Effect of extrusion on energy and nutrient digestibility of lentil-based diets containing either supplemental plant or animal protein fed to growing pigs

Non-food grade and excess lentil grain production may be included in swine feeds to provide starch and protein and reduce feed cost. Extrusion processing may increase energy and nutrient digestibility of lentil-based diets containing either supplemental plant or animal protein sources. Therefore, the apparent ileal digestibility (AID) of crude protein (CP) and amino acids (AA), apparent total tract digestibility (ATTD) of gross energy (GE), and digestible energy (DE) value of lentil-based diets were assessed in growing pigs. Two diets were formulated to provide 2.4 Mcal net energy (NE)/kg and 4.35 g standardized ileal digestible lysine/Mcal NE: (1) soybean meal (SBM) diet, containing 50% lentil, 31% wheat, and 12.8% SBM; and (2) fish meal (FM) diet, containing 40% lentil, 45% wheat, and 10% FM. Following mixing, each diet batch was divided into two parts: one part remained as mash, whereas the other part was extruded using a single-screw extruder (400 rpm, 250 kg/h). Eight ileal-cannulated barrows (32.3 ± 1.5 kg) were fed the four diets at 2.8 times maintenance DE requirement (110 kcal per kg of body weight0.75) for four 9-d periods in a double 4 × 4 Latin square to achieve 8 observations per diet. Data were analyzed as a 2 × 2 factorial arrangement including protein source, post-mixing processing, and their interaction as fixed effects. The lentil sample contained 32.3% starch, 24.4% CP, 9.3% total dietary fiber, and 1.7 mg/g of trypsin inhibitor activity on as is-basis. Interactions between dietary protein source and post-mixing processing were not observed. Feeding FM diets resulted in greater (P < 0.05) AID of dry matter (DM), GE, and most AA, and ATTD of CP, but lower apparent hindgut fermentation of DM and GE than SBM diets. Extrusion increased (P < 0.05) the ATTD of GE and DE value of diets. The AID of CP and AA was 3.2 and 4.7%-units greater (P < 0.05), respectively, for the extruded than mash diets. In conclusion, feeding FM diets resulted in greater ileal digestibility of DM, GE, and AA than SBM diets. Extrusion increased the AID of CP and most AA, and DE value of lentil-based diets containing either supplemental plant protein or animal-protein, indicating that extrusion can increase the energy and protein value of plant-based diets fed to pigs.

Review: The amazing gain-to-feed ratio of newly weaned piglets: sign of efficiency or deficiency?

Shortly after weaning, piglets generally eat dry feed poorly; but nevertheless, a phenomenal gain-to-feed ratio is achieved as they gain about as much weight as they eat (150-200 g/d). The high gain-to-feed ratio, though, cannot be explained by their nutrient intake or nutrient repartitioning. Analyses based on tissue composition and bio-electrical impedance data showed that newly weaned piglets lose fat, maintain protein, and gain large amounts of water because of edema. This edema, which may well contribute up to one kg of BW, seems to be triggered by refeeding syndrome. Refeeding syndrome in adult humans occurs when subjects fast for an extended period of time (weeks) that results in downshifts in metabolic activity and concomitant shedding of phosphate (PO4), magnesium (Mg), and potassium (K) in urine. If food is abruptly reintroduced, thus, resulting in strong insulin spikes, metabolism is triggered but hampered by a lack of PO4, Mg, K, and thiamine, causing hypophosphatemia, metabolic stress, and edema. In piglets, the same process appears to happen immediately after weaning but in hours rather than weeks, possibly linked to their high metabolic rate. Refeeding syndrome can be lethal in humans but does not appear to be directly lethal in piglets. Our attempts to prevent it through altered diet composition and/or controlled feeding programs have not resulted in better performance at the end of the nursery phase. A practical ramification of weaning-induced edema is that growth and gain-to-feed ratio data immediately after weaning should be interpreted with caution. In addition, diets arguably should be formulated to not strongly trigger insulin release, while high lysine levels are not needed as the gain is not based on protein accretion.

Effect of increasing dietary fermentable fiber on diet nutrient digestibility and estimation of endogenous phosphorus losses in growing pigs

Fermentable fiber may increase endogenous losses of phosphorus (EPL) and amino acids (AA), thereby reducing apparent nutrient digestibility. Acacia gum with medium-to-high fermentability and low viscosity was increasingly included in diets to investigate its effect on apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients, gross energy (GE), and standardized total tract digestibility (STTD) of P in growing pigs. A control diet (49% cornstarch; 18% bovine plasma protein) was formulated to measure basal EPL. Three additional diets were formulated to include 2.5%, 5.0%, or 7.5% acacia gum at the expense of cornstarch. Diets contained 16.1% to 17.4% CP and 0.31% to 0.33% total P (DM-basis). The four diets were fed to eight ileal-cannulated barrows (initial BW, 54.6 kg) for four 9 d periods in a double 4 × 4 Latin square. Apparent hindgut fermentation (AHF) was calculated as ATTD minus AID. Feeding increasing acacia gum quadratically affected (P < 0.05) AID of DM, GE, linearly decreased (P < 0.05) ATTD of DM, crude protein (CP), GE, digestible (DE) and predicted net energy (NE) value of diets, and linearly increased (P < 0.001) AHF of DM and GE. Increasing acacia gum did not affect AID and standardized ileal digestibility (SID) of CP and AA. Basal EPL was 377 mg/kg DM intake (DMI) and increasing acacia gum linearly increased (P < 0.05) total tract EPL. Increasing acacia gum linearly decreased (P < 0.05) diet ATTD of P, and STTD of P based on either the calculated EPL or NRC (2012) recommended value (190 mg P/kg DMI). Increasing acacia gum did not affect AID and ATTD of Ca of diets. In conclusion, feeding increasing dietary fermentable, low-viscous acacia gum decreased diet AID and ATTD of DM and GE, but did not affect AID or SID of CP and AA. Increasing acacia gum decreased ATTD of P, which might have been due to increased specific endogenous losses of P in the total tract of growing pigs.

Dietary benzoic acid and supplemental enzymes alter fiber-fermenting taxa and metabolites in the cecum of weaned pigs

Inclusion of enzymes and organic acids in pig diets is an important strategy supporting decreased antibiotic usage in pork production. However, limited knowledge exists about how these additives impact intestinal microbes and their metabolites. To examine the effects of benzoic acid and enzymes on gut microbiota and metabolome, 160 pigs were assigned to one of four diets 7 days after weaning: a control diet or the addition of 0.5% benzoic acid, 0.045% dietary enzymes (phytase, β-glucanase, xylanase, and α-amylase), or both and fed ad libitum for 21 to 22 d. Individual growth performance and group diarrhea incidence data were collected throughout the experimental period. A decrease of 20% in pen-level diarrhea incidence from days 8 to 14 in pigs-fed both benzoic acid and enzymes compared to the control diet (P = 0.047). Cecal digesta samples were collected at the end of the experimental period from 40 piglets (n = 10 per group) and evaluated for differences using 16S rRNA sequencing and two-dimensional gas chromatography and time-of-flight mass spectrometry (GCxGC-TOFMS). Analysis of cecal microbiota diversity revealed that benzoic acid altered microbiota composition (Unweighted Unifrac, P = 0.047, r2 = 0.07) and decreased α-diversity (Shannon, P = 0.041; Faith's Phylogenetic Diversity, P = 0.041). Dietary enzymes increased fiber-fermenting bacterial taxa such as Prevotellaceae. Two-step feature selection identified 17 cecal metabolites that differed among diets, including increased microbial cross-feeding product 1,2-propanediol in pigs-fed benzoic acid-containing diets. In conclusion, dietary benzoic acid and enzymes affected the gut microbiota and metabolome of weaned pigs and may support the health and resolution of postweaning diarrhea.

168 Evaluation and Improvement of the Nutritional Value of Cereal and Pulse Grains for Swine

Feed represents the greatest variable cost of swine production, with feed energy as its largest component. In most swine production systems, cereal grains such as corn, wheat, or barley provide historically the most energy in feed. Cereal grains contain &gt;50% starch and &lt; 20% crude protein. Pulse grains such as field pea, faba bean, and chick pea are now widely grown on the Great Plains for human consumption and crop diversification. Pulse grains contain 30 to 40% starch and 20 to 30% crude protein. Apparent total tract digestibility (ATTD) of starch does not differ between cereal and pulse grain. However, apparent ileal digestibility (AID) of starch is lower for pulse grains; thus, apparent hindgut fermentation of starch is greater. Both AID and ATTD of total dietary fiber are greater for pulse than cereal grains. Calculated net energy (NE) value is greater for cereal than pulse grains. Standardized ileal digestibility (SID) of lysine is greater for pulse than cereal grains. Cereal and pulse grains are milled prior to diet mixing, and particle size reduction can increase ATTD of energy. Whereas steam pelleting may not increase nutrient digestibility of pulse grains, extrusion may increase digestibility of both energy and amino acids. Fiber-degrading enzymes can increase nutrient digestibility of grains by depolymerizing the fiber matrix. In phase-3 nursery diets that are formulated to equal NE value and SID lysine, barley grain can replace wheat grain without reducing growth. Similarly, pulse grains can replace part of cereal grain and soybean meal in phase-3 nursery diets without reducing growth. In conclusion, pulse grains are alternative energy sources to cereal grains but can also replace protein feedstuffs such as soybean meal in sustainable swine feeding programs and provide agronomic benefits like rhizobia N fixation and reduced carbon footprint.

169 Evaluation and Improvement of the Nutritional Value of co-Products for Swine

Feed accounts for the greatest portion of swine production costs, and feed cost has been increasing during the last decades due to increased competition of feed ingredients with the food and biofuel industry. Exposure to climate change is also expected to impact feed cost by changing growing conditions, and recent supply chain disruptions undermine the pricing structure for imported feedstuffs. Therefore, the need for alternative feed ingredients to ensure the economic sustainability of the swine industry cannot be overstated. To this end, utilization of co-products from the agri-processing of cereals and oilseed crops has the potential to help mitigate feed cost and to reduce the environmental footprint of pork production. In general, however, co-products of the agri-processing industry tend to be more variable in their nutrient composition and content of such anti-nutritional factors as non-starch polysaccharides, phytate, and trypsin inhibitors. For these reasons, it is critical that co-products are characterized for the nutritional value and means to enhance their nutritive value examined. We have evaluated a wide range of co-products, including canola meal, camelina meal, hemp meal, extruded soybean meal, wheat co-products, flaxseed meal, etc., and means of enhancing their nutritive values. Examined approaches to ameliorate the negative impact of anti-nutritional factors and optimize energy and nutrient availability in these co-products include: exogenous enzymes supplementation to increase nutrient digestibility, heat treatments to reduce anti-nutritional factors, and particle size reduction to increase nutrient availability. Results of many of our studies clearly demonstrate that the nutritive value of these co-products for swine can be improved significantly through the application of these approaches, thus, offering opportunities to ensure sustainable swine production systems.

240 Nutritional Intervention to Improve Carbohydrate Utilization and gut Health in Pigs

In swine production, using feed antibiotics as antimicrobial growth promotants has been reduced; thus, feed alternatives to manage gut health are required. Dietary fiber, resistant starch, oligosaccharides, and exopolysaccharides are carbohydrate structures and are nutritional tools that may enhance gut health in pigs. Dietary carbohydrates may have a role to alleviate diarrheal diseases including in pigs post-weaning but also reduce constipation in sows. Antibiotics are hypothesized to influence gut health via modulation of intestinal microbial profiles; fermentation and intestinal inflammation are considered important mechanisms. Dietary fiber sources differ in 2 key properties: fermentability and solubility. Rapid fermentation of fiber and oligosaccharides is associated with changes in microbial profiles and increased metabolite production. Recently, microbial composition was hypothesized to be less important and combined output of metabolites should be the focus. Fiber properties may also manipulate retention time and physico-chemical properties of the undigested residue; hence, non-fermentable insoluble fiber may prevent constipation in sows. Starch is mostly digested and absorbed as glucose. However, resistant starch is not digested and acts as insoluble but fermentable fiber and has unique properties, because it specifically increases intestinal abundance of bifidobacteria, which are associated with improved gut health. Using crop breeding, feed processing, and feed additives, the structure of fiber and starch can be altered thereby changing its degradation kinetics and affecting its utilization as energy source and its prebiotic activity. Finally, exopolysaccharides from Limosilactobacillus reuteri and unique oligosaccharides may serve as receptor analogues for pathogenic bacteria, e.g., enterotoxigenic Escherichia coli (ETEC). These receptor analogues block lectin domains of bacterial adhesins and thus prevent adherence of pathogens to the gut wall, thereby avoiding initiation of post-weaning diarrhea. In conclusion, dietary carbohydrates are important energy sources but may also provide important solutions to maintain gut health in pigs.

Effect of Fiber Fermentation and Protein Digestion Kinetics on Mineral Digestion in Pigs

Nutrient kinetic data and the timing of nutrient release along the gastrointestinal tract (GIT), are not yet widely used in current feed formulations for pigs and poultry. The present review focuses on interactions between fermentable substrates (e.g., starch, fiber, and protein) and selected minerals on nutrient digestion and absorption to determine nutritional solutions to maximize animal performance, principally in the grower–finisher phase, with the aim of minimizing environmental pollution. For phosphorus (P), myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP6), copper (Cu), and zinc (Zn), no standardized methodologies to assess in vitro mineral digestion exist. The stepwise degradation of InsP6 to lower inositol phosphate (InsP) forms in the GIT is rare, and inositol phosphate4 (InsP4) might be the limiting isomer of InsP degradation in diets with exogenous phytase. Furthermore, dietary coefficients of standardized total tract digestibility (CSTTD) of P might be underestimated in diets with fermentable ingredients because of increased diet-specific endogenous P losses (EPL), and further clarification is required to better calculate the coefficients of true total tract digestibility (CTTTD) of P. The quantification of fiber type, composition of fiber fractions, their influence on digestion kinetics, effects on digesta pH, and nutrient solubility related to fermentation should be considered for formulating diets. In conclusion, applications of nutrient kinetic data should be considered to help enhance nutrient digestion and absorption in the GIT, thereby reducing nutrient excretion.

Cereal grain fiber composition modifies phosphorus digestibility in grower pigs

Increased fermentable carbohydrates (e.g., β-glucan, amylose) may increase endogenous losses including for P, and thereby reduce apparent total tract digestibility (ATTD) of P. The present study assessed effects of barley cultivars varying in fermentable starch and fiber on apparent ileal digestibility (AID) and ATTD of P, myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate; InsP6) and Ca, and standardized total tract digestibility (STTD) of P and the presence of lower inositol phosphates (InsP) compared to wheat. In a 6 (period) × 5 (diet) Youden square, 7 ileal-cannulated barrows (initial BW, 27.7 kg) were fed diets containing 80% of 1 of 5 cereal grains differing in amylose, β-glucan, and fiber content: 1) high-fermentable, high-β-glucan, hull-less barley (HFB); 2) high-fermentable, high-amylose, hull-less barley (HFA); 3) moderate-fermentable, hull-less barley (MFB); 4) low-fermentable, hulled barley (LFB); and 5) low-fermentable, hard red spring wheat (LFW). On dry matter (DM) basis, cereal grains contained between 0.32 to 0.53% total P and 0.24 to 0.50% InsP6-P. The InsP6-2-P was calculated as the sum of all detected InsP-P (InsP6-P to InsP2-P) in the sample. The P release of degraded InsP-P was calculated by using the following equation: sum InsP6-2-Pdiet (g/kg DM) × (AID or ATTD sum InsP6-2-P (%) / 100). Data were analyzed using a mixed model with diet as fixed effect, and pig and period as random effects. On DM basis, diets contained 41.4 to 50.6% starch, 0.88 to 8.54% β-glucan, 0.81 to 0.89% total P, and 0.19 to 0.35% InsP6-P. The MFB, LFB, and LFW had greater (P &lt; 0.05) diet AID of P than HFB and HFA, and MFB had greater (P &lt; 0.05) diet ATTD and STTD of P than HFB. The ATTD of InsP6-P was greater (P &lt; 0.05) for HFB than LFB and the ATTD of the sum InsP6-2-P was greater (P &lt; 0.05) for HFB and HFA than LFB. Total tract P release was greater (P &lt; 0.001) for HFB, HFA, and LFW than MFB and LFB. The LFW had greater (P &lt; 0.05) ATTD of Ca than LFB. Diet β-glucan content was not correlated with STTD of P (R 2 = 0.03) or ATTD of InsP6 (R 2 = 0.05). In conclusion, cereal grains high in fermentable fiber, e.g., amylose and β-glucans included in specific hull-less barley cultivars, had lower diet AID, ATTD, and STTD of P, but greater ATTD of InsP6-P and sum InsP6-2-P. Carbohydrate fermentation thus results in greater total tract P release from InsP-P hydrolysis.

Effect of feeding mid- or zero-tannin faba bean cultivars differing in vicine and covicine content on diet nutrient digestibility and growth performance of weaned pigs

To prioritize what cultivars to grow to feed pigs, 5 faba bean cultivars including 3 zero-tannin, high vicine and covicine cultivars (Snowbird, Snowdrop, Tabasco) and 2 medium-tannin, lower vicine and covicine cultivars (Fabelle, and Malik) were fed to compare effects on diet nutrient digestibility and growth performance of weaned pigs. A total of 260 pigs (8 ± 1.2 kg), weaned at 20 ± 1 d of age housed 2 barrows and 2 gilts/pen were fed 1 of 5 dietary regimens starting 1-week post-weaning for 4 weeks in a randomized complete block design. Diets including each cultivar at 20% or 30% provided 10.2 and 10.1 MJ net energy (NE)/kg and 1.3 and 1.2 g standardized ileal digestible (SID) lysine (Lys)/MJ NE in phase 1 and phase 2, respectively. Digestibility data were analyzed using PROC GLIMMIX and growth performance data were analyzed using PROC MIXED with pen as experimental unit. Fabelle contained the most condensed tannins (CT; 0.53%) but the least vicine (0.04%) and covicine (0.01%). Zero-tannin cultivars contained little CT (&lt; 0.2%) but had the greatest vicine (0.5%) and covicine content (0.4%). For phase 1, diet apparent total tract digestibility (ATTD) of dry mater (DM), gross energy (GE), crude protein (CP), digestible energy (DE), and NE values did not differ among cultivars. For phase 2, diet ATTD of DM and GE were greatest (P &lt; 0.05) for Snowdrop and Tabasco, intermediate for Fabelle, and lowest for Malik; Snowbird was not different from Fabelle or Malik. Diet ATTD of CP was greatest (P &lt; 0.05) for Tabasco, intermediate for Snowbird, and lowest for Malik; Snowdrop was not different from Tabasco or Snowbird, and Fabelle was not different from Snowbird or Malik. Diet DE and NE values were greatest (P &lt; 0.05) for Tabasco, intermediate for Fabelle and Snowdrop, and lowest for Snowbird; Malik was not different from Fabelle or Snowbird. For the entire trial (d 0 to 28), daily feed disappearance and weight gain for pigs fed Fabelle were 10% greater (P &lt; 0.05) than those fed Malik; pigs fed zero-tannin cultivar diets were intermediate. Pigs fed Fabelle were 1.6 kg heavier (P &lt; 0.05) than those fed Malik at the end of the trial; pigs fed zero-tannin cultivar diets were intermediate. In conclusion, growth performance of pigs fed faba bean cultivar diets was more related to feed disappearance than diet nutrient digestibility. Vicine and covicine instead of condensed tannin content of faba bean cultivars seemed more relevant to growth performance in weaned pigs.

29 Nutritional Interventions for Intestinal Health of Nursery Pigs: Carbohydrates

In swine production, using feed antibiotics as antimicrobial growth promotants has been reduced; thus, feed alternatives to manage gut health are required to prevent post-weaning diarrhea. Dietary fiber, resistant starch, oligosaccharides, and exopolysaccharides are carbohydrates that together with glycoproteins are nutritional tools that may be part of managing gut health in pigs. Antibiotics are hypothesized to influence gut health via modulation of intestinal microbial profiles; fermentation and intestinal inflammation are considered important mechanisms. Dietary fiber is an alternative, but its sources differ in at least 2 key properties: fermentability and viscosity. Rapid fermentation of fiber and oligosaccharides is associated with changes in microbial profiles and increased metabolite production. Recently, microbial composition was hypothesized to be less important and combined output of metabolites should be the focus. Increased viscosity has been associated with increased gut content of virulence factors that are linked with diarrhea. Fiber properties may also manipulate retention time and physico-chemical properties of the undigested residue. Starch is mostly digested and absorbed as glucose. However, resistant starch is not digested and acts as fermentable fiber but has unique properties, because it specifically increases intestinal abundance of bifidobacteria that are associated with improved gut health. Feed ingredients and some feed additives influence kinetics of fermentation and have prebiotic activity. Their kinetics of fermentation should be quantified so that it can be considered in feed formulation. Finally, exopolysaccharides from Limosilactobacillus reuteri and unique oligosaccharides and glycoprotein may serve as receptor analogues for pathogenic bacteria, e.g., enterotoxigenic Escherichia coli (ETEC). These receptor analogues block lectin domains of bacterial adhesins and thus prevent adherence of pathogens to the gut wall, thereby avoiding initiation of post-weaning diarrhea. In conclusion, dietary fiber and other carbohydrates may be important solutions to maintain gut health when antibiotics are removed as growth promotants from swine feeds.

Resistant starch: Implications of dietary inclusion on gut health and growth in pigs: a review

Starch from cereal grains, pulse grains, and tubers is a major energy substrate in swine rations constituting up to 55% of the diet. In pigs, starch digestion is initiated by salivary and then pancreatic α-amylase, and has as final step the digestion of disaccharides by the brush-border enzymes in the small intestine that produce monosaccharides (glucose) for absorption. Resistant starch (RS) is the proportion of starch that escapes the enzymatic digestion and absorption in the small intestine. The undigested starch reaches the distal small intestine and hindgut for microbial fermentation, which produces short-chain fatty acids (SCFA) for absorption. SCFA in turn, influence microbial ecology and gut health of pigs. These fermentative metabolites exert their benefits on gut health through promoting growth and proliferation of enterocytes, maintenance of intestinal integrity and thus immunity, and modulation of the microbial community in part by suppressing the growth of pathogenic bacteria while selectively enhancing beneficial microbes. Thus, RS has the potential to confer prebiotic effects and may contribute to the improvement of intestinal health in pigs during the post-weaning period. Despite these benefits to the well-being of pigs, RS has a contradictory effect due to lower energetic efficiency of fermented vs. digested starch absorption products. The varying amount and type of RS interact differently with the digestion process along the gastrointestinal tract affecting its energy efficiency and host physiological responses including feed intake, energy metabolism, and feed efficiency. Results of research indicate that the use of RS as prebiotic may improve gut health and thereby, reduce the incidence of post-weaning diarrhea (PWD) and associated mortality. This review summarizes our current knowledge on the effects of RS on microbial ecology, gut health and growth performance in pigs.

Hindgut fermentation of starch is greater for pulse grains than cereal grains in growing pigs

The nutritive value of starch, the major source of dietary energy in pigs, varies depending on its susceptibility for digestion. The botanical origin of starch determines starch structure, and therefore, digestibility. To compare digestibility of starch, fiber, gross energy (GE), crude protein, and amino acid (AA), and to characterize undigested starch of grains in growing pigs, seven ileal-cannulated barrows (initial body weight, 30 kg) were fed six diets containing 96% of one of six test ingredients (three pulse grains: zero-tannin faba bean, green field pea, or mixed-cultivar chickpea; three cereal grains: hulled barley, hard red spring wheat, or hybrid yellow, dent corn), or a N-free diet in a 7 × 7 Latin square at 2.8 × maintenance digestible energy. Grain samples were ground with a hammer mill through a 2.78-mm screen. Amylose content ranged from 29% to 34% for pulse grains and from 22% to 25% for cereal grains. The apparent ileal digestibility (AID) of starch was greater (P < 0.05) in cereal (94% to 97%) than pulse grains (85% to 90%) and was lowest (P < 0.05) in faba bean (85.3%) followed by field pea (87.2%) and chickpea (90.1%). However, apparent total tract digestibility (ATTD) of starch of all tested grains was close to 100%. Apparent hindgut fermentability (AHF, as ATTD - AID) of starch was greater (P < 0.05) in pulse grains (9.9% to 15%) than cereal grains (3.3% to 4.8%). The AHF of total dietary fiber tended to be the greatest (P < 0.10) for corn (43.5%) and lowest for wheat (25.3%). The AHF of GE was greater (P < 0.05) in pulse grains (17% to 20%) than in cereal grains (9% to 11%) and resulted in greater (P < 0.05) digestible energy (DE) contribution from hindgut fermentation for pulse grains than cereal grains (0.9 vs. 0.5 Mcal/kg). Wheat had the greatest standardized ileal digestibility of total AA (90.2%; P < 0.05). Confocal laser scanning microscopy images revealed that 20% to 30% of starch granules of pulse grains were entrapped in protein matrixes. In scanning electron microscopy images, starch granules were larger in faba bean and field pea than cereal grains. Digesta samples revealed pin holes and surface cracks in starch granules of corn and wheat, respectively. In conclusion, hindgut fermentation of starch and fiber was greater in pulse grains than cereal grains resulting in a greater DE value despite lower ileal DE for pulse grain than cereal grains. Defining the digestible and fermentable fractions of starch may enhance the accuracy of equations to predict the net energy value of these feedstuffs.

121 Use of Fermentation Co-products in Pet Food and Animal Feeds

Fermentation is used to create foods and beverages that are enjoyed by people around the world. Similarly, fermentation creates direct opportunities for feed application such as fermented liquid feed or fermented feedstuffs. Other opportunities exist: fermentation followed by extraction of a main product for human or biofuel application also creates co-products that require application in petfood or animal feeds for valorization. Indeed, cereal grains are fermented to produce beer, distilled spirits, or bioethanol and their associated co-products can be fed either wet or dry. For example, traditional beer production using fermentation of barley grain produces abundant brewer’s spent grains and also brewer’s spent hops and yeast as co-products. Brewer’s spent grains are mostly fed wet to ruminants due to its greater fiber content than barley grain and avoiding the cost of its drying required for compound feed application. Wet brewer’s yeast can be used as feedstuff in liquid feed systems for swine. Dried brewer’s yeast can be considered for pet food application due to included nutrients, nucleotides, mannan oligosaccharides, and β-glucans. Other cereal grains such as corn and rice are also used for beer production. Whiskey is produced using fermentation of an array of cereal grains, and distiller’s co-products have traditionally been fed wet or dry mostly to cattle. For the last two decades, large-scale production of ethanol as biofuel has created the co-product distillers dried grains with solubles (DDGS) as commodity feedstuff. Subsequently, DDGS has been used in livestock feed and petfood as protein source. With animal feed application, dietary inclusion of fermentation co-products provides opportunities for circular agriculture whereby nutrients excreted by livestock will be applied to soil to support grain production. Finally, depending on price and quality, fermentation co-products may be part of pet food and livestock feed formulations to achieve competitive cost and functionality.

Toward Precise Nutrient Value of Feed in Growing Pigs: Effect of Meal Size, Frequency and Dietary Fibre on Nutrient Utilisation

Simple Summary

Feed costs are the most important in swine production. Precise determination of nutritional values of pig diets can help reducing feed costs by reducing security margins for nutrients and therefore provide a more sustainable swine production. In commercial farms, pigs have free access to feed and eat with no limitation according to their natural behaviour. In contrast, during digestibility trials, pigs are restricted in their daily intake of feed, which is distributed in a limited number of meals. The number of meals per day and the amount of feed consumed daily can affect the digestibility of the nutrients, the transit time and the metabolism. To reduce feed costs, by-products are frequently added to diets. Most by-products are rich in dietary fibre, which are known to have negative effects on digestibility. Enzymes can be supplemented in the diet to counteract the negative aspects of dietary fibre, but their efficiency can vary depending on the number of meals per day and the amount of feed consumed daily.

Abstract

Nutritional values of ingredients have been and still are the subject of many studies to reduce security margins of nutrients when formulating diets to reduce feed cost. In most studies, pigs are fed a limited amount of feed in a limited number of meals that do not represent how pigs are fed in commercial farm conditions. With free access to feed, pigs follow their intrinsic feeding behaviour. Feed intake is regulated by satiety and satiation signals. Reducing the feed intake level or feeding frequency can affect digestibility and transit time and induce metabolic changes. To reduce feed costs, alternative ingredients that are frequently rich in dietary fibre are added to diets. Fibre acts on the digestion process and transit time by decreasing energy density and causing viscosity. Various analyses of fibre can be realised, and the measured fibre fraction can vary. Exogenous enzymes can be added to counteract the effect of fibre, but digestive tract conditions, influenced by meal size and frequency, can affect the efficiency of supplemented enzymes. In conclusion, the frequency and size of the meals can affect the digestibility of nutrients by modulating gastrointestinal tract conditions (pH and transit time), metabolites (glucose and short-chain fatty acids) and hormones (glucagon-like peptide 1 and peptide tyrosine tyrosine).

Net energy value of canola meal, field pea, and wheat millrun fed to growing-finishing pigs

Two experiments were conducted to (1) determine net energy (NE) values of soybean meal (SBM), Napus canola meal (NCM), Juncea canola meal (JCM), field pea, and wheat millrun (WM) using indirect calorimetry, and (2) compare the determined NE values with the calculated NE values of the same feedstuffs based on a prediction equation. In experiment 1, six ileal-cannulated barrows (31 kg) were fed five diets in 5 × 6 Youden square to give six replicates per diet. Diets were cornstarch-based diets containing SBM, NCM, JCM, field pea, or WM. The SBM was included as a reference. In experiment 2, six ileal-cannulated barrows (70 kg) were fed a N-free diet for determining energy digestibility and NE values of test feedstuffs fed in experiment 1 by difference method. The NE values of test feedstuffs were also calculated from the digestible energy (DE) values and analyzed macronutrient content of the test feedstuffs. On dry matter (DM) basis, SBM, NCM, JCM, field pea, and WM contained 51%, 41%, 42%, 28%, and 18% crude protein; 1.52%, 2.95%, 2.36%, 1.33%, and 3.12% ether extract; 2.93%, 0.14%, 1.44%, 36.7%, and 28.7% starch; and 5.30%, 21.0%, 13.4%, 9.49%, and 16.1% acid detergent fiber, respectively. The determined NE value for SBM (2.29 Mcal/kg) did not differ from that of NCM (1.72 Mcal/kg DM) or JCM (2.14 Mcal/kg DM). The NCM and JCM did not differ in NE value. Also, the determined NE value did not differ between field pea (2.00 Mcal/kg) and WM (2.55 Mcal/kg). The calculated NE values for SBM (2.18 Mcal/kg DM), NCM (1.73 Mcal/kg DM), and JCM (1.86 Mcal/kg DM) did not differ from the corresponding determined NE values of the same feedstuffs. However, the calculated NE value for field pea (2.51 Mcal/kg DM) was greater (P = 0.004) than the determined NE value of field pea, whereas the calculated NE value for WM (2.27 Mcal/kg DM) tended to be lower (P = 0.054) than the determined NE value of WM. In conclusion, the NE value for SBM and canola meals can be predicted based on the DE value and the macronutrient composition of the same feedstuffs. However, the NE value for field pea and WM may not be predicted precisely based on the DE value and the macronutrient composition of the same feedstuffs.

Effect of feeding acidified or fermented barley using Limosilactobacillus reuteri with or without supplemental phytase on diet nutrient digestibility in growing pigs

Fermentation of cereal grains may degrade myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP6) thereby increasing nutrient digestibility. Effects of chemical acidification or fermentation with Limosilactobacillus (L.) reuteri with or without phytase of high β-glucan hull-less barley grain on apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients and gross energy (GE), standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AAs), and standardized total tract digestibility (STTD) of P were assessed in growing pigs. Pigs were fed four mash barley-based diets balanced for water content: 1) unfermented barley (Control); 2) chemically acidified barley (ACD) with lactic acid and acidic acid (0.019 L/kg barley grain at a ratio of 4:1 [vol/vol]); 3) barley fermented with L. reuteri TMW 1.656 (Fermented without phytase); and 4) barley fermented with L. reuteri TMW 1.656 and phytase (Fermented with phytase; 500 FYT/kg barley grain). The acidification and fermentation treatments occurred for 24 h at 37 °C in a water bath. The four diets were fed to eight ileal-cannulated barrows (initial body weight [BW], 17.4 kg) for four 11-d periods in a double 4 × 4 Latin square. Barley grain InsP6 content of Control, ACD, Fermented without phytase, or Fermented with phytase was 1.12%, 0.59%, 0.52% dry matter (DM), or not detectable, respectively. Diet ATTD of DM, CP, Ca, and GE, digestible energy (DE), predicted net energy (NE) value, and urinary excretion of P were greater (P < 0.05) for ACD than Control. Diet ATTD of DM, CP, Ca, GE, DE and predicted NE value, urinary excretion of P was greater (P < 0.05), and diet AID of Ca and ATTD and STTD of P tended to be greater (P < 0.10) for Fermented without phytase than Control. Diet ATTD of GE was lower (P < 0.05) and diet ATTD and STTD of P, AID and ATTD of Ca was greater (P < 0.05) for Fermented with phytase than Fermented without phytase. Acidification or fermentation with/without phytase did not affect diet SID of CP and AA. In conclusion, ACD or Fermented without phytase partially degraded InsP6 in barley grain and increased diet ATTD of DM, CP, and GE, but not SID of CP and most AA in growing pigs. Fermentation with phytase entirely degraded InsP6 in barley grain and maximized P and Ca digestibility, thereby reducing the need to provide inorganic dietary P to meet P requirements of growing pigs.

PSIII-17 Extrusion Enhances Nutrient and Energy Digestibility of Pulse Grain-based Diets Fed to Growing Pigs

Heat processing may enhance nutrient digestibility of diets based on pulse grains. The objective of this study was to determine nutrient and energy digestibility of extruded lentil-based diets containing either supplemental plant or animal protein source in growing pigs. Two diets were formulated to provide 2.4 Mcal NE/kg and 4.35 g standardized ileal digestible Lys/Mcal NE: 1) soybean meal diet (SBM), containing 50% lentil, 31% wheat, and 12.8% soybean meal; and 2) fish meal diet (FM), containing 40% lentil, 45% wheat, and 10% fish meal. Following mixing, each diet was divided into 2 parts: one part remained mash while the other part was extruded using a single-screw extruder (105°C, 400 rpm, 5 kg water/h). The 2 extruded and 2 non-extruded diets were tested in a 2 × 2 factorial arrangement. Eight ileal-cannulated barrows (32.3 kg) were fed the 4 diets at 2.8 times maintenance DE (110 kcal per kg of BW0.75) for four 9-d periods in a double 4 × 4 Latin square. The FM diets had greater (P &lt; 0.05) AID of DM, GE, and most AA, and ATTD of CP, but lower apparent hindgut fermentation of DM and GE than the SBM diets. The AID of CP and AA were 3.2 and 4.7%-units greater (P &lt; 0.05), respectively, and the ATTD of GE and DE values were 2.1 and 3.1%-units greater (P &lt; 0.05), respectively, for the extruded diets than the non-extruded diets. Interactions between protein source and extrusion were not observed. In conclusion, FM diets had greater ileal digestibility of DM, energy, and AA than SBM diets. Extrusion increased the AID of CP and most AA, and DE value of both plant- and animal-protein diets based on lentil grain, indicating that extrusion can increase the energy and protein value of pulse-grain based diets fed to growing pigs.

PSIII-16 Growth Performance of Weaned Pigs Fed Barley Differing in Fermentable Starch and Fiber Profile

Barley grain containing more fermentable starch or fiber might be an attractive energy source in weaned pig diets due to benefits on gut health. Barley rapidly-fermentable carbohydrates may serve as prebiotic and slowly-fermentable fiber may decrease diarrhea in weaned pigs. Steam-explosion processing may disrupt the fiber matrix of hulls, increasing slowly-fermentable fiber of barley. To explore, 220 pigs were fed 1 of 5 diets containing 60% cereal grain: 1) low-fermentable hulled barley (LFB); 2) LFB steam-exploded (LFB-E; 1.2 MPa, 120 s); 3) high β-glucan (10% DM) hull-less barley (HFB); 4) high amylose (17% DM) hull-less barley (HFA); or 5) low-fermentable wheat (LFW). Diets were fed starting 1-week post-weaning and formulated to provide 2.4 and 2.3 Mcal net energy (NE)/kg, 5.5 and 5.1 g standardized ileal digestible lysine/Mcal NE for phase 1 (day 1–14) and phase 2 (day 15–35), respectively. For the entire trial (day 1–35), average daily feed intake (ADFI) and average daily gain (ADG) of pigs did not differ among diets. Gain:feed (G:F) did not differ between LFB and LFW diets, but steam-explosion of hulled barley reduced (P &lt; 0.05) G:F. Feces consistency did not differ between LFB and LFW diets, but was better (P &lt; 0.05) for LFB than HFB, HFA and LFB-E diets. For phase 1, G:F of pigs was lower (P &lt; 0.05) for LFB-E diet than LFW diet. For days 22–28, LFB-E diet had greater (P &lt; 0.01) ADFI than HFA diet and tended (P = 0.09) to have a greater ADG than HFB diet. In conclusion, hulled or hull-less barley grain replaced wheat grain without affecting growth performance in weaned pigs. Hulled barley increased feces consistency. Steam-explosion of hulled barley did not increase growth performance of weaned pigs. Barley grain is an attractive energy source for weaned pigs for managing growth and feces consistency.

Nutrient digestibility of extruded canola meal in ileal-cannulated growing pigs and effects of its feeding on diet nutrient digestibility and growth performance in weaned pigs

Canola meal (CM) contains less crude protein (CP) and more fiber and anti-nutritional factors such as glucosinolates than soybean meal (SBM) and consequently has a lower nutrient digestibility. Therefore, processing strategies that may increase the feeding value of CM warrant study. In two experiments, the effects of extrusion of Brassica napus CM on apparent (AID) and standardized ileal digestibility (SID) of amino acids (AA), apparent total tract digestibility (ATTD) of gross energy (GE) in growing pigs, and growth performance and diet digestibility in weaned pigs were assessed. Solvent-extracted CM was extruded using a single-screw extruder at three screw speeds: 250 (CM-250), 350 (CM-350), or 450 (CM-450) rpm. In exp. 1, in a double 4 × 4 Latin square, eight ileal-cannulated barrows (initial body weight [BW], 68.1 kg) were fed corn starch-based diets containing 50% CM or extruded CM. The CM sample contained 43.2% CP, 33.2% total dietary fiber (TDF), and 8.9 µmol of total glucosinolates/g on a dry matter (DM) basis. Extrusion increased (P < 0.05) the AID of CP, reduced (P < 0.05) apparent hindgut fermentation of CP, and decreased (P < 0.05) predicted net energy (NE) value of diets. Extrusion increased diet AID and CM SID of most indispensable AA by 3.1 to 5.3%-units. In exp. 2, 200 weaned pigs (initial BW, 8.3 kg) were fed diets containing 20% SBM, CM, or extruded CM starting 2 wk postweaning for 3 wk. The CM sample contained 42.7% CP, 28.3% TDF, and 5.3 µmol total glucosinolates/g DM. Wheat-based diets provided 2.3 Mcal NE/kg and 5.1 g SID Lys/Mcal NE. Dietary inclusion of extruded CM replacing SBM decreased (P < 0.05) diet ATTD of DM, GE and CP, and DE value. Average daily feed intake, average daily gain (ADG), and gain:feed (G:F) of pigs did not differ between extruded CM and SBM diets and were not affected by extrusion, but increasing extruder screw speed linearly increased (P < 0.05) ADG for day 1 to 7 and G:F for the entire trial. In conclusion, extrusion increased diet AID and CM SID of AA but not DE and predicted NE values of CM. However, increasing extruder speed did not further increase the SID of most of the AA of CM in growing pigs. Dietary inclusion of 20% CM or extruded CM did not affect the growth performance in weaned pigs.

Review of the beneficial and anti-nutritional qualities of phytic acid, and procedures for removing it from food products

Phytic acid (PA) is the primary phosphorus reserve in cereals and legumes which serves the biosynthesis needs of growing tissues during germination. It is generally considered to be an anti-nutritional factor found in grains because it can bind to minerals, proteins, and starch, limiting their bioavailability. However, this same mineral binding property can also confer a number of health benefits such as reducing the risk of certain cancers, supporting heart health, and managing renal stones. In addition, the ability of PA to bind minerals allows it to be used in certain food quality applications such as stabilizing the green color of vegetables, preventing lipid peroxidation, and reducing enzymatic browning in fruits/vegetables. These beneficial properties create a potential for added-value applications in the utilization of PA in many new areas. Many possible processing techniques for the preparation of raw materials in the food industry can be used to reduce the concentration of PA in foods to mitigate its anti-nutritional effects. In turn, the recovered PA by-products could be available for novel uses. In this review, a general overview of the beneficial and anti-nutritional effects of PA will be discussed and then dephytinization methods will be explained.

Feeding Limosilactobacillus fermentum K9-2 and Lacticaseibacillus casei K9-1, or Limosilactobacillus reuteri TMW1.656 Reduces Pathogen Load in Weanling Pigs

Applying probiotics to improve gut health and growth performance of pigs is considered an effective approach to reduce use of antimicrobial growth promoters in swine production. Understanding the properties of these probiotics is a prerequisite for the selection of probiotic strains for pigs. Host-adapted probiotic strains were suggested to exert probiotic effects by different mechanisms when compared to free-living or nomadic probiotic strains. This study assessed the effect of probiotic intervention with Limosilactobacillus reuteri TMW1.656, a host-adapted species producing the antimicrobial compound reutericyclin, its isogenic and reutericyclin-negative L. reuteri TMW1.656ΔrtcN, and with Limosilactobacillus fermentum and Lacticaseibacillus casei, two species with a nomadic lifestyle. Probiotic strains were supplemented to the post weaning diet in piglets by fermented feed or as freeze-dried cultures. The composition of fecal microbiota was determined by high throughput sequencing of 16S rRNA gene sequence tags; Enterotoxigenic Escherichia coli and Clostridium perfringens were quantified by qPCR targeting specific virulence factors. Inclusion of host-adapted L. reuteri effectively reduced ETEC abundance in swine intestine. In contrast, nomadic L. fermentum and L. casei did not show inhibitory effects on ETEC but reduced the abundance of Clostridium spp. In addition, the increasing abundance of Bacteriodetes after weaning was correlated to a reduction of ETEC abundance. Remarkably, the early colonization of piglets with ETEC was impacted by maternal-neonatal transmission; the pattern of virulence factors changed significantly over time after weaning. Probiotic intervention or the production of reutericyclin showed limited effect on the overall composition of commensal gut microbiota. In conclusion, the present study provided evidence that the lifestyle of lactobacilli is a relevant criterion for selection of probiotic cultures while the production of antimicrobial compounds has only minor effects.

261 Increasing dietary amylose reduces rate of starch digestion and increases microbial fermentation in weaned pigs

Beneficial effects of SCFA in modulating gut health stimulated interest on dietary strategies to increase intestinal microbial activity and digesta SCFA. Amylose has lower apparent ileal digestibility (AID) than amylopectin. In the large intestine, undigested starch is fermented by microbes producing SCFA. The objective was to determine effects of increasing dietary amylose on starch flow and metabolite profile along the intestinal tract in weaned pigs. Weaned pigs (n=32; initial BW, 8.4 kg) were randomly allocated to 4 diets containing 67% starch with 0, 20, 35, or 70% amylose in a randomized complete block design. On day 21, pigs were euthanized to collect digesta and feces for evaluating starch digestion and metabolite profiles. Apparent hindgut fermentation (AHF) was calculated as apparent total tract digestibility minus AID. Feed intake was 12% lower (P &lt; 0.05) and growth rate was 18% lower (P &lt; 0.05) for pigs fed 70% amylose than pigs fed 0, 20, or 35% amylose. Feed efficiency was greatest (P &lt; 0.05) for pigs fed with 35% amylose. The AID of starch was 44% lower (P &lt; 0.05) in pigs fed 70% amylose. Starch was completely digested by the proximal colon in pigs fed 0, 20, or 35% amylose, but AHF of starch was 14% greater (P &lt; 0.05) in pigs fed 70% amylose. Increasing dietary amylose did not alter digesta SCFA in the small intestine, but increased (P &lt; 0.05) digesta SCFA in the cecum, specifically acetate and total SCFA, and increased (P &lt; 0.05) propionate and valerate in all sections of the colon. In conclusion, increasing dietary amylose in weaned pigs stimulated hindgut fermentation of starch with a corresponding increase in digesta total SCFA in the cecum and colon. Optimizing dietary amylose may exert its effect as dietary prebiotic while promoting an optimal growth rate in young pigs.

133 Supplementing xylanase increased the digestibility of non-starch polysaccharides, particularly arabinoxylan, in diets high in insoluble corn fiber fed to swine with a 36-d dietary adaptation period

Xylanase should increase arabinoxylan digestibility in swine, but the responses in corn-based diets are inconsistent. The experimental objective was to investigate xylanase efficacy in growing pigs fed a diet high in insoluble corn fiber and afforded a longer adaptation period than typically reported in the literature. Sixty gilts (25.4 ± 0.9 kg BW; L337 × Camborough), were blocked by weight, housed individually, and randomly assigned to one of four dietary treatments: a low-fiber control [LF; 6.9% non-starch polysaccharides (NSP)], a 30% corn bran high-fiber control (HF; 17.6% NSP), HF + 100 mg xylanase/kg (HF+XY; Econase XT 25P; AB Vista, Marlborough, UK), and HF + 50 mg arabinoxylan-oligosaccharide/kg (HF+AX; 3-7 degrees of polymerization). Diets contained 0.5% CrO3. Gilts were fed ad libitum for 36 d, followed by 10-d of limit feeding (80% of average ad libitum intake) and were housed in metabolism crates. On d 46, pigs were necropsied and ileal, cecal, and colonic digesta were collected; ileal digesta was pooled within replicate for NSP analysis (n=6 per treatment). Data were analyzed as a linear mixed model using replicate and block as random effects, and treatment as a fixed effect. Compared to LF, the HF diet reduced (P&lt; 0.01) apparent ileal digestibility (AID) of total NSP (32.7 vs. 16.3%), insoluble NSP (50.0 vs. 21.5%), and insoluble arabinoxylan (29.8 vs. 15.4%). Xylanase (HF+XY vs. HF) increased (P&lt; 0.01) AID of total NSP by 39.8% (27.1 vs. 16.3%) and insoluble NSP by 34.0%. This may be attributed to xylanase increasing AID of total arabinoxylan by 54.5% over HF, 44.5% over LF, and 56.9% over HF+AX (33.0, 15.1, 18.3, and 14.2%, respectively; P=0.02). In conclusion, increasing insoluble fiber reduces NSP digestibility, but xylanase can increase AID of arabinoxylan and NSP. Supplementing an arabinoxylan-oligosaccharide, a potential release product of the xylanase, did not increase NSP digestibility.

172 Increasing inclusion of fermentable fiber decreases nutrient digestibility in grower pigs

Fermentable fiber may increase endogenous losses of P and AA, thereby reducing apparent nutrient digestibility. Acacia gum fiber with medium-to-high fermentability and low viscosity was used to investigate its effect on apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients, and standardized total tract digestibility (STTD) of P in grower pigs. A P-free basal diet (49% corn starch; 18% bovine plasma protein) was formulated to measure basal endogenous P losses (EPL). Three diets were formulated to include 2.5, 5.0, or 7.5% acacia gum fiber at the expense of corn starch in the P-free basal diet. Diets contained 16.1–17.4% CP and 0.31–0.33% total P (DM-basis). The 4 diets were fed to 8 ileal-cannulated barrows (initial BW, 54.6 kg) for four 9-d periods in a double 4 × 4 Latin square. Apparent hindgut fermentation (AHF) was ATTD minus AID. Increasing inclusion of acacia gum quadratically decreased (P &lt; 0.01) AID of DM (∆ 11.1%), linearly decreased (P &lt; 0.05) ATTD of DM (∆ 1.7%) CP (∆ 1.2%), and quadratically increased (P &lt; 0.05) AHF of DM (∆ 9.4%). Basal EPL were 391 and 377 mg/kg DM intake (DMI) for ileum and total tract, respectively. Increasing inclusion of fiber linearly increased (P &lt; 0.05) ileal EPL (∆ 184 mg/kg DMI), and tended to linearly increase (P &lt; 0.10) EPL for total tract (∆ 243 mg/kg DMI). Dietary inclusion of acacia gum tended to linearly decrease (P &lt; 0.10) AID of P, but did not affect (P &gt; 0.10) ATTD, or STTD of P. In conclusion, increasing inclusion of fermentable, low viscous acacia gum fiber decreased diet digestibility of DM and ATTD of CP, but did not affect total tract P digestibility, indicating that increasing fermentable fiber did not increase specific endogenous losses of P in the total tract.

Thermomechanical and enzyme-facilitated processing of soybean meal enhanced in vitro kinetics of protein digestion and protein and amino acid digestibility in weaned pigs

Soybean meal (SBM) contains anti-nutritional factors (ANF) that may limit kinetics and total extent of protein digestion in pigs. This study evaluated the effects of thermomechanical and enzyme-facilitated (TE) processing on in vitro kinetics of crude protein (CP) digestion and CP and amino acid (AA) digestibility in weaned pigs. Each batch of SBM (48% CP) was divided into two parts: non-processed SBM as control vs. thermomechanical and enzyme-facilitated processed soybean meal (TES) as the experimental group. For digestion kinetics, samples (three batches of non-processed SBM vs. TES) were incubated in triplicate sequentially with pepsin at pH 3.5 for 1.5 h (stomach phase) and subsequently with pancreatin and bile extract at pH 6.8 for 0, 0.5, 1, 2, 4, or 6 h (small intestine phase). Protein was classified into CPfast, CPslow, and CPresistant corresponding to CP digested within the first 0.5 h, from 0.5 to 4 h, and after 4 h plus undigested CP, respectively. Eight weaned barrows (Large White × Duroc, 9.43 ± 0.40 kg) were surgically fitted with a T-cannula at the terminal ileum. Pigs were randomly assigned to a Youden square with three diets over four periods. The three diets were an N-free diet and two diets using 40% SBM or TES as the sole source of AA with Cr2O3 as an indigestible marker. Each period included sequentially a 5-d adaptation, 2-d collection of feces, and 2-d collection of ileal digesta. The TE processing reduced ANF content in TES by 91% for lectin, 22% for trypsin inhibitor activity, 75% for β-conglycinin, and 62% for glycinin compared with SBM. In vitro, TE processing increased (P < 0.05) digested CP by 5.6% and enhanced the kinetics of CP digestion by tending to increase (P = 0.056) CPfast by 25% and reducing (P < 0.05) CPslow and CPresistant by 48% and 11%, respectively. In pigs, TE processing increased (P < 0.05) apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of CP in TES by 2.3% and 2.1%, respectively. The TE processing increased (P < 0.05) AID and SID of all AA up to 3.3%, except for AID of Pro and SID of Pro, Gly, and Cys. The TE processing did not change reactive Lys or Lys:CP but increased (P < 0.05) SID of Lys and reactive Lys by 3%. Combined, the greater in vitro digestion kinetics matched the greater in vivo AID and SID of CP in TES and lower ANF compared with SBM. Thus, TE processing created a protein source that is digested faster and to a greater extent than SBM, thereby lowering the chance of protein fermentation.

Nutrient digestibility of soybean products in grower-finisher pigs1

Solvent extraction of soybean creates soybean meal (SBM), but an array of other soybean products can be created using further processing of SBM or soybean. For accurate inclusion of these products in pig feed, characterization of digestible AA profile and energy value is required. Soybean products from processes such as extrusion (EX) of soybean and thermo-mechanical (TM) treatment, bioconversion using fermentation or enzymes (BC), and ethanol-water extraction (EW) of soybean meal were collected together with SBM. These 9 soybean products were tested in cornstarch-based diets together with an N-free diet for a total of 10 diets. Ten ileal-cannulated barrows (30.4 ± 0.7 kg initial BW) were fed 10 diets at 2.8 times maintenance DE for six 9-d periods with a 6 (periods) × 10 (pigs) Youden square. The control SBM contained 47.0% CP, 1.4% ether extract, and ADF 6.0%. The 9 soybean products contained 35.6% to 66.4% CP, 0.9% to 21.6% ether extract, and 4.4% to 8.0% ADF. The EW soybean products were high in CP (>61%), whereas the 2 EX soybean products were low in CP (<36%) but high in ether extract (≥19%). Chemically available Lys ranged from 92.6% to 100% of total Lys, indicating that minor Lys damage occurred during processing. The apparent total tract digestibility (ATTD) of energy was lower (P < 0.05) for soybean products with greater ether extract and ADF content than SBM, and varied among soybean products. The standardized ileal digestibility (SID) did not differ (P > 0.05) among soybean products for most AA, except for lower SID of Arg, Ile, Leu, Lys, Phe, and Tyr (P < 0.05) for EX2 and BC1 than other soybean products. The DE and predicted NE value did not differ (P > 0.05) among soybean products. The greater SID AA content (P < 0.05) in EW, BC, and TM1 soybean products than SBM was mainly a result of greater total AA content due to removal of other macronutrients. In conclusion, extrusion of soybean creates soybean products with a greater energy value but lower ATTD of energy and lower SID AA content than SBM. Further processing of SBM creates soybean products with greater CP and SID AA content but similar SID of AA than SBM. Thus, new technologies to process SBM or soybean create high-value ingredients to be included in pig diets, especially for young pigs with high nutritional requirements.

Digestibility of branched and linear α-gluco-oligosaccharides in vitro and in ileal-cannulated pigs

Isomalto-oligosaccharides (IMOs) may promote health by modulating intestinal microbiota. We hypothesized that the proportion of α-(1 → 6) linkages in IMOs determines their digestibility. Ileal-cannulated pigs were fed diets containing IMO, IMO-DP3 with a greater DP and more α-(1 → 4) linkages, and digestible or resistant maltodextrins. Oligosaccharides were analysed by high-performance anion-exchange chromatography. Compared to IMO, IMO-DP3 contained more panose (18.6 vs. 10.3%) but less isomaltose (7.5 vs. 22.3%) and isomaltotriose (6.1 vs. 12.6%). The apparent ileal digestibility of dry matter were 3% greater for IMO-DP3 and digestible maltodextrin than resistant maltodextrin; the digestibility of IMO was not different from other oligosaccharides. Ileal propionate, isovalerate, and total SCFA was greater for IMO-DP3 and digestible maltodextrin than IMO. In conclusion, IMO was less digestible than IMO-DP3. Structural properties of IMOs are important determinants of their functional properties within the porcine digestive tract.

PSVII-16 Galactosylated chitosan-oligosaccharides have anti-adhesive effect against enterotoxigenic Escherichia coli in piglets

Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrhea in piglets. In vitro, high molecular weight β-galactosylated chitosan-oligosaccharides (Gal-COS) had strong anti-adhesive activity against ETEC-expressing K88 fimbriae (ETEC K88) binding to porcine erythrocytes. This study assessed the effects of Gal-COS differing in structure on anti-adhesive properties against ETEC in a small intestinal segment perfusion (SISP) model in 8 piglets (BW 10 kg; 5-wk old). With 10 jejunal segments in each pig, 5 segments were infected with ETEC K88, and the other 5 segments were infused with saline (non-ETEC). Every 2 paired segments (ETEC or non-ETEC) from the same pig were treated for 8 h with 64 ml of 10 g L-1 of one of the following test products: 1) α-Gal-COS; 2) β-Gal-COS; 3) exopolysaccharides produced by Lactobacillus reuteri; and 4) raffinose in a double 4 × 4 Latin square with a saline control. Infection by ETEC K88 was verified by quantitative PCR. Net fluid loss was calculated as difference of fluid loss between ETEC segment and its paired non-ETEC segment. Data were analyzed using the mixed model with segment and test product as fixed effects, and pig as random effect. Number of eubacterial rRNA genes was 10-fold greater (P < 0.001) in ETEC segments than non-ETEC segments, indicating that ETEC K88 accounted for > 90% of bacterial gene counts. Test product did not affect (P > 0.10) the number of ETEC bacteria in the outflow fluid. Furthermore, net fluid loss caused by ETEC tended (P = 0.08) to be decreased by β-Gal-COS compared to all other treatments. In conclusion, the in vivo SISP model confirmed that Gal-COS had anti-diarrheal effects, indicating that β-Gal-COS is a potential feed additive to reduce the ETEC-induced diarrhea in piglets.

114 Role of fiber in promoting health in nursery pigs

In swine production, use of feed antibiotics as antimicrobial growth promotant will be reduced; thus, feed alternatives to manage gut health are required to prevent post-weaning diarrhea. Dietary fiber, resistant starch, oligosaccharides, and exo-polysaccharides are carbohydrates are nutritional tools that may be part of managing gut health in pigs. Antibiotics are hypothesized to influence gut health via modulation of intestinal microbial profiles; fermentation and intestinal inflammation are considered important mechanisms. As alternative, dietary fiber sources differ in 2 key properties: fermentability and viscosity. Rapid fiber fermentation is associated with changes in microbial profiles and increased metabolite production. Recently, microbial composition was hypothesized to be less important, and it was thought that the focus should be on combined output of metabolites. Increased viscosity has been associated with increased gut content of virulence factors linked with diarrhea. Fiber properties may manipulate retention time and physico-chemical properties of the undigested residue. Starch is mostly digested and absorbed as glucose; however, resistant starch is not digested but fermented instead. Resistant starch acts as fermentable fiber but is unique, because it specifically increases digesta abundance of bifidobacteria that are associated with improved gut health. Oligosaccharides may be rapidly fermented and thereby influence intestinal microbial profiles and metabolite production. Raw materials and some feed additives both influence kinetics of fermentation and have prebiotic activity. Their kinetics of fermentation should be quantified so that it can be considered in feed formulation. Finally, exopolysaccharides from Lactobacillus reuteri and unique oligosaccharides may serve as scavenger molecules for pathogenic bacteria, e.g., enterotoxigenic Escherichia coli (ETEC), to bind to instead of adhering to the gut wall, thereby avoiding diarrhea initiation. In conclusion, dietary fiber and other carbohydrates may be important solutions to maintain gut health when antibiotics are removed as growth promotants from swine feeds.

PSIV-7 Diet nutrient digestibility and growth performance in weaned pigs fed steam-exploded canola meal

Canola meal (CM) is widely included in swine diets, but its fiber matrix compromises its nutritional value. Whether steam-explosion with high pressure can increase nutrient digestibility of CM and hence growth performance in pigs is unknown. To explore, Brassica napus CM was processed with steam pressure at 700 or 1,100 kPa for 5 min followed by a sudden release of pressure to produce steam-exploded CM7 and CM11, respectively. Four diets containing 20% CM, CM7, CM11, or soybean meal (SBM) were formulated to provide 2.3 Mcal net energy (NE)/kg and 5.1 g standardized ileal digestible lysine/Mcal NE. From 2 weeks post-weaning, 256 pigs (BW, 10 kg) were fed the 4 diets for 4 weeks in a randomized complete block design with 16 blocks and 4 pigs per pen. Apparent total tract digestibility (ATTD) of dry matter (DM), crude protein (CP), and gross energy (GE) was 4.8, 4.3 and 3.7%-units lower (P < 0.05), respectively, for the 3 CM diets than the SBM diet, whereas diet digestible energy (DE) value was not different. Steam-explosion of CM did not affect diet ATTD of DM and GE, but reduced (P < 0.05) diet ATTD of CP. For the entire trial (day 1–28), steam-explosion at either 700 or 1,100 kPa increased (P < 0.05) average daily feed intake (ADFI) of CM, but the CM diet had lower (P < 0.05) ADFI than the SBM diet. Average daily gain (ADG) did not differ among the 4 diets. Consequently, feed efficiency (G:F) was greater (P < 0.05) for the 3 CM diets than the SBM diet. In conclusion, steam-explosion of CM did not increase diet nutrient digestibility or growth performance of weaned pigs.

Metagenomic reconstructions of gut microbial metabolism in weanling pigs

BACKGROUND

The piglets' transition from milk to solid feed induces a succession of bacterial communities, enhancing the hosts' ability to harvest energy from dietary carbohydrates. To reconstruct microbial carbohydrate metabolism in weanling pigs, this study combined 16S rRNA gene sequencing (n = 191) and shotgun metagenomics (n = 72).

RESULTS

Time and wheat content in feed explained most of the variation of the microbiota as assessed by 16S rRNA gene sequencing in weanling pigs. De novo metagenomic binning reconstructed 360 high-quality genomes that represented 11 prokaryotic and 1 archaeal phylum. Analysis of carbohydrate metabolism in these genomes revealed that starch fermentation is carried out by a consortium of Firmicutes expressing extracellular α-(1 → 4)-glucan branching enzyme (GH13) and Bacteroidetes expressing periplasmic neopullulanase (GH13) and α-glucosidase (GH97). Fructans were degraded by extracellular GH32 enzymes from Bacteriodetes and Lactobacillus. Lactose fermentation by β-galactosidases (GH2 and GH42) was identified in Firmicutes. In conclusion, the assembly of 360 high-quality genomes as the first metagenomic reference for swine intestinal microbiota allowed identification of key microbial contributors to degradation of starch, fructans, and lactose.

CONCLUSIONS

Microbial consortia that are responsible for degradation of these glycans differ substantially from the microbial consortia that degrade the same glycans in humans. Our study thus enables improvement of feeding models with higher feed efficiency and better pathogen control for weanling pigs.

Carbohydrate level and source have minimal effects on feline energy and macronutrient metabolism

The carnivorous nature of the domestic cat makes feline metabolism of carbohydrates unique. The cats' glycemic response has been previously studied, with variable outcomes in response to carbohydrate level and source, but is an important response to understand how to control glycemia. The objectives of this study were to determine the glucose and insulin responses of cats fed 3 commercial diets differing in carbohydrate content and source, and to investigate the effects of diet on RQ, energy expenditure (EE), and glycemic response. Domestic shorthair cats (=19, 10 males, 9 females) of similar age (4.3 ± 0.48 yr, mean ± SD) and of ideal body condition score were used. Cats were fed, once a day, 1 of 3 commercial diets that differed in their perceived glycemic response (PGR; 36.8%, 30.7%, and 23.6% starch for high, medium, and low PGR, respectively) with cats cycling through all diets in 3 periods in 6 complete and 1 incomplete 3 × 3 Latin square. Each period consisted of 8 d of adaptation to the diet, followed by 21-h calorimetry measurements, and real-time interstitial glucose measurements on day 9. On day 10, sequential blood sampling was completed to determine blood glucose and insulin. BW and ME intake did not differ among treatments. EE in the fasted state did not differ among treatments (P = 0.160), whereas postprandial EE was highest for the high PGR diet compared with the medium PGR and low PGR diets (P < 0.001). In conclusion, cats revealed a prolonged postprandial glucose and insulin response compared with other monogastric animals, yet diet effects were minimal. Overall, interstitial glucose measures were less variable than serum glucose measurements and followed a parallel pattern to RQ. Therefore, going forward, calorimetry and continuous interstitial glucose monitoring should be considered as less invasive alternatives to repeated blood sampling.

Reduced Feed Intake, Rather than Increased Energy Losses, Explains Variation in Growth Rates of Normal-Birth-Weight Piglets

Background

Substantial variation in growth rates exists in normal-birth-weight piglets, possibly due to differences in energy efficiency. Within this population, slow growth rates are associated with reduced insulin sensitivity. Slowly digestible starch (SDS) may improve growth efficiency in slowly growing pigs, because it reduces postprandial blood glucose.

Objective

The aim of this study was to investigate maintenance energy requirements and efficiency of energy used for growth (incremental energy efficiency) of slow-growing or fast-growing piglets (SG-pigs and FG-pigs, respectively) with equal birth weight that were fed either an SDS or a rapidly digestible-starch (RDS) diet.

Methods

Sixteen groups of either five 10-wk-old SG-pigs (mean ± SD: 11.3 ± 1.4 kg) or FG-pigs (15.1 ± 1.7 kg) were housed in climate respiration chambers and fed diets containing 40% RDS or SDS for 2 wk. In week 1, feed was available ad libitum. In week 2, feed supply was restricted to 65% of the observed weekly averaged feed intake [kJ · kg body weight (BW)-0.6 · d-1] in week 1. After week 2, pigs were feed deprived for 24 h, after which heat production was determined. Energy balances, apparent total tract digestibility (ATTD), and incremental energy efficiencies were calculated and analyzed using a general linear model.

Results

Gross energy intake (kJ · kg BW-0.6 · d-1) was 4% greater (P = 0.047) for FG-pigs than for SG-pigs. ATTD of fat was 6%-units greater (P = 0.003) for RDS-fed than for SDS-fed pigs. Fasting heat production and incremental energy efficiencies did not differ between pig types or diets. Incremental use of metabolizable energy for fat retention was 2% units (P = 0.054) greater for RDS-fed than SDS-fed pigs.

Conclusions

A lower energy intake rather than greater maintenance requirements or lower energy efficiency explains the slow growth of SG-pigs. Incremental RDS intake increased fat deposition more than SDS, whereas energy efficiency was not affected. Thus, feeding SDS instead of RDS does not improve growth efficiency but may result in slightly leaner pigs.

Impact of probiotic Lactobacillus sp. on autochthonous lactobacilli in weaned piglets

AIMS

This study aimed to determine whether host-adapted lactobacilli exhibit superior survival during intestinal transit relative to nomadic and free-living organisms, and to characterize the impact of probiotic lactobacilli on autochthonous lactobacilli.

METHODS AND RESULTS

Mixed cultures of Lactobacillus casei K9-1 and Lactobacillus fermentum K9-2, or reutericyclin producing Lactobacillus reuteri and its isogenic mutant were fed to piglets as freeze-dried culture, or as part of fermented feed. Lactobacilli in digesta and faecal samples were quantified by strain-specific quantitative PCR (qPCR), high-resolution-melting curve qPCR, and high-throughput sequencing of 16S rRNA gene sequence tags. The abundance of the host adapted L. reuteri in digesta and faeces was higher (P < 0·05) when compared to L. casei or L. fermentum. Feed fermentation or chemical acidification of feed reduced (P < 0·05) cell counts of Lactobacillus salivarius in colonic digesta. The reutericyclin producing L. reuteri TMW1.656 transiently reduced (P < 0·05) the faecal abundance of lactobacilli. However, the overall impact of probiotic intervention on autochthonous lactobacilli was minor.

CONCLUSIONS

The vertebrate host-adapted L. reuteri survives better during intestinal transit of piglets compared to L. casei and L. fermentum.

SIGNIFICANCE AND IMPACT OF THE STUDY

Ecology and lifestyle of Lactobacillus strains may be suitable criteria for selection of probiotic strains for use in swine production.

Feed preference of weaned pigs fed diets containing soybean meal, Brassica napus canola meal, or Brassica juncea canola meal

Brassica napus and Brassica juncea canola meal (CM) may replace soybean meal (SBM) in pig diets, but differ in fiber, glucosinolates content and profile. Preference of weaned pigs provided double-choice selections to diets containing 20% SBM, B. napus CM, or B. juncea CM was evaluated in two studies. In experiment 1, 216 pigs (9.4 ± 1.6 kg initial BW) were housed in 27 pens of 8 pigs (four gilts and four barrows). In experiment 2, 144 pigs (8.9 ± 1.1 kg) were housed in 36 pens of 4 pigs (two gilts and two barrows). Pigs were offered three dietary choices: B. napus CM with SBM as reference (B. napus CM [SBM]), B. juncea CM with SBM as reference (B. juncea CM [SBM]), and B. juncea CM with B. napus CM as reference (B. juncea CM [B. napus CM]) in a replicated 3 × 3 Latin square. Diets were formulated to provide 2.4 Mcal NE/kg and 4.5 g standardized ileal digestible Lys/Mcal NE and were balanced using canola oil and crystalline AA. Each pair of diets was offered in two self-feeders per pen as mash (experiment 1) or pellets (experiment 2) during three test-periods of 4-d, followed by a 3-d non-test period when a common diet was offered in both feeders. Feeders with different diets were rotated daily among pens during preference periods for both experiments, and feeder positions (right or left) were switched daily in experiment 2. Prior to the study and between periods, pigs were fed non-test diets containing SBM (experiment 1) or without test feedstuffs (experiment 2). Overall in both experiments, pigs preferred (P < 0.001) SBM over B. napus and B. juncea CM diets, and preferred (P < 0.001) B. napus over B. juncea CM diet. Dietary choice did not affect (P > 0.05) growth performance in both experiments, except for greater G:F (P < 0.05) for pigs fed the B. juncea CM [B. napus CM] diets than pigs fed the B. napus CM [SBM] or B. juncea CM [SBM] diets in experiment 1. In conclusion, weaned pigs preferred SBM over CM diets when given a choice, and preferred B. napus over the B. juncea diet that contained more total glucosinolates especially gluconapin. Weaned pigs fed the B. juncea CM [B. napus CM] diets in the double-choice selection did not reduce feed intake, weight gain, and G:F compared to pigs fed the B. napus CM [SBM] or B. juncea CM [SBM] diets.

Apparent and true ileal and total tract digestibility of fat in canola press-cake or canola oil and effects of increasing dietary fat on amino acid and energy digestibility in growing pigs

Digestibility of remaining oil in canola press-cake (CPC) may be lower than that of extracted, liquid canola oil (CO) because oil may be partly entrapped in the CPC matrix. To determine true digestibility of fat in ingredients, endogenous fat losses should be estimated. Dietary fat may interact with digestion of other dietary components. To test these hypotheses, 10 ileal-cannulated pigs (initial BW, 25.4 kg) were fed 10 diets for 8 periods in a 10 × 8 Youden square. A basal diet was formulated based on wheat, barley, and canola meal. The 4 CPC and 4 CO test diets were prepared by replacing identical portion of basal diet with 10%, 20%, 30%, or 40% CPC, or 1.5%, 3.0%, 4.5%, or 6.0% CO, respectively, to match the fat content of CPC diet with CO diet at each fat level. An N-free diet based on corn starch was prepared to measure basal endogenous losses of AA. Apparent total tract digestibility (ATTD) and apparent ileal digestibility (AID) of acid-hydrolyzed ether extract (AEE) were calculated for each diet. True ileal digestibility (TID) and true total tract (TTTD) digestibility of AEE in CPC and CO, and total endogenous losses of AEE were estimated by regressing apparent digestible AEE (g/kg of DMI) against dietary AEE intake (g/kg of DM) at the total tract and distal ileum, respectively. The mean AID and ATTD of AEE in CPC diets were 78.9% and 61.5%, which were lower ( < 0.01) than 81.9% and 63.4% in CO diets. Apparent ileal and total tract digestible AEE content in CPC and CO diets increased linearly ( < 0.01) with increasing AEE intake. Endogenous losses of AEE were greater ( < 0.05) for the total tract than for the ileum (23.4 vs. 9.4 g/kg of DMI). Dietary fat source did not affect ( > 0.05) total tract or ileal endogenous losses of AEE. The TID and TTTD of AEE in CPC were 92.3% and 94.5%, respectively, lower ( < 0.01) than 96.5% and 100% in CO. Increasing dietary inclusion of CO linearly increased ( < 0.001) standardized ileal digestibility (SID) of CP, Lys, Met, Thr, and Trp, and quadratically increased ( < 0.001) the AID and ATTD of energy in the basal part of the test diets. In conclusion, CPC had lower TID and TTTD of AEE than CO. Dietary fat source did not affect endogenous losses of AEE. The lower digestibility of AEE in CPC than in CO indicates that fat digestibility of CPC should be considered to predict its nutritional value accurately. Dietary inclusion of CO may increase digestibility of CP and energy originating from the balance of the diet.

Whole-Grain Starch and Fiber Composition Modifies Ileal Flow of Nutrients and Nutrient Availability in the Hindgut, Shifting Fecal Microbial Profiles in Pigs

Background: Changes in whole-grain chemical composition can affect the site of nutrient digestion, which may alter substrate availability and gut microbiota composition.Objective: This study elucidated the function of whole-grain fermentable fiber composition on ileal substrate flow, hindgut substrate availability, and subsequent gut microbial profiles in pigs.Methods: Five whole grains-1) high-fermentability, high-β-glucan hull-less barley (HFB); 2) high-fermentability, high-amylose hull-less barley (HFA); 3) moderate-fermentability hull-less barley (MFB); 4) low-fermentability hulled barley (LFB); or 5) low-fermentability hard red spring wheat (LFW)-were included at 800 g/kg into diets fed to ileal-cannulated growing pigs for 9 d in a 6 (periods) × 5 (diets) Youden square. Digesta were analyzed for nutrient flow and microbial composition via 16S ribosomal RNA gene sequencing.Results: The consumption of fermentable whole grains, HFB, and HFA increased (P < 0.05) ileal starch flow by 69% and dry matter flow by 37% compared with LFB and LFW intakes. The consumption of HFB and HFA increased (P < 0.05) fecal Firmicutes phylum abundance by 26% and 21% compared with LFB intake and increased (P < 0.05) fecal Dialister genus abundance, on average, by 98% compared with LFB and LFW intakes. Fecal Sharpea and Ruminococcus genera abundances increased (P < 0.05) with HFB intake compared with LFB and LFW intakes. In contrast, the consumption of LFB increased (P < 0.05) fecal Bacteroidetes phylum abundance by 43% compared with MFB intake. Ileal starch flow and fecal Firmicutes abundance were positively correlated and determined by using principal components analysis.Conclusions: Increasing dietary fermentable fiber from whole grains can increase ileal substrate flow and hindgut substrate availability, shifting the fecal microbiota toward Firmicutes phylum members. Thus, digesta substrate flow is important to shape gut microbial profiles in pigs, which indicates that the manipulation of substrate flow should be considered as a tool to modulate gut microbiota composition.

Identification and quantification of virulence factors of enterotoxigenic Escherichia coli by high-resolution melting curve quantitative PCR

BACKGROUND

Diagnosis of enterotoxigenic E. coli (ETEC) associated diarrhea is complicated by the diversity of E.coli virulence factors. This study developed a multiplex quantitative PCR assay based on high-resolution melting curves analysis (HRM-qPCR) to identify and quantify genes encoding five ETEC fimbriae related to diarrhea in swine, i.e. K99, F41, F18, F6 and K88.

METHODS

Five fimbriae expressed by ETEC were amplified in multiple HRM-qPCR reactions to allow simultaneous identification and quantification of five target genes. The assay was calibrated to allow quantification of the most abundant target gene, and validated by analysis of 30 samples obtained from piglets with diarrhea and healthy controls, and comparison to standard qPCR detection.

RESULTS

The five amplicons with melting temperatures (Tm) ranging from 74.7 ± 0.06 to 80.5 ± 0.15 °C were well-separated by HRM-qPCR. The area of amplicons under the melting peak correlated linearly to the proportion of the template in the calibration mixture if the proportion exceeded 4.8% (K88) or <1% (all other amplicons). The suitability of the method was evaluated using 30 samples from weaned pigs aged 6-7 weeks; 14 of these animals suffered from diarrhea in consequence of poor sanitary conditions. Genes encoding fimbriae and enterotoxins were quantified by HRM-qPCR and/or qPCR. The multiplex HRM-qPCR allowed accurate analysis when the total gene copy number of targets was more than 1 × 105 / g wet feces and the HRM curves were able to simultaneously distinguish fimbriae genes in the fecal samples. The relative quantification of the most abundant F18 based on melting peak area was highly correlated (P < 0.001; r2 = 0.956) with that of individual qPCR result but the correlation for less abundant fimbriae was much lower.

CONCLUSIONS

The multiplex HRM assay identifies ETEC virulence factors specifically and efficiently. It correctly indicated the predominant fimbriae type and additionally provides information of presence/ absence of other fimbriae types and it could find broad applications for pathogen diagnosis.

Whole-Grain Fiber Composition Influences Site of Nutrient Digestion, Standardized Ileal Digestibility of Amino Acids, and Whole-Body Energy Utilization in Grower Pigs

BACKGROUND

Variant chemical composition and physical structure of whole grains may change the site of energy digestion from the small to the large intestine.

OBJECTIVE

We determined the site of nutrient digestion, standardized ileal digestibility (SID) of amino acids (AAs), and net energy (NE) value of barley cultivars that vary in nutrient composition compared with wheat.

METHODS

Ileal-cannulated barrows (27.7 kg initial body weight) were fed diets containing 800 g whole grains/kg alongside a basal and nitrogen-free diet for calculations in a 6 (period) × 7 (diet) Youden square. Diets included 1 of 5 whole grains-1) high-fermentable, high-β-glucan, hull-less barley (HFB); 2) high-fermentable, high-amylose, hull-less barley (HFA); 3) moderate-fermentable, hull-less barley (MFB); 4) low-fermentable, hulled barley (LFB); and 5) low-fermentable, hard red spring wheat (LFW). Intestine nutrient flow and whole-body energy utilization were tested and explained by using whole-grain and digesta confocal laser scanning.

RESULTS

Starch apparent ileal digestibility was 14-29% lower (P < 0.05) in HFB and HFA than in MFB, LFB, and LFW due to the unique embedding of starch within the protein-fiber matrix of HFB and the high amylose content in HFA. Starch hindgut fermentation was 50-130% higher (P < 0.05) in HFB and HFA than in MFB, LFB, and LFW. The SID of indispensable AAs was lower (P < 0.05) in HFB and HFA than in MFB, LFB, and LFW. NE value was 18% higher (P < 0.05) for HFB than for HFA and was not different from MFB, LFB, and LFW.

CONCLUSIONS

Whole grains high in fermentable carbohydrates shifted digestion from the small intestine to the hindgut. NE value depended on the concentration of fermentable fiber and starch and digestible protein, ranging from 2.12-1.76 Mcal/kg in barley to 1.94 Mcal/kg in wheat. High-fiber whole grains may be used as energy substrates for pigs; however, the reduced SID of AAs requires titration of indispensable AAs to maintain growth.