Interactions between corticotropin releasing factor signaling and prophylactic antibiotics on measures of intestinal function in weaned and transported pigs

The study objective was to evaluate the interaction between corticotrophin releasing factor (CRF) receptor signaling and prophylactic antibiotic administration on intestinal physiology in newly weaned and transported pigs. Pigs (n = 56; 5.70 ± 1.05 kg) were weaned (20.49 ± 0.64 d), a blood sample was taken, and then pigs were given an intraperitoneal injection of saline (SAL; n = 28 pigs) or a CRF receptor antagonist (CRFA; n = 28 pigs; 30 μg/kg body weight; Astressin B), and then were transported in a livestock trailer for 12 h and 49 min. A second and third intraperitoneal injection was given at 4 h 42 min and 11 h 36 min into the transport process, respectively. Following transport, 4 SAL and 4 CRFA pigs were blood sampled and euthanized. The remaining 48 pigs were individually housed and given dietary antibiotics [AB; n = 12 SAL and 12 CRFA pigs; chlortetracycline (441 ppm) + tiamulin (38.6 ppm)] or no dietary antibiotics (NAB; n = 12 SAL and 12 CRFA pigs) for 14 d post-transport. Blood was collected at 12 h and on d 3, 7, and 14, and then pigs were euthanized on d 7 (n = 24) and d 14 (n = 24) post-weaning and transport. Circulating cortisol was reduced (p = 0.05) in CRFA pigs when compared to SAL pigs post-weaning and transport. On d 7, jejunal villus height and crypt depth was greater overall (p < 0.05) in AB-fed pigs versus NAB-fed pigs. On d 14, ileal crypt depth was reduced (p = 0.02) in CRFA pigs when compared to SAL pigs. Jejunal CRF mRNA abundance tended to be reduced (p = 0.09) on d 7 in CRFA pigs versus SAL pigs. On d 14, jejunal tumor necrosis factor-alpha was reduced (p = 0.01) in AB-fed pigs versus NAB-fed pigs. On d 7, change in glucose short-circuit current tended to be increased (p = 0.07) in CRFA pigs fed the AB diet when compared to CRFA pigs fed the NAB diet. In conclusion, CRFA pigs and pigs fed AB had some similar biological intestinal function measures post-weaning and transport.

Scratch that itch: Farrowing crate scratching enrichment for sows

Developing effective enrichments is important for improving pig (Sus scrofa) welfare as it increases species-specific behaviours, decreases abnormal behaviours, and increases time active. However, few enrichments are available for sows in farrowing crates. Pigs are often observed to scratch, or rub against objects, however enrichments designed to provide a scratching outlet have never been tested in sows. We examined the behaviour and welfare of sows in farrowing crates when they were presented with one of two types of scratchpad enrichment. Sows (n = 18) of parities two (P2) and three (P3) were housed for 25 days and assigned no enrichment (Control) or a scratch-pad made of plastic mats (Plastic) or coir fibre mats (Fibre). Parity two Plastic sows scratched for a longer total duration than P2 and P3 Fibre sows, P3 Plastic sows, and P2 Control sows. Parity two Plastic sows also displayed scratching bouts more frequently than all except P3 Control sows. There were no body lesion differences between treatments. Abnormal behaviour and proportion of time spent in different postures also did not differ between treatments. Plastic scratch-pads may be a suitable enrichment for farrowing crates as they increased the natural behaviour of scratching. More research is needed to refine the scratch-pad design and measure motivation before it can be concluded that scratch-pads are a successful enrichment that should be implemented on-farm.

The effect of dietary vitamin D supplementation on sodium-dependent phosphate uptake and expression of NaPi-IIb in the small intestine of weanling pigs

Two experiments were conducted to investigate the effects of 1,25(OH)2D3 to stimulate Na+-dependent phosphate uptake in Caco-2 cells, and the effects of dietary vitamin D supplementation to vitamin D-deficient nursery pigs on Na+-dependent nutrient uptake and mRNA expression of NaPi-IIb cotransporter and calbindin D9k in the jejunum. In Exp. 1, 250,000 Caco-2 cells were seeded on Costar 12 mm Snapwell inserts with a 0.40 µm polycarbonate filter and a seeding density of 0.25 × 106 and studied at 15 d postconfluence. Cells were treated with 10 nM of either 1,25(OH)2D3 or vehicle for 48 h and then mounted in modified Ussing chambers for transepithelial measurements. In Exp. 2, pigs (n = 32) were removed from sows at 3 d of age, placed on a vitamin D-deficient milk replacer diet and housed in a room devoid of sunlight and UV light in the range of 280 to 300 nm. On day 28, serum 25(OH)D3 concentrations were measured to verify low vitamin D status. Pigs (BW 10.10 ± 0.38 kg) were then individually housed day 28 postweaning and allotted to 1 of 2 dietary treatments. Dietary treatments consisted of corn-soybean-based diets with vitamin D supplementations of 0 or 1,500 IU/kg diet for 12 d. Blood samples were taken from the brachiocephalic vein on the initial (day 0) and final day (day 10, 11, or 12) of the study for analysis of serum 25(OH)D3, P, and Ca. Pigs were euthanized and jejunal segments were harvested and used in modified Ussing chambers and for RNA isolation and subsequent quantitative RT-PCR analysis. In Exp. 1, treating Caco-2 cells with 10 nM 1,25(OH)2D3 resulted in a 52% increase (P < 0.005) in Na+-dependent phosphate uptake compared with cells treated with a vehicle. In Exp. 2, Na+-dependent phosphate and glucose transport did not differ (P > 0.10) among treatment groups. Additionally, NaPi-IIb and calbindin D9k mRNA expression were not different (P > 0.10) between treatment groups. No differences (P > 0.10) were detected in final serum P or 25(OH)D3 concentrations between treatments. However, serum Ca linearly increased (P < 0.05) as the concentration of supplemental vitamin D increased in the diet. Overall, while 1,25(OH)2D3 stimulated Na+-dependent phosphate uptake in Caco-2 cells, supplementing diets with 1,500 IU/kg vitamin D3 from cholecalciferol did not increase jejunal Na+-dependent phosphate uptake or NaPi-IIb mRNA expression over that of pigs fed diets with no supplemental cholecalciferol.

PSIII-13 Effects of Saccharomyces Cerevisiae Fermentation Products on Lactating Sow Performance

Lactating sows (N=140, York x Landrace) were used to evaluate the effects of a liquid prototype (LIQP) and dry (XPC®; Diamond V) Saccharomyces cerevisiae feed additives on sow and litter performance. Sows were fed a common gestation diet (0.55% SID-Lysine) until d112 of pregnancy and then allotted to lactation treatments: 1) Control diet (CON; 1.00% SID-Lysine), 2) CON +15 mL of LIQP from d112 to weaning (LIQ), 3) CON +0.20% of XPC from d112 to weaning (DRY), and 4) DRY +15 mL of LIQP from d112 to d7 post-farrowing (D+L). The LIQP was given once daily using an oral dose gun and XPC was included in the feed. Immunoglobulin concentrations were estimated on colostrum samples using Brix refractometer and piglet d 1 serum immunocrit ratio and plasma IgA and IgG. Daily sow water intake and daily feed intake (DFI) from d112 of gestation to d7 post-farrowing and weekly feed intake (ADFI) were recorded. There were no treatment effects on sow BW, backfat, or loin depth (P &gt;0.05) although sows from LIQ group had numerically smaller BW reductions compared to CON sows (4.9% vs 7.2%, P=0.19). LIQ sows had greater DFI and CON lower DFI during week 1 of lactation (P=0.04) as well as ADFI for weeks 2, 3, and overall lactation period (P&lt; 0.01) with DRY and D+L sows being intermediate. Water intake, immunoglobulins, and litter performance did not differ among treatments (P &gt;0.05) although pigs from LIQ sows, compared to CON, had numerically increased weaning (6.14 vs 5.82kg, P &gt;0.05) and litter weights (63.2 vs 60.1kg, P &gt;0.05). LIQ sows had 0.7 d reduced wean-to-estrus interval (P&lt; 0.001) and tended to have greater conception rates (P=0.07). In conclusion, LIQ supplementation of lactating sows improves feed intake, allowing sows to keep body reserves, and have better subsequent rebreeding performance.

241 Evaluation of a DFM and OA, Alone or in Combination, on Sow Reproductive and Litter Growth Performance

Forty-seven sows and their progeny were used to determine if feeding gestating and lactating sows a Bacillus licheniformis direct-fed microbial (DFM), an organic acid blend of medium chain and short chain fatty acids (OA), or in combination improves sow lactation feed and water intake, litter growth, and subsequent reproductive performance. On approximately d80 of gestation, sows were fed one of four diets in a 2 x 2 factorial design: 1) gestation control (CON; 0.55% SID Lysine), 2) CON with DFM (1.6x109 CFU/kg of complete feed), 3) CON with 0.4% OA, 4) CON with both DFM and OA. Dietary treatments were also fed throughout lactation (1.00% SID Lysine) starting on approximately d112 of gestation when sows entered farrowing facility. There was a tendency (P = 0.079) for DFM to decrease the amount of sow body weight loss in lactation by approximately 6% compared to sows not consuming the DFM, likely related to DFM sows numerically (P = 0.124) consuming 8.4% more feed during d7-14 of lactation. Sows fed the OA diets had fewer mummies/litter (P = 0.038) compared to diets not containing OA. Sows fed diets with the DFM gave birth to lighter pigs born alive (P = 0.003) compared to non-DFM fed sows, and a tendency for an interaction (P = 0.092) existed where feeding OA+DFM lessened the decrease in born alive BW. There was an interaction tendency (P = 0.133) where sows fed DFM returned to estrus 22 hours sooner than CON, but only 8 hours sooner when sows were fed the OA+DFM diet. In conclusion, feeding a Bacillus licheniformis DFM to sows may decrease pig born alive weight but reduce sow BW loss through 6.4% more lactation feed intake, quickening the return to estrus. Feeding the OA alone or in combination did not improve sow reproductive and litter growth performance in this study, and may require a larger sample size.

259 Effects of Saccharomyces Cerevisiae Fermentation Products on Lactating Sow’s Blood and Uterine Cytokine Profiles

This study evaluated the effects of a liquid prototype (LIQP) and dry (XPC®; Diamond V) Saccharomyces cerevisiae feed additives on blood and uterine cytokine profiles in sows (n = 40). On d 112 of pregnancy sows were allotted to dietary treatments: 1) Control diet (CON), 2) CON +15 mL of LIQP (LIQ), 3) CON +0.20% of XPC (DRY), and 4) DRY +15 mL of LIQP until d 7 post-farrowing (D+L). Interleukin (IL)-1β, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) were quantified from serum samples collected on d 112 of gestation, d 2 and 6 post-farrowing, and from uterine fluid collected on d 2, 4, and 6 post-farrowing. Serum C-Reactive protein (CRP) and haptoglobin concentrations were evaluated. No interactions between treatments and day of collection were observed (P &gt; 0.13). LIQ and D+L sows had the greatest serum IL-10 concentration (P &lt; 0.001) and sows fed CON tended to have lower concentration of IL-8 (P &lt; 0.06) vs. other treatments. Serum CRP concentrations were greatest on d 2 (P &lt; 0.001), serum IL-10 (P &lt; 0.04) and IL-4 (P &lt; 0.07) linearly decreased while serum haptoglobin (P &lt; 0.02) and INF-γ (P &lt; 0.001) linearly increased post-farrowing. In the uterine fluid, LIQ and D+L sows had greater INF-γ (P = 0.04) concentrations and CON tended to have the least concentration of TNF-α (P = 0.08). Uterine fluid IL-1 tended to linearly increase (P &lt; 0.07) and IL-6 linearly decrease (P &lt; 0.01) post-farrowing. No strong correlations were detected between cytokines in the serum and uterine fluid within day. LIQ sows had the greatest daily feed intake and CON the least during the first week of lactation (P = 0.04). Providing LIQP post-farrowing to sows modified immune response increasing both pro- and anti-inflammatory cytokines in serum and uterine fluid in an independent manner, allowing animals a quicker recovery and increased feed intake.

242 Evaluation of a DFM and OA, Alone or in Combination, on Sow Offspring’s Nursery Growth Performance

Progeny from sows fed diets containing a Bacillus licheniformis direct-fed microbial (DFM), an organic acid blend of medium and short chain fatty acids (OA), DFM+OA, or a control (CON) diet from d80 of gestation until weaning were used to determine if feeding CON, DFM, OA, or DFM+OA to the dam and/or progeny post-weaning improved nursery growth performance. Weaned pigs from 47 dams (n = 384, Initial BW=6.15 kg) were blocked by initial BW and sex and allotted (6 pigs/pen, 8 pens/treatment) to one of 8 nursery treatments. Pigs from CON sows were fed a negative (NC; no antibiotics, pharmacological Zn or Cu) or positive [PC; Neo-Terramycin phases 1 and 2 (827 and 551 ppm) and Carbadox phase 3 (55 ppm)] control diet. Pigs from sows fed DFM, OA, or DFM+OA were fed the NC diet or a diet representative of their dam. Diets with DFM contained 1.6x109 CFU/kg DFM and diets with OA contained 0.5, 0.4, and 0.3% OA in phases 1–3, respectively. Weaning weight was used as a covariate for nursery performance. For all phases and overall, PC fed pigs had greater ADG, ADFI, and G:F (P &lt; 0.05). Feeding DFM or OA in sow diets improved (interaction; P&lt; 0.042) nursery pig G:F, but DFM+OA offspring had no improvement for d7–14, 0–14, and 0–21 G:F. Feeding DFM or OA to sows and their progeny decreased ADFI (interaction; P &lt; 0.042) but improved G:F (interaction; P &lt; 0.028) for d7–14 and 0–14 with DFM+OA having no improvement above CON. For d14–21 and 0–21, feeding DFM or OA to sows and their progeny decreased ADFI whereas DFM+OA increased ADFI above CON (interaction; P &lt; 0.019). In conclusion, feeding DFM or OA to sows or their offspring may improve nursery feed efficiency and feeding DFM+OA diet to sows and their progeny may increase ADFI late in the nursery period.

56 The Effect of a Developmental Bacillus Direct-fed Microbial on Nursery Pig Growth Performance and Health

A developmental Bacillus based direct-fed microbial (DFM) was added to nursery pig diets to evaluate the effect on growth and health in two 35-d randomized complete block design experiments blocked on initial BW and sex. Experiment 1 used 315 weaned pigs (20.1 d of age; 6.11 kg initial BW) allotted to one of three diets: 1) Negative Control (NC; no antibiotics but with pharmacological Zn or Cu), 2) NC+DFM 0.55x109CFU, 3) NC+DFM 1.1x109CFU. Experiment 2 used 376 weaned pigs (17.8 d of age; 5.99 kg initial BW) allotted to one of four diets, the same 3 diets from Experiment 1 plus a lower inclusion rate: 4) NC+DFM 0.275x109CFU. Both studies had 15 replicates/treatment, 6–7 pigs/pen. Pigs were budget fed phase 1–3 diets (1.13 kg/pig; 2.72 kg/pig; and 6.35 kg/pig, respectively) and ad libitum fed Phase 4 diet to d35. For Experiment 1, during week 1 pigs fed the DFM tended to linearly decrease ADFI (P = 0.086) and linearly increase G:F (P = 0.085). During day 21–35 of Experiment 1 pigs fed DFM linearly increased ADG (P = 0.035) and quadratically increased ADFI (P = 0.027). Overall for experiment 1, ADG (P = 0.114) and ADFI (P = 0.104) tended to quadratically increase and G:F linearly increased (P = 0.012) with increasing concentrations of DFM. Experiment 2; during week 1 and 3 ADFI (P = 0.084, P = 0.050, respectively) quadratically increased and G:F (P = 0.081; P = 0.022, respectively) quadratically decreased as DFM increased in the diet. During d21–35 of experiment 2, ADG (P = 0.064) quadratically increased and G:F (P = 0.012) quadratically decreased as DFM increased. Overall for Experiment 2 ADFI numerically increased (4.3%) with no increase in ADG, resulting in a quadratic decrease in G:F (P = 0.010) as the DFM increased in the diet. Summarizing these two studies, the DFM product had its greatest effect increasing ADFI while inconsistently impacting gain and efficiency.

PSVI-17 The Effect of Dacitic Tuff Breccia Alone or in Combination with Poultry By-products on Nursery Pig Growth Performance

Dacitic tuff breccia (DTB) and poultry by-products (PBP) were added to nursery pig diets to evaluate their effects on growth performance in a 35 d experiment. A randomized complete block design based on BW and sex was used. Newly weaned pigs (N=564, 20.1 d of age, 6.18±0.006 kg initial BW) allotted to four diets (15 replicates/treatment; 9 or 10 pigs/pen): 1) Negative control (NC; no DTB or PBP), 2) NC+DTB (0.5% inclusion), 3) NC+PBP (4% chicken by-product meal + 2% feather meal – replacing fishmeal, corn, and synthetic amino acids in the NC), 4) NC+DTB+PBP. Phase 1–3 were each 7-d and Phase 4 was from d21-35. During week one there were no differences (P &gt;0.10) among treatments. In week 2, pigs fed DTB tended to increase ADG (323 vs. 303 g/d; P=0.068) and ADFI (376 vs. 356 g/d; P=0.055) compared to pigs not fed DTB and pigs fed PBP tended to have increased ADG (P=0.093). In week 3 pigs fed PBP had reduced ADG (460 vs 483 g/d; P=0.011) and G:F (0.689 vs. 0.723; P&lt; 0.001), and there tended to be an interaction for G:F (P=0.083) with DTB improving G:F when fed in combination with PBP but reducing G:F in the control diet. In week 4, feeding PBP decreased ADG (384 vs 415 g/d; P&lt; 0.01) and ADFI (629 vs 666 g/d; P&lt; 0.01) compared to pigs fed no PBP. There were no differences among treatments during week 5. For Phase 4 (d21-35) pigs fed PBP had decreased ADG (479 vs 497 g/d; P=0.041) and tended to have reduced ADFI (P=0.092) compared to pigs fed no PBP. Overall (d 0–35), there were no significant differences among treatments. In conclusion, DTB improved nursery pig growth performance early, however, pigs fed PBP had decreased ADG and feed efficiency late in the nursery period.

PSIX-6 Effect of dacitic tuff breccia in nursery diets on pig growth performance, blood parameters, and intestinal morphology

Trace element and mineral intake are important for proper function of the immune system and various metabolic processes. The objective of this experiment was to evaluate the effect of a dacitic tuff breccia (DTB), classified as a hydrated sodium calcium aluminosilicate, in the diet of nursery pigs. Dietary treatments were: 1) Control diet (CON), 2) CON + 0.25% DTB (DTB1), and 3) CON + 0.50% DTB (DTB2). Pigs (6.79 + 0.064 kg; 26d of age) were individually housed and fed dietary treatments for 21 d (n=48; 16/trt). At the end of the experiment, blood, jejunal, and ileal samples were collected for a typical metabolic panel and basic histologic and morphologic measurements. DTB2 fed pigs tended (P=0.07) to have greater ADG than CON and DTB1 fed pigs (392, 397, 430g/d for CON, DTB1, DTB2, respectively), and greater (P=0.008) ADFI (591, 592, 669g/d for CON, DTB1, DTB2, respectively). Gain:Feed was not different (P=0.75) among treatments (0.655, 0.663, 0.644 for CON, DTB1, DTB2, respectively). Crypt depth in the jejunum was greater (P=0.04) for DTB1 compared to CON fed pigs but did not differ from DTB2 fed pigs (254.7, 292.0, 275.6mm for CON, DTB1, DTB2, respectively). Villous height, villous:crypt, number of goblet cells and intraepithelial lymphocytes did not differ among treatments in both ileum and jejunum (P &gt;0.17). Total white blood cell (WBC) count did not differ (P &gt;0.10). However, the proportion of WBC that were monocytes was lower (P=0.024) in DTB1 compared to CON and DTB2 fed pigs (1.27, 0.79, 1.45% for CON, DTB1, DTB2, respectively). Blood Urea Nitrogen (BUN) concentration tended (P=0.06) to be linearly decreased with increasing DTB concentrations (9.27, 8.80, 7.75mg/dL). DTB inclusion at 0.5% in nursery pig diets tended to improve growth performance, while inclusion at 0.25% increased jejunal crypt depth and reduced monocytes:WBC and increasing DTB concentrations tended to decreased BUN linearly.

185 Effect of dacitic tuff breccia in nursery diets on pig growth performance and nutrient digestibility

For proper function of many metabolic processes trace element and mineral intake is important. The objective of this experiment was to evaluate the addition of a dacitic tuff breccia (DTB), a hydrated sodium calcium aluminosilicate, on nursery pig growth and nutrient digestibility. Dietary treatments were: 1) Control (CON) and 2) CON+0.50% DTB (DTB). Pigs (7.73±0.205 kg; 26 d of age) were individually housed and fed for 20d (n=24, 12/trt). Nutrient digestibility was evaluated using individual metabolism pens for 3d total collection of feces and urine during the last week of evaluation. DTB had no effect on pig performance during week 1 (P &gt;0.28). Week 2 ADG (128 versus 302 g/d; P=0.02), BW (10.63 versus 11.77 kg; P=0.03), and G:F (0.275 versus 0.608; P=0.02) were improved for DTB compared to CON fed pigs. Week 3 ADFI was greater for DTB fed pigs compared to CON (642 vs 768 g/d; P=0.01). Overall (d0-20), DTB fed pigs had greater ADG (279 versus 352 g/d; P=0.04), final BW (13.3 versus 14.8 kg; P=0.04), and numerically greater ADFI (497 versus 558 g/d; P=0.16) and G:F (0.562 versus 0.624; P=0.22) compared to CON. During the collection period, ADG was numerically increased (396 versus 427 g/d; P=0.69) and ADFI (544 vs 668 g/d; P=0.03) was greater for DTB versus CON fed pigs. Nutrient digestibility was not affected by inclusion of DTB in the diet (P &gt;0.05). Digestibility coefficients for CON and DTB, respectively, were: 0.863 and 0.856 for DM; 0.842 and 0.842 for digestible energy; 0.824 and 0.814 for nitrogen; 0.701 and 0.667 for phosphorus; 0.873 and 0.816 for sodium; 0.481 and 0.431 for zinc; 0.517 and 0.458 for iron; and 0.438 and 0.392 for manganese. DTB in nursery pig diets improved growth performance and tended to improve feed intake, but had no effect on nutrient digestibility.

30 Uterine flushing as a non-invasive method to access inflammatory cytokines in sows reproductive tract after parturition

Inflammatory mediators, such as cytokines, can reduce feed intake and drastically modify the partitioning of nutrients. Thus, it may increase the animal’s maintenance requirements, reduce milk production and piglet growth, impact reproductive performance, and reduce sow lifetime productivity. The objective of this experiment was to evaluate a non-invasive method, not tested before in swine, to assess cytokine profiles from post-partum uterine lavage. The uteri of second and third parity sows (n=14) were flushed with sterile saline solution (0.9%) on days 2, 4, and 14 post-parturition. An artificial insemination (AI) catheter, in its plastic covering, to avoid vaginal contents, was inserted through the vagina into the cervix. A flexible inner catheter was passed through the outer AI catheter and into the uterine horn. Sterile saline (30-40 mL) was flushed through the inner catheter into one uterine horn. After inner catheter removal, a tube was attached to the end of the outer AI catheter to allow collection of the natural back-flow of uterine lavage fluid (avg 24.7% recovery). Uterine fluid collected was immediately centrifuged and the supernatant stored at -20°C. Samples were freeze-dried, re-suspended in sterile saline (2 mL), and stored at -80°C. Cytokine profiles of the uterine fluid were evaluated using a multiplex ELISA panel including interleukin (IL)-1β, IL-6, IL-8, IL-4, IL-10, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ). Cytokine concentrations were calculated relative to protein content (pg/mg of protein). IFN-γ and TNF-α were lower than the limit of detection in most samples (5/38 and 1/38, respectively). IL-4 and IL-10 concentrations did not differ among days of collection (P &gt;0.14). IL-8 was greater on day 4 than on days 2 or 14 (P&lt; 0.05). IL-1β and IL-6 were greater on days 2 and 4 than on day 14 (P&lt; 0.05). Uterine flushing is a novel non-invasive method to access uterine inflammatory cytokines in sows.

154 Evaluating the effects of prophylactic antibiotics on intestinal health in pigs given a corticotropin-releasing factor antagonist during weaning and transport

Prophylactic antibiotics improve intestinal health in pigs; however, it is unknown whether their efficacy interacts with a pig’s stress response following weaning and transport. The study objective was to determine whether a corticotropin-releasing factor (CRF) antagonist would impact the efficacy of prophylactic antibiotics on improving intestinal health in transported weaned pigs. Mixed-sex pigs (n = 56; 5.70 ± 1.05 kg BW) were weaned (20.49 ± 0.64 d), a blood sample was taken, pigs were given an i.p. injection of saline (SAL) or a CRF antagonist (CRFA; 30 µg/kg BW; Astressin B), and then were transported for 12 h. Pigs were given a second and third i.p. injection at 6 and 12 h of transport, respectively. Following transport, 4 SAL and 4 CRFA pigs were blood sampled and euthanized. The remaining 48 pigs were individually housed and assigned to an antibiotic [A; chlortetracycline (441 ppm) + tiamulin (38.6 ppm)] or no antibiotic (NA) diet treatment balanced by injection treatment (n = 12 pigs/treatment combination). Blood was collected at 12 h and on d 3, 7, and 14 and pigs were euthanized on d 7 (n = 24) and d 14 (n = 24) post-weaning and transport. Plasma adrenocorticotropic hormone was reduced overall (P = 0.05; 9.1%) in CRFA versus SAL pigs. On d 7, jejunal villus height was greater (P = 0.04; 33%) in A versus NA pigs. Jejunal zonula occludens-1 (58.8%) and ileal claudin-1 (100.5%) mRNA abundance tended to be increased (P = 0.09) in CRFA+NA versus SAL+NA pigs on d 7. On d 14, jejunal tumor necrosis factor-alpha mRNA abundance was reduced (P = 0.02; 29.9%) in A versus NA pigs and jejunal glucagon-like peptide-2 mRNA abundance was increased (P = 0.03) in CRFA+NA versus SAL+NA (48.4%) and SAL+A versus SAL+NA (55.8%) pigs. No intestinal health parameter differences were detected (P &gt; 0.05) between CRFA+NA and SAL+A pigs. In conclusion, CRFA and A impacted weaned pig intestinal health measures at similar levels.

Measuring piglet castration pain using linear and non-linear measures of heart rate variability

The purpose of this study was to evaluate whether linear and non-linear measures of heart rate variability (HRV) could be used as indicators of piglet castration pain. Thirty piglets were allocated to 1 of 4 treatments: i) sham castrated HRV (SHRV; n = 8); ii) surgical castrated HRV (CHRV; n = 7); iii) sham castrated blood collection (SBC; n = 7); or iv) surgical castrated blood collection (CBC; n = 8). Piglets in the SHRV and CHRV treatment groups underwent a 1-h HRV and postural behaviour evaluation on day –1, day 0 (castration treatment), day 1 and day 3 of the experimental procedure. Piglets in the SBC and CBC groups underwent blood collection for serum cortisol analysis at –0.5, 1, 2, 3, 24, 48 and 72 h relative to castration treatment. Castrated piglets (CHRV) exhibited greater low to high frequency ratio, lower sample entropy and greater percent determinism compared to SHRV piglets, indicating greater pain-related stress due to the surgical castration procedure. Serum cortisol was greater in CBC pigs at 1 h post-castration compared to SBC piglets. No effect of treatment was found for amount of time spent lying post-castration. In conclusion, surgically castrated pigs exhibited greater pain-related stress than their sham castrated counterparts. Additionally, non-linear HRV measures seem to complement traditional linear HRV measures and may be valuable for assessing pain-related stress in future studies investigating swine welfare.

Time course determination of the effects of rapid and gradual cooling after acute hyperthermia on body temperature and intestinal integrity in pigs

Rapid cooling after acute hyperthermia may cause a sustained increase in body temperature and exacerbate intestinal damage in pigs. Therefore, the study objective was to evaluate the temporal effects of rapid and gradual cooling on body temperature response and intestinal integrity after acute hyperthermia in pigs. In three repetitions, 54 pigs [83.3 ± 6.7 kg initial body weight (BW)], balanced by sex were exposed to thermoneutral conditions for 6 h (TN; n = 6 pigs/repetition; 21.1 ± 2.0°C), or heat stress conditions (HS; 39.3 ± 1.6°C) for 3 h, followed by a 3 h recovery period of gradual cooling [HSGC; n = 6 pigs/repetition; gradual decrease from HS to TN conditions] or rapid cooling [HSRC; n = 6 pigs/repetition; rapid TN exposure and cold water (4.0°C) dousing every 30 min for 1.5 h]. Feed was withheld throughout the entire 6 h period, but water was provided ad libitum. Gastrointestinal (T_GI) and rectal (T_R) temperatures were recorded every 15 min during the HS and recovery periods. Six pigs per repetition (n = 2/treatment) were euthanized and jejunal and ileal samples were collected for histology immediately after (d 0), 2 d after, and 4 d after the recovery period. Data were analyzed using PROC MIXED in SAS 9.4. Overall, rapid cooling reduced T_R and T_GI (P < 0.01; 0.95°C and 0.74°C, respectively) compared to gradual cooling. Jejunal villus height was reduced overall (P = 0.02; 14.01%) in HSGC compared to HSRC and TN pigs. Jejunal villus height-to-crypt depth ratio was reduced overall (P = 0.05; 16.76%) in HSGC compared to TN pigs. Ileal villus height was reduced overall (P < 0.01; 16.95%) in HSGC compared to HSRC and TN pigs. No other intestinal morphology differences were detected. In summary, HSRC did not cause a sustained increase in body temperature and did not negatively impact biomarkers of intestinal integrity in pigs.

Effects of antibiotic-free pig rearing on ammonia emissions from five pairs of swine rooms in a wean-to-finish experiment

Antibiotic use and ammonia (NH₃) emissions during animal production are two environmental issues of worldwide concern. However, the role of antibiotics on NH₃ emissions is still unknown. This study evaluated the effects of rearing pigs without antibiotics on NH₃ emissions from a swine experimental building starting with 657 piglets during a wean-to-finish production cycle of 154 days. Pigs were reared in two groups of 10 rooms that were divided into five 2-room pairs (P1-P5) and fed in nine dietary phases. Each pair consisted of one room without antibiotics (no antibiotics in the diet, water, or injectable) and another room as a positive control. Control animals were fed diets containing carbadox-10 (phases 1-4), chlortetracycline (CTC, phase 5), lincomix (phases 6-7), and tylan 40 (phases 8-9). Temperatures in the pig living space and the under-floor manure pit headspace were continuously measured. Ventilation rates at all wall fans and pit fans were obtained by continuous monitoring. Ammonia concentrations in the wall and pit fan exhaust air, and in room inlet air were measured with two multi-gas monitors. Only days that contained at least 18 h of data each day were validated and used. The study generated 1337 room-days of valid data of NH₃ emission rates, with a data completeness of 88.6%. Daily mean NH₃ emission patterns demonstrated large variations between the paired rooms and among different pairs. Within the individual 2-room pairs, no NH₃ emission differences were found in P1 (rooms 1 and 2, p = 0.34) and P2 (rooms 3 and 4, p = 0.44). Significant differences were found in P3-P5 (p < 0.01). The antibiotic-free rooms emitted more NH₃ from P3 and P4, but less NH₃ from P5. However, the combined cycle mean NH₃ emissions from the group of five antibiotic-free rooms and the group of five control rooms were 41.6 ± 10.5 and 39.4 ± 10.6 g d^-1 AU^-1 (mean ± standard deviation. AU = 500 kg live body weight), respectively. Therefore, there was no statistical difference in combined cycle mean NH₃ emissions from rearing pigs with or without antibiotics (p = 0.78). This study also revealed that experiments with multiple replicates and long NH₃ monitoring durations were necessary to avoid potential misinterpretation of experimental results.

356 Young Scholar Presentation: An applied approach to studying heat stress: Effects of cyclic heat and zinc supplementation on body temperature, gut health, and pork quality

Heat stress (HS) has depletory effects on intestinal morphology, induces metabolic changes, and disposes pigs to oxidative stress. Zinc has roles in gut health, nutrient and insulin mediated metabolism. To better understand the effects of cyclic heat and dietary Zn supplementation on gut integrity, carcass composition, and pork quality, commercial crossbred mixed-sex pigs (n = 400; initially 72.2 kg) were housed under either thermoneutral (TN; 18.9–16.7°C) or cycling HS conditions simulating chronic summer heat (30°C/26.7°C for 12h:12h on days 24–65) with acute heat periods of 32-33°C/29-30°C for 12h:12h on days 21–24, 42–45, and 63–65. Treatments were arranged in a 2×2×2 factorial with main effects of environment (HS vs. TN), added Zn level (50 vs. 130 mg/kg available Zn), and added Zn source (inorganic from ZnO vs. organic from Availa®Zn; Zinpro Corp, Eden Prairie, MN). Relative to TN, HS elevated (P < 0.050) body temperatures during the growing period. Heat stress was correlated with ileal villus height (r=-0.51, P = 0.015) and HSP-70 expression (r=0.46, P = 0.041). Growth was reduced such that carcasses from HS pigs were lighter (P = 0.011) and exhibited improved carcass quality with higher (P = 0.001) 24-hour loin pH, decreased (P = 0.034) drip loss, and greater (P < 0.050) subjective color and firmness scores compared to TN carcasses. Relative to TN, loin chops and sausage patties manufactured from the HS carcasses had similar oxidative stability (CIE L*a*b* color, 2-thiobarbituric acid reactive substances) throughout a 10-day simulated retail display. The HS induced fatty acid profile differences in the pork product but were not sufficient to shift IV (P > 0.10). Belly firmness and slice lean were also unaffected (P > 0.10) by HS. Zinc supplementation had minimal impact on the carcass quality characteristics studied. Further research is necessary to better understand the impact of HS duration, combination with additional stressors, and refine the ability to utilize thermal monitoring to manage negative impacts of HS.

146 Effects of feeding soluble fiber (dextrin) to pigs pre- and post-weaning on growth performance and volatile fatty acid (VFA) production

Thirty-two barrows were used in a 35-d experiment with the objective of evaluating effects of supplemental soluble fiber (dextrin) pre- and post-weaning on growth performance and VFA production. Pigs were blocked by genetics and BW, and randomly allotted to treatments in a 2x2 factorial design with or without fiber pre-weaning and with or without fiber post-weaning. Fiber was suspended in chocolate milk and administered orally through a syringe from 14 d prior to weaning until 4 d post-weaning, after which it was included in the diet at 1%. At weaning, pigs were group housed by treatment and allowed ad libitum access to a common starter diet. On d 4 post-weaning, pigs were moved to individual pens and fed diets with or without 1% fiber. Weights and feed intake were recorded 14 and 3 d prior to weaning and on d 0, 4, 11, and 21 post-weaning. On d 21 post-weaning, pigs were euthanized, and large intestine contents were collected for VFA analysis. Data were analyzed using the GLM procedure of SAS with pig as the experimental unit. Growth performance was not affected (P > 0.10) by treatment. A trend for an interaction of pre- and post-weaning fiber supplementation was observed for acetate (P = 0.052) and butyrate (P = 0.087) concentrations in large intestine contents. Pigs fed fiber only in the nursery had the highest acetate concentration, while pigs never receiving fiber had the lowest concentration. Pre-weaning fiber supplementation followed by no fiber in the nursery resulted in the highest butyrate concentrations with all other treatments being similar. Fiber supplementation pre-weaning tended (P = 0.053) to reduce isobutyrate concentrations. Pigs not receiving fiber post-weaning had increased valerate concentrations (P = 0.0245). There were no changes observed in propionate or isovalerate concentrations (P > 0.10). Fiber supplementation caused alterations in VFA concentrations when fed during pre- and post-weaning, indicating possible shifts in the microbiome, immune status and barrier function of the intestinal tract.

Short communication: Assessment of disbudding pain in dairy calves using nonlinear measures of heart rate variability

The purpose of this study was to evaluate whether pain-related stress caused by disbudding could be detected using nonlinear measures of heart rate variability (HRV). Twenty-five female Holstein calves (4-7 wk of age) were randomly assigned to 1 of 3 treatments: (1) sham disbud (SHAM; n = 9), (2) disbud with lidocaine-meloxicam pain mitigation (MED; n = 8), or (3) disbud without pain mitigation (NoMED; n = 8). Heart rate variability (sample entropy, percentage determinism, percentage recurrence, or mean length of diagonal lines in a recurrence plot) was recorded on d -1, 0, 1, 3, and 5 relative to the experimental procedure, with disbudding taking place on d 0. The short-term detrended fluctuation analysis scaling exponent was greater in MED calves than in SHAM calves, indicating a greater stress response to the disbudding procedure regardless of pain mitigation. These results indicate that calves in the MED group may have experienced pain-related stress as a result of the disbudding procedure. The remaining nonlinear HRV measures did not differ by treatment. Future research on this topic should address additional potential confounding factors, such as the effect of pain-mitigating drugs on autonomic function or the influence of the autonomic nervous system on wound healing, that may prohibit HRV measurement as an indicator of disbudding pain severity.

Hydrogen sulfide emissions from a swine building affected by dietary crude protein

Hydrogen sulfide (H₂S) is a toxic air pollutant at animal facilities; but the understanding of its generation and emission processes has been limited. This paper studied H₂S emissions during a complete cycle of wean-finish pigs from a research building, where 12 pig rooms were divided into three groups that were fed with standard feed (control), and 2.1-3.8% (T₁) and 4.4-7.8% (T₂) reduced dietary crude protein (CP) feed. The group cycle mean H₂S emission rates were 4.0 ± 2.9, 4.3 ± 3.2, and 5.4 ± 4.0 g d^-1 AU^-1 (Animal Unit = 500 kg live mass), respectively, for the control, T₁, and T₂ groups. Emissions of H₂S were promoted by 10.0 and 36.7%, respectively, for the T₁ and T₂ groups (p < 0.001), although large variabilities existed in the emissions from different rooms within the same groups. The enhanced H₂S emissions from the T₁ and T₂ groups were related to the reduced manure pH and were possibly affected through a number of pathways, which could involve volatile fatty acids and nitrogen concentrations, and microbial activities in manure.

Mitigation of ammonia emissions from pig production using reduced dietary crude protein with amino acid supplementation

To mitigate ammonia (NH₃) emissions from pig production and understand dynamic emission profiles, reduced dietary crude protein (CP) with amino acid supplementation was studied with 720 pigs in a 12-room research building for 155days that covered from weaned to finishing stages. The pigs were divided into three 4-room groups and fed with 2.1-3.8% reduced CP (T₁), 4.4-7.8% reduced CP (T₂), and standard (control) diets, respectively. Compared with the control group, T₁ and T₂ decreased manure volumes and manure NH₄⁺-N concentrations. Group-mean NH₃ emission from the control group was 68.9gd^-1AU^-1 (AU=500kg live mass). Emissions from T₁ (46.7gd^-1AU^-1) and T₂ (29.8gd^-1AU^-1) were reduced by 33.0% and 57.2% (p<0.05), respectively. Dynamic peak NH₃ emissions appeared during the third nursery phase for T₁ and T₂, but delayed to the first grower phase for the control group.

Preventing, treating, and predicting barbering: A fundamental role for biomarkers of oxidative stress in a mouse model of Trichotillomania

Barbering, where a “barber” mouse plucks hair from its cagemates or itself, is both a spontaneously occurring abnormal behavior in mice and a well validated model of Trichotillomania (TTM). N-Acetylcysteine, (NAC) a cysteine derived food additive, is remarkably effective in treating TTM patients, but its mechanism of action is unknown. Reactive Oxygen Species (ROS), also known as free radicals, form as a natural byproduct of the normal metabolism of oxygen. Under normal circumstances, cells are able to defend themselves against ROS damage with antioxidant pathways. NAC is the precursor to the main antioxidant produced to defend the brain. Therefore, we hypothesized that barbering is a disease of oxidative stress, whereby ROS and/or a failure of antioxidant defenses leads to neuronal damage that induces barbering in susceptible animals. We tested this hypothesis in 32 female C57BL/6J mice by treating half with 1g/kg BW/day of NAC in their diet, and testing for protection against developing barbering behavior and curing of barbering behavior, and simultaneously testing for a panel of biomarkers of oxidative stress. NAC reduced the chance that mice would be barbers, and this effect did not differ between healthy (i.e. prevention) and affected animals (i.e. cure). Barbering animals had elevated urinary antioxidant capacity, indicative of oxidative stress, at all timepoints. Additionally, after treatment the risk of barbering increased with decreasing hydroxy-2′-deoxyguanosine (8-OHdG) levels, and with increasing glutathione (GSH) and oxidized glutathione (GSSG) levels, further indicating that barbering mice were under oxidative stress regardless of treatment with NAC. We did not find compelling evidence that urinary total antioxidant capacity, or urinary 8-OHdG, could predict response to NAC treatment. We conclude that NAC is effective in preventing and/or curing barbering at least in part by promoting GSH synthesis, thereby preventing oxidative damage.

Effects of dirty housing and a Typhimurium DT104 challenge on pig growth performance, diet utilization efficiency, and gas emissions from stored manure

The objectives of this study were to elucidate the effects of a dirty environment and a challenge plus associated environmental contamination on pig growth performance, diet utilization efficiency, and gas emissions (CO, NH, CH, NO, and HS) from stored manure. Twenty-four weaned barrows, aged 31 d at initiation of the trial, were randomly allotted to 3 different treatments in a completely randomized design. Treatments were: pigs housed in cages with manure removed and cages washed daily (Clean); pigs housed in cages sprayed daily with manure slurry mixtures (Dirty); or pigs challenged with Typhimurium DT104 and housed in cages that were not washed, but manure was removed daily ( challenge). Rectal temperature, body weight, daily feed intake, manure output, manure composition, and gas emissions from stored manure were measured throughout the 24-d animal phase. The Dirty and challenge treatments were statistically compared to the Clean treatment to evaluate individual effects. Dirty housing tended to decrease ADG from d 1 to 24 ( = 0.06) but there were no other effects on pig performance compared with the Clean treatment. In contrast, a challenge was associated with a marked reduction in each of the measured indicators of pig performance. challenge increased the carbon to nitrogen ratio, ether extract, and lignin concentrations in excreted manure ( = 0.02, 0.01, 0.003, respectively), and increased manure and head space temperatures in manure tanks ( < 0.0001). Gas emissions from stored manure of pigs on the Dirty or treatments were increased for each of the measured gases as compared to the Clean treatment ( < 0.01) when expressed per unit of BW gain. When gas emissions from manure of pigs housed in the Dirty treatment were expressed per unit of manure volatile solids (VS), they were increased for NH, CH, and HS ( < 0.02). challenge was associated with increased emissions of CO, and NO and decreased emissions of HS per kilogram manure VS compared to the Clean treatment ( = 0.06, 0.03, 0.04, respectively). Collectively, these results indicated that a challenge and associated housing contamination caused depressed growth rate and increased manure gas emissions, while exposure to a Dirty environment slightly reduced growth performance and clearly increased manure gas emissions per unit of BW gain as compared to Clean control.

Effects of porcine reproductive and respiratory syndrome virus on pig growth, diet utilization efficiency, and gas release from stored manure

The objectives of this study were to examine the effects of porcine reproductive and respiratory syndrome virus (PRRSV) infection and vaccination on pig growth, dietary nutrient efficiency of utilization, manure output, and emissions of CO, CH, HS, NO, and NH gases from stored manure. Forty-eight pigs, aged 21 d at the start of the study, were subjected to 1 of 4 treatment combinations arranged in a 2 × 2 factorial design with main factors of PRRSV vaccination and PRRSV infection. Body weight, ADFI, manure output, and nutrient efficiency of utilization were assessed and gas emissions from stored manure were determined daily from 50 to 78 d of age and for 24 d after completion of the animal phase. Infection with PRRSV markedly reduced final BW, ADG, and ADFI ( < 0.01) and reduced efficiencies of ADF and ether extract utilization ( = 0.05 and = 0.02, respectively) regardless of vaccination status. No significant treatment effects were found on manure output, manure pH, efficiencies of lignin utilization, and N retention. Infecting pigs with PRRSV increased daily manure CO emission per pig ( = 0.01). There was an interaction between immunization and infection for NO per pig with manure from uninfected, vaccinated pigs producing as much as the manure from infected, vaccinated pigs whereas there was a difference by PRRSV infection state for nonvaccinated pigs. There were also interactions between treatments for HS and NO emissions per kilogram of manure volatile solids excreted ( = 0.01 and = 0.0001, respectively) with the same pattern as for NO per pig; that is, the vaccinated pigs had similar rates of emission regardless of infection state. Pigs infected with PRRSV increased NO nitrogen per kilogram of total N excreted compared with noninfected groups ( = 0.03). Collectively, these results indicated that PRRSV infection caused decreased growth rates and nutrient utilization efficiency and increased gas emissions from stored manure.

Effect of High-Calcium Diet on Coronary Artery Disease in Ossabaw Miniature Swine With Metabolic Syndrome

Background

Calcium is a shortfall essential nutrient that has been a mainstay of osteoporosis management. Recent and limited findings have prompted concern about the contribution of calcium supplementation to cardiovascular risk. A proposed mechanism is through the acceleration of coronary artery calcification. Determining causality between calcium intake and coronary artery calcification has been hindered by a lack of sensitive methodology to monitor early vascular calcium accumulation. The primary study aim was to assess the impact of high calcium intake on coronary artery calcification using innovative calcium tracer kinetic modeling in Ossabaw swine with diet-induced metabolic syndrome. Secondary end points (in vitro wire myography, histopathology, intravascular ultrasound) assessed coronary disease.

Methods and Results

Pigs (n =24; aged ≈15 months) were fed an atherogenic diet with adequate calcium (0.33% by weight) or high calcium (1.90% from calcium carbonate or dairy) for 6 months. Following 5 months of feeding, all pigs were dosed intravenously with ⁴¹Ca, a rare isotope that can be measured in serum and tissues at a sensitivity of 10⁻¹⁸ mol/L by accelerator mass spectrometry. Kinetic modeling evaluated early coronary artery calcification using ⁴¹Ca values measured in serial blood samples (collected over 27 days) and coronary artery samples obtained at sacrifice. Serum disappearance of ⁴¹Ca and total coronary artery ⁴¹Ca accumulation did not differ among groups. Secondary end points demonstrated no treatment differences in coronary artery disease or function.

Conclusion

There was no detectable effect of high calcium diets (from dairy or calcium carbonate) on coronary artery calcium deposition in metabolic syndrome swine.

Controlling Salmonella infection in weanling pigs through water delivery of direct-fed microbials or organic acids: Part II. Effects on intestinal histology and active nutrient transport

The objective of this study was to evaluate the effects of water-delivered, direct-fed microbials (DFM) or organic acids on intestinal morphology and active nutrient absorption in weanling pigs after deliberate Salmonella infection. Pigs (n = 88) were weaned at 19 ± 2 d of age and assigned to 1 of the following treatments, which were administered for 14 d: 1) control diet; 2) control diet + DFM (Enterococcus faecium, Bacillus subtilis, and Bacillus licheniformis) in drinking water at 10(9) cfu/L for each strain of bacteria; 3) control diet + organic acid-based blend (predominantly propionic, acetic, and benzoic acids) in drinking water at 2.58 mL/L; and 4) control diet + 55 mg/kg carbadox. Pigs were challenged with 10(10) cfu Salmonella enterica var Typhimurium 6 d after commencement of treatments. Pigs (n = 22/d) were harvested before Salmonella challenge and on d 2, 4, and 8 after challenge. Duodenal, jejunal, and ileal mucosal tissues were sampled for measurement of villus height and crypt depth. Jejunal tissue was sampled for determination of active nutrient absorption in modified Ussing chambers. Duodenal villus height was greater in pigs fed in-feed antibiotic before infection (P < 0.05). Jejunal crypts were deeper in DFM- and acid-treated pigs on d 4 after infection compared with all other treatments (P < 0.05). Salmonella infection resulted in a linear decrease in phosphorus (P < 0.001) and glucose (P < 0.05) active transport, and an increase (P < 0.001) in glutamine uptake immediately after challenge. Salmonella infection reduced basal short-circuit current (I(sc)); however, water-delivered DFM or organic acid treatments caused greater basal I(sc) on d 2 after challenge than did carbadox. Carbachol-induced chloride ion secretion was greatest in negative control pigs before infection (P < 0.01) and DFM-treated pigs (P < 0.05) after infection. In conclusion, both the DFM and acidification treatments induced increases in basal active ion movement and jejunal crypt depth, which could be interpreted as responses consistent with increased Salmonella pathology, but none of the additives markedly affected intestinal absorptive and secretory function in response to Salmonella challenge.

Controlling Salmonella infection in weanling pigs through water delivery of direct-fed microbials or organic acids. Part I: effects on growth performance, microbial populations, and immune status

Pigs (n = 88) weaned at 19 ± 2 d of age were used in a 14-d study to evaluate the effects of water-delivered direct-fed microbials (DFM) or organic acids on growth, immune status, Salmonella infection and shedding, and intestinal microbial populations after intranasal inoculation of Salmonella Typhimurium (10(10) cfu/pig). Pigs were challenged with Salmonella 6 d after commencement of water treatments. Treatments were 1) control diet; 2) control diet + DFM (Enterococcus faecium, Bacillus subtilis, and Bacillus licheniformis) in drinking water at 10(9) cfu/L for each strain of bacteria; 3) control diet + an organic acid-based blend (predominantly propionic, acetic, and benzoic acid) in drinking water at 2.58 mL/L; and 4) control diet + 55 mg/kg of carbadox. Serum samples were taken on d 6, 8, 10, and 14 for determination of tumor necrosis factor α (TNFα) concentrations. Fecal samples were taken on d 0, 5, 7, and 11 for determination of Salmonella shedding and enumeration of coliforms. Pigs were euthanized on d 6, 8, 10, and 14. Intestinal and cecal tissue and digesta and mesenteric lymph nodes were sampled and analyzed for Salmonella. Duodenal, jejunal, and ileal mucosal scrapings were sampled for measurement of mucosal TNFα concentrations. Water delivery of DFM prevented a decline in ADG on d 2 to 6 postchallenge compared with the negative control (P < 0.05). Coliform counts tended to be greater (P = 0.09) in the cecum of the DFM treatment group on d 2 postinfection compared with the negative control and acid treatment groups. However, Salmonella prevalence in the feces, gastrointestinal tract, or lymph nodes was not affected by water delivery of acids or DFM. Serum and mucosal TNFα concentrations were not affected by treatment throughout the study with the exception of ileal concentrations on d 4 postchallenge, which were greater in the negative control group compared with all other treatments (P < 0.05). The in-feed antibiotic was the only treatment that reduced Salmonella prevalence and this was localized to the cecum on d 8 postinfection. In conclusion, the DFM and organic acid treatments used in this study offered little or no benefits to pigs infected with Salmonella and should not be considered under the constraints of this study as viable alternatives to in-feed antibiotics in a pathogen challenge situation.

Sodium-dependent phosphate uptake in the jejunum is post-transcriptionally regulated in pigs fed a low-phosphorus diet and is independent of dietary calcium concentration

In rodents, severe dietary P restriction increases active phosphate absorption by the intestine. However, it remains unknown if moderate dietary P restriction has a similar effect. Weanling pigs (n = 32; body weight 7.4 +/- 0.55 kg) were used in a 2 x 2 factorial design and fed dietary available P (aP) concentrations of 0.23 or 0.40% and Ca concentrations of 0.58 or 1.00% for 14 d. Diets were formulated on an aP basis instead of a total P basis, because pigs are unable to absorb phytate-P present in corn and soybean meal. Jejunal segments were mounted in modified Ussing chambers for determination of Na(+)-dependent nutrient transport. Intestinal mucosal scrapings were taken for RNA isolation and brush border membrane (BBM) vesicle isolation. Na(+)-dependent phosphate uptake and gene expression of Na-phosphate cotransporter IIb (NaPi-IIb), SGLT-1 (sodium/glucose cotransporter-1), and calbindin D(9k) and protein expression of NaPi-IIb were evaluated. Na(+)-dependent phosphate transport increased (P < 0.05) 46% as dietary aP concentration was decreased. However, increased Na(+)-dependent phosphate uptake was not accompanied by increased NaPi-IIb mRNA expression. Expression of NaPi-IIb protein in the BBM increased (P < 0.01) 84% in pigs fed low-P diets compared with pigs fed adequate-P diets. No dietary Ca effects or aP x Ca interactions were detected for Na-dependent P uptake, mRNA or protein expression of NaPi-IIb, or mRNA expression of calbindin D(9k). These data suggest that restricting dietary aP concentration by only 43% stimulates Na(+)-dependent phosphate uptake and expression of the NaPi-IIb protein in the BBM of the small intestine and through a post-transcriptional mechanism.

The digestive fate of Escherichia coli glutamate dehydrogenase deoxyribonucleic acid from transgenic corn in diets fed to weanling pigs

Corn containing genetically engineered plasmid DNA encoding an Escherichia coli glutamate dehydrogenase (gdhA) was fed to 19-d-old weanling swine to trace the digestive fate of the transgenic DNA. Eight pens of 8 pigs were fed a commercial (nongdhA) starter for 2 wk. One pig was randomly selected from each pen for 0-h control samples. The remaining 56 pigs were transitioned onto a corn-soybean meal diet and fed a diet containing 58% gdhA corn for approximately 1 wk; immediately thereafter, liver, 10th rib muscle, white blood cells, and plasma from the hepatic portal vein and ingesta from the stomach, distal ileum, and large intestine were collected. The DNA was extracted and the concentration determined via spectrophotometry. Polymerase chain reaction and gel electrophoresis were performed with primers designed to amplify 490 bp that included the plasmid's ligation site between the maize ubiquitin and the gdhA genes. The gdhA corn-derived DNA and diet served as positive assay controls, and conventional corn DNA and distilled water acted as negative assay controls. Detection limits were 0.99 fg of target DNA confounded with 500 ng of conventional corn DNA per each 20 &L reaction. Transgenic DNA was detected in 71.43% of the stomach and 1.79% of the ileal ingesta samples from treatment animals but was not detected in the large intestine, white blood cells, plasma, liver, or muscle samples. Transgenic DNA was not detected in any sample from 0-h control animals. Stomach and ileal ingesta samples were further analyzed using real-time PCR. With an estimated limit of detection of 1.049 ag/microL, 89.29% of the stomach ingesta samples were positive (average 1.56 fg target DNA). The proportion of transgenic DNA to total DNA differed between diet and stomach ingesta samples (P < 0.001). Despite the greater sensitivity of real-time PCR, target DNA was detected in only 1.79% of ileal ingesta. These data suggest that the gdhA transgene began degradation in the stomach and was nondetectable in the large intestine.

Effects of water and diet acidification with and without antibiotics on weanling pig growth and microbial shedding

Two 5-wk experiments were conducted to determine the effects of water and diet acidification with and without antibiotics on weanling pig growth performance and microbial shedding. In Exp. 1, 204 pigs (19.2 d of age) were used in a 3 x 2 factorial, with 3 dietary treatments fed with or without water acidification (2.58 mL/L of a propionic acid blend; KEM SAN, Kemin Americas, Des Moines, IA). Dietary treatments were: 1) control, 2) control + 55 ppm of carbadox (CB), and 3) dietary acid [DA; control + 0.4% organic acid-based blend (fumaric, lactate, citric, propionic, and benzoic acids; Kemin Americas)] on d 0 to 7 followed by 0.2% inorganic acid-based blend (phosphoric, fumaric, lactic, and citric acids; Kemin Americas) on d 7 to 34. In Exp. 2, 210 pigs (average 18.3 d of age) were fed 1 of 3 dietary treatments: 1) control, 2) control + 55 ppm of CB, and 3) control + 38.6 ppm of tiamulin + 441 ppm of chlortetracycline on d 0 to 7 followed by 110 ppm of chlortetracycline on d 7 to 35 (TC) with or without dietary acidification (same as Exp. 1) in a 3 x 2 factorial arrangement of treatments. For both experiments, the pigs were allotted based on genetics, sex, and initial BW [5.5 kg (Exp. 1) or 5.6 kg (Exp. 2)]. Pigs were housed at 6 or 7 (Exp. 1) and 7 (Exp. 2) pigs/pen. Treatments were fed in 3 phases: d 0 to 7, 7 to 21, and 21 to 35 (34 d, Exp. 1). Fecal grab samples were collected from 3 pigs/pen on d 6, 20, and 33 for measurement of pH and Escherichia coli. During phase 3 and overall in Exp. 1, pigs fed CB had greater (P < 0.001) ADG (overall ADG, 389 vs. 348, and 348 g/d, respectively), ADFI (P < 0.007, 608 vs. 559, and 554 g/d, respectively), and d 34 BW (P < 0.001, 18.8 vs. 17.3, and 17.3 kg, respectively) than pigs fed NC and DA. Phase 3 ADG was improved (P < 0.01) by water acidification across all diets. In Exp. 2, pigs fed CB and TC had greater ADG (P < 0.004; 315 and 303 vs. 270 g/d, respectively), ADFI (P < 0.01), and d 35 BW (P < 0.002; 16.7 and 16.2 vs. 15.1 kg, respectively) than pigs fed NC. There was a tendency (P < 0.08) for an improvement in ADG when DA was added to the NC or TC, but decreased ADG when DA was added to CB.

Effects of Acid LAC and Kem-Gest acid blends on growth performance and microbial shedding in weanling pigs1,2

Weanling pigs with mean initial BW of 6.04 kg (Exp.1) and 5.65 kg (Exp. 2) and mean age at weaning of 18.2 d (Exp. 1) and 17.7 d (Exp. 2) were used in two 5-wk experiments (Exp. 1, n = 180; Exp. 2, n = 300) to evaluate the effects of an organic acid blend (Acid LAC, Kemin Americas Inc., Des Moines, IA) and an inorganic/organic acid blend (Kem-Gest, Kemin Americas Inc.) on weanling pig growth performance and microbial shedding. In Exp. 1, the 5 dietary treatments were 1) negative control, 2) diet 1 + 55 ppm carbadox, 3) diet 1 + 0.4% Acid LAC, 4) diet 1 + 0.2% Kem-Gest, 5) diet 1 + 0.4% Acid LAC and 0.2% Kem-Gest. In Exp. 2, the 6 dietary treatments were diets 1 through 4 corresponding to Exp. 1, plus 5) sequence 1: 0.4% Acid LAC for 7 d followed by 0.2% Kem-Gest for 28 d, and 6) sequence 2: 0.2% Kem-Gest for 7 d followed by 0.4% Acid LAC for 28 d. Pigs were housed at 6 (Exp. 1) or 10 (Exp. 2) pigs/pen. Treatments were fed throughout the experiment in 3 phases: d 0 to 7, d 7 to 21, and d 21 to 35. In Exp. 1, there were no differences (P > 0.05) in ADG, ADFI, or G:F among the dietary treatments at any time during the study. In Exp. 2, throughout the study, pigs fed carbadox (diet 2) and sequence 1 (diet 5) diets had the greatest ADG (d 0 to 35; 262, 294, 257, 257, 292, and 261 g/d, diets 1 through 6, respectively; P < 0.05), greater ADFI than all other acid treatments (P < 0.05), and tended to have greater ADFI than diet 1 (P < 0.10). Fecal pH, Escherichia coli concentrations, and Salmonella presence were determined at d 6, 20, and 34 for Exp. 1, and on d 32 for Exp. 2. For both experiments, there was no effect of treatment on the presence of fecal Salmonella (P > 0.10) at any sampling time. In Exp. 1, fecal E. coli concentrations for pigs fed the carbadox (P < 0.05) diet were greater than for pigs fed the combination diet with 0.4% Acid LAC and 0.2% Kem-Gest on d 34, and the pigs fed the negative control diet tended (P < 0.10) to have greater fecal E. coli concentrations than those fed the combination diet on d 34. In Exp. 2, fecal pH of pigs fed sequence 1 tended to be greater than fecal pH of pigs fed diet 1, diet 4, or sequence 2 (P < 0.10), but there was no dietary effect on fecal E. coli. In Exp. 1, growth performance of pigs fed the Acid LAC and Kem-Gest diets was similar to each other and to that of the carbadox-fed pigs. Adding the combination of 0.4% Acid LAC and 0.2% Kem-Gest to nursery pig diets reduced ADFI and pig growth rate. In Exp. 2, pigs fed the acid sequence of Acid LAC-Kem-Gest had similar growth performance to pigs fed carbadox, and this novel dietary acid sequence may have merit as a replacement for antibiotics in the nursery phase.

Estimating equivalency values of microbial phytase for amino acids in growing and finishing pigs fitted with steered ileo-cecal valve cannulas

Ten crossbred barrows (48.3 +/- 2.3 kg of initial BW) fitted with steered ileo-cecal valve cannulas were used to investigate the effects of supplemental microbial phytase on the apparent ileal digestibilities (AID) of AA, Ca, P, N, and DM, and the apparent total tract digestibilities of Ca, P, N, and DM. All diets were corn-soybean meal-based, and contained 0.44% Ca and 0.40% total P. Diets 1, 2, and 3 contained 12.0, 11.1, and 10.2% CP, respectively. Diets 4 and 5 had the same ingredient composition as diet 3, plus 250 and 500 U/kg phytase (Natuphos), respectively. Pigs were randomly allotted to 1 of 5 dietary treatments in a paired 5 x 5 Latin square with an extra period to test for carryover effects. Each 14-d period consisted of a 7-d adjustment followed by a 3-d total collection, a 12-h ileal digesta collection, a 3-d readjustment, and a second 12-h ileal digesta collection. Pigs were housed individually in metabolism pens (1.2 x 1.2 m). Water was supplied ad libitum, and feed was supplied at a level of 9% of the metabolic BW (BW(0.75)) per day in 2 equal daily feedings. As the dietary CP concentration increased, the AID of CP and all AA measured increased linearly (P < 0.05) with the exception of proline. In addition, the apparent total tract digestibilities (grams per day) and retention of N (grams per day) increased linearly (P < 0.01) with increasing CP levels. Supplementing diets with phytase increased the AID of Ca (P < 0.01), P (P < 0.001), CP (P = 0.07), and the AA (P < 0.10) Gly, Ala, Val, Ile, Thr, TSAA, Asp, Glu, Phe, Lys, and Arg. Protein and phytase response equations were generated for those AA affected (P < 0.10) by both CP level and phytase supplementation. Based on these equations, 500 U/kg of phytase can replace 0.52 percentage units of the dietary CP, which includes a 0.03 percentage unit improvement in Lys AID. The results of this study show that supplementing pig diets with microbial phytase improves CP and AA digestibilities in addition to Ca and P digestibilities.

Technical Note: Improved technique for fitting pigs with steered ileocecal valve cannulas1,2

Collection of ileal digesta to evaluate AA digestibilities has become increasingly important in swine nutrition research. Steered ileocecal valve cannulation of pigs permits total collection of ileal digesta, while still allowing normal digesta flow during noncollection periods. This technique was modified and used with 64 crossbred barrows in five trials. Our procedural changes included preoperative i.v. administration of a broad-spectrum antibiotic and nonsteroidal antiinflammatory drug, sharp incision through the muscle layers of the laparotomy wound, use of a heparinized saline lavage solution, replacement of the guide ring with a stylette, and fixing the outer cannula barrel in place with a hose clamp. The current technique involves a right flank laparotomy, parallel and distal to the last rib, with the pig under general anesthesia. A stainless-steel ring (inner ring = 2.0 mm thick, 35.0 mm i.d.) is introduced into the ileal lumen through an enterotomy proximal to the origin of the ileocecal fold. A nylon string attached to this ring is threaded through the ileum and ileocecal valve into the cecum using a silastic stylette, which encases the string. A second stainless-steel ring (outer ring = 2.0 mm thick, 34 mm o.d.) is fixed in place around the ileum, distal to the inner ring and just proximal to the ileocecal valve. A polyurethane cannula barrel (barrel = 100 mm long, 26 mm i.d., 32 mm o.d.; flange = 70 mm o.d.) is introduced into the cecal lumen via an enterotomy through the lateral cecal band and secured in place with two purse-string sutures. The cannula is exteriorized through an incision caudal and proximal to the intial laparotomy site, where it is plugged using a cylindrical stopper (26 mm o.d., 55 mm long) and held in place by a second cannula barrel (barrel = 43 mm length, 33 mm i.d., 41 mm o.d.; flange = 80 mm o.d.). Procedural changes decreased postsurgical complications, as evidenced by decreased seepage around the cannula and fewer and less severe adhesions noted at necropsy. Based on five trials, this technique is a reliable means of collecting ileal digesta for nutrient analyses.

Nutritional value of a corn containing a glutamate dehydrogenase gene for growing pigs1

Eight female PIC Line 42 pigs (initial BW = 47.5 +/- 1.8 kg) were used in a two-period switchback design (n = 4 per treatment per period) to evaluate the nutritional difference between a genetically modified corn and a similar nontransgenic corn. The genetically altered corn (gdhA+) contained a glutamate dehydrogenase gene isolated from Escherichia coli. The non-transgenic corn was the same variety lacking the transgenic cassette, grown at the same two locations. Pigs were surgically fitted with steered ileocecal valve cannulas for collection of ileal digesta. Diets were made up of primarily one of the two corn sources. Dietary AA profiles were adjusted using crystalline AA to match Illinois Ideal Protein Ratios. Pigs were limit-fed at 8% of metabolic body weight (BW0.75) in two equal feedings at 0600 and 1800 daily throughout the experiment. The study consisted of two 15-d periods. Each period consisted of a 7-d acclimation period, a 3-d total collection of feces and urine, two 12-h ileal collections, and a 3-d adjustment period between ileal collections to ensure adequate hydration. Crude protein, leucine, methionine, alanine, aspartic acid, glutamic acid, and tyrosine concentrations were greater (P < 0.05) in the gdhA+ corn than in the nontransgenic variety. The presence of the gene did not alter (P > 0.17) BW gain. Similarly, DM digestibility, fecal N excretion (grams per day), apparent total-tract N digestibility, N balance, net protein utilization, and N retained as percentages of absorbed were not affected (P > or = 0.32) by the gene modification. Apparent ileal AA digestibility values did not differ (P > 0.31) between the two dietary treatments. Results of this study suggest corn that contains the E coli. gene for glutamate dehydrogenase was nutritionally equivalent to the unaltered variety.

Comparison of phytase from genetically engineered Aspergillus and canola in weanling pig diets

Ninety-six crossbred pigs with an average weight of 9.0 kg were used in a 5-wk trial to compare the efficacy of genetically engineered Aspergillus ficuum phytase, expressed in Aspergillus niger (Natuphos) or in canola seed (Phytaseed), for enhancing the utilization of phytate P in corn-soybean meal-based diets fed to young pigs and to evaluate the safety of Phytaseed phytase. Three levels of the two sources of phytase (250, 500, or 2,500 U/kg of diet) were added to a corn-soybean meal basal diet containing .35% total P, .09% available P, and .50% Ca. There were six pens per treatment (one barrow and one gilt/pen), except that the diet without added phytase was fed to 12 pens of pigs. Pen feed consumption and BW were recorded weekly. During wk 5, pen fecal samples were collected for determination of apparent digestibilities of DM, Ca, and P. At the end of wk 5, all barrows were killed, and the 10th rib on both sides was removed for determination of shear force and energy. Thirty pigs (six from the diet without added phytase and the diets with 500 and 2,500 U/kg phytase from both sources) were randomly selected for gross necropsy and histologic evaluation of liver, kidney, and bone tissues. Both sources of phytase were equally effective in increasing (P < .05) daily gain, gain:feed, apparent digestibilities of DM, P, and Ca, and 10th rib measurements. Fecal P excretion was reduced with phytase addition. Feed intake was increased by phytase levels during wk 4 to 5. No significant abnormalities were seen in any of the 30 pigs necropsied. The fit of a nonlinear function revealed that most measurements were reaching a plateau at 2,500 U/kg phytase. In summary, based on performance, bone measurements, and digestibilities of P, Ca, and DM of young pigs, the efficiency of Phytaseed was similar to that of Natuphos for enhancing the utilization of phytate P in corn-soybean meal-based diets. General necropsy and histologic examination of tissues indicated no toxic effect of phytase.

Comparison of genetically engineered microbial and plant phytase for young broilers

This study was conducted to compare the efficacy of genetically engineered microbial (Natuphos) and plant (Phytaseed) phytase for enhancing the utilization of phytate P in corn-soybean meal-based diets fed to young broilers and to evaluate the safety of Phytaseed phytase. Three levels of each of the two sources of phytase (250, 500, and 2,500 U/kg of diet) were added to a corn-soybean meal basal diet containing 0.46% total P, 0.21% nonphytate P, and 0.92% Ca. There were eight cages per treatment (eight birds per cage for Weeks 2 to 3 and seven birds for Weeks 4 to 5), except for the basal diet without added phytase that had 16 cages. Cage BW and feed consumption were recorded weekly. During Week 5, cage excreta samples were collected for determination of apparent retention coefficients of DM, Ca, and P. At the end of Week 5, all birds were killed, and the left and right toes were removed for determination of toe ash weight and percentage. Forty birds (one per cage from the diet without added phytase and diets with 500 or 2,500 U phytase/kg from both sources) were randomly selected for gross necropsy and histologic evaluation of liver, kidney, and bone tissues. Addition of both sources of phytase resulted in similar increases (P < 0.05) of BW gain; feed intake; gain:feed; apparent retention of DM, P and Ca; and toe measurements. Phosphorus excretion decreased as phytase addition increased. No significant abnormalities were seen in any of the 40 broilers necropsied. Further, the fit of a nonlinear function revealed that most measurements reached a plateau at 2,500 U/kg. Based on performance, bone characteristics, and retention of P, Ca, and DM of young broilers, the efficacy of Phytaseed phytase was similar to that of Natuphos phytase for enhancing the utilization of phytate P in corn-soybean meal-based diets. General necropsy and histologic examination of liver, kidney, and tibial tissues revealed no adverse effects of phytase source or level.

The effects of microbial phytase, citric acid, and their interaction in a corn-soybean meal-based diet for weanling pigs

Crossbred weanling pigs (an equal number of barrows and gilts) with an average initial weight of 7.4 (Exp. 1) or 9.6 kg (Exp. 2) were used in two 4-wk experiments (Exp. 1, n = 96; Exp. 2, n = 96) to investigate the effects of added phytase or citric acid on performance, rib mineralization, gastric pH, and digestibility measurements. A corn-soybean meal-based diet low in Ca and P was used in both experiments. In Exp. 1, three citric acid levels (0, 1.5, or 3.0%) and four phytase levels (0, 250, 500, or 750 U/kg) were used in a 3 x 4 factorial arrangement of treatments. In Exp. 2, two citric acid levels (0 or 2.0%) and three phytase levels (0, 250, or 500 U/kg) were used in a 2 x 3 factorial arrangement of treatments. Phosphorus was maintained at .33 and .34% in Exp. 1 and 2, respectively. Calcium was maintained at a 2.5:1 ratio with total available P (available P plus the estimated released phytate P by phytase) in Exp. 1 and at a level of .44% in Exp. 2. In both experiments, BW and feed consumption were measured weekly, and pen fecal samples were collected twice daily for 5 d during wk 4. At the end of wk 4, the barrow in each pen was killed following a fast-refeed-fast (22-1-2 h) regimen for collection of 10th ribs and stomach digesta. In Exp. 1 and 2, phytase addition did not affect (P > .05) performance but linearly increased (P < .05) rib shear force, shear energy, dry bone weight, ash weight, ash percentage, and Ca and P digestibilities. Addition of citric acid in both experiments reduced dietary pH and stomach digesta pH (P < .05). The addition of citric acid improved (P < .05) ADG, feed efficiency, and Ca digestibility in Exp. 1, but it had no effect on performance and Ca digestibility in Exp. 2. In summary, the additions of citric acid and phytase to weanling pig diets were each beneficial, but no synergistic effects were observed.

Factors affecting phosphorus and calcium digestibility in diets for growing-finishing pigs

In two experiments, we investigated various factors that affect the estimation of the apparent total tract digestibility (ATTD) of DM, Ca, and total P in diets for growing-finishing pigs. In Exp. 1, the effects of age, housing, and calculation method (indicator [Cr2O3] vs 10-d total collection) were determined. Eighteen barrows and gilts (40 to 95 kg BW) were housed in six pens, and ATTD was estimated using the indicator method. Twelve barrows were housed in metabolic crates, and ATTD was estimated using both calculation methods. Dietary treatments were 1) a tapioca-soybean-barley-based diet, 2) Diet 1 supplemented with 400 FTU microbial phytase/kg of diet, and 3) a corn-soybean meal-based diet: In Exp. 2, six barrows (95 to 120 kg BW) were fed a phytase-deficient diet to investigate the effects of coprophagy (40 g fresh feces/kg of diet) and movement. Pigs were fed at 2.8 times maintenance requirement (418 kJ ME/BW.75); water supply was 2.5 L/kg of feed. The ATTD increased as BW increased. Phytase enhanced total P ATTD by an average of 18.1 percentage units. The ATTD of DM was higher and the ATTD of Ca and total P (P < .001) were lower in pigs housed in pens than in pigs housed in metabolic crates. Fecal consumption and movement led to numerical increases in Ca (P = .217) and total P (P = .103) ATTD. Estimates of Ca and total P ATTD using pigs in metabolic crates are lower than estimates in practice.

The effects of sow parity on digestibility of proximate components and minerals during lactation as influenced by diet and microbial phytase supplementation

Ninety-six (Finnish Landrace x Dutch Landrace) reproductive sows were used at parities 1, 3, 5, and 7 + 8 from d 107 of gestation to d 21 of lactation to investigate the effects of diet and parity on apparent total tract digestibility (ATTD). Animals were randomly assigned to one of four dietary treatments. Dietary treatments were 1) a P-deficient (1.1 g digestible P [dP]/kg) Dutch semipractical diet; 2) Diet 1 supplemented with 400 FTU Aspergillus niger phytase per kilogram of diet (1.7 g dP/kg); 3) a corn-soybean meal-based diet (1.3 g dP/kg); and 4) Diet 3 supplemented with extra monocalcium phosphate (MCP; 2.4 g dP/kg of diet). Animals were fed twice daily at 2.8 times maintenance (418 kJ ME/ BW75) from d 8 to the end of lactation. Feces and urine were collected during d 11 to 13 and d 18 to 20 of lactation. The ATTD of DM, OM, ash, CP, Ca, Mg, and total P (P < .01) were higher for the corn-soybean meal-based diets than for the Dutch semipractical diet not supplemented with phytase. Addition of MCP enhanced total P ATTD by an average of 6.7 percentage units. Addition of microbial phytase improved Ca, Mg, and total P ATTD, but the effects were dependent on the stage of lactation. Lower ATTD of OM and CP were seen for first parity animals compared with higher parity sows. The ATTD of Mg increased with increasing parity. Parity had little effect on the ATTD of minerals during lactation, and dietary effects were prominent and followed a similar trend to those seen in growing-finishing pigs.