Vitamin B12, sodium salicylate, and electrolyte treatments are commonly used to modulate pathogen induced fevers and aid in appetite stimulation. Therefore, the objective of this study was to determine the extent to which a B12 and sodium salicylate or an isotonic electrolyte treatment could improve growth performance and feed intake, and reduce the febrile response in porcine reproductive and respiratory syndrome (PRRS) virus inoculated pigs. A total of 32 PRRS-naïve gilts (7.7 ±1.5 kg BW; PIC Camborough x PIC 337) were selected and randomly assigned to individual pens across four treatments (n = 8/trt): 1) Control, PRRS-naïve, 2) PRRS virus infected, 3) As #2 plus B12 and sodium salicylate supplementation, and 4) As #2 plus isotonic electrolyte supplementation. On days post inoculation (dpi) 0, pigs were inoculated with PRRS virus. B12 was administered weekly, sodium salicylate and the electrolyte solution were given orally daily in the water or fed daily from dpi 4-18. Body temperatures and feed intakes were measured daily, and body weights, G:F, and PRRS serology assessed weekly for 21 dpi. Over the 21 day test period, irrespective of treatment, PRRS virus infection resulted in a significant increase in PRRS viremia and antibody titers compared to the control (P < 0.05). Compared to treatment #2, B12 + sodium salicylate and electrolyte treatments did not have differing body temperatures, ADG, ADFI or G:F. However, PRRS infection resulted in a significant increase in average body temperature compared to the control (39.8 vs. 39.3 oC, respectively, P = 0.021). Compared to the control, PRRS infection reduced overall ADG by 83% (0.54 verses 0.09 g/d, P < 0.001), end BW by 9 kg (P < 0.001) and ADFI by 11% (P < 0.001) compared to the control. Although treatment did not improve pig performance in the face of PRRS, mortality rates were significantly (P < 0.050) reduced compared to the PRRS only treatment.