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.

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 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-ß-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.

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-ß-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.

Feed Fermentation with Reuteran- and Levan-Producing Lactobacillus reuteri Reduces Colonization of Weanling Pigs by Enterotoxigenic Escherichia coli.

This study determined the effect of feed fermentation with Lactobacillus reuteri on growth performance and the abundance of enterotoxigenic Escherichia coli (ETEC) in weanling piglets. L. reuteri strains produce reuteran or levan, exopolysaccharides that inhibit ETEC adhesion to the mucosa, and feed fermentation was conducted under conditions supporting exopolysaccharide formation and under conditions not supporting exopolysaccharide formation. Diets were chosen to assess the impact of organic acids and the impact of viable L. reuteri bacteria. Fecal samples were taken throughout 3 weeks of feeding; at the end of the 21-day feeding period, animals were euthanized to sample the gut digesta. The feed intake was reduced in pigs fed diets containing exopolysaccharides; however, feed efficiencies did not differ among the diets. Quantification of L. reuteri by quantitative PCR (qPCR) detected the two strains used for feed fermentation throughout the intestinal tract. Quantification of E. coli and ETEC virulence factors by qPCR demonstrated that fermented diets containing reuteran significantly (P < 0.05) reduced the copy numbers of genes for E. coli and the heat-stable enterotoxin in feces compared to those achieved with the control diet. Any fermented feed significantly (P < 0.05) reduced the abundance of E. coli and the heat-stable enterotoxin in colonic digesta at 21 days; reuteran-containing diets reduced the copy numbers of the genes for E. coli and the heat-stable enterotoxin below the detection limit in samples from the ileum, the cecum, and the colon. In conclusion, feed fermentation with L. reuteri reduced the level of colonization of weaning piglets with ETEC, and feed fermentation supplied concentrations of reuteran that may specifically contribute to the effect on ETEC.

High Amylose Starch with Low In Vitro Digestibility Stimulates Hindgut Fermentation and Has a Bifidogenic Effect in Weaned Pigs.

BACKGROUND: Dietary amylose resists enzymatic digestion, thereby providing a substrate for microbial fermentation that stimulates proliferation of beneficial microbiota and production of short-chain fatty acids (SCFAs) in the large intestine of pigs and humans. However, the effect of increasing dietary amylose in pigs immediately postweaning on growth, nutrient digestibility and flow, and intestinal microbial and SCFA profiles has not been studied and can be used as a model for newly weaned human infants. OBJECTIVE: We studied the effects of increasing dietary amylose on growth, nutrient digestibility, and intestinal microbial and metabolite profiles in weaned pigs. METHODS: Weaned pigs (n = 32) were randomly allocated to 1 of 4 diets containing 67% starch with 0%, 20%, 28%, or 63% amylose for 21 d. Subsequently, pigs were killed to collect feces and digesta for measuring starch digestion and microbial and metabolite profiles. RESULTS: Feeding weaned pigs 63% compared with 0%, 20%, and 28% amylose decreased (P < 0.05) feed intake by 5% and growth by ≥ 12%. Ileal digestibility of dry matter decreased (P < 0.05) by 10% and starch by 9%, thereby increasing (P < 0.05) hindgut fermentation, cecal and colonic total SCFAs, and colonic Bacteroides, and lowering (P < 0.01) ileal, cecal, and colonic pH in pigs consuming 63% compared with 0%, 20%, and 28% amylose. Cecal and colonic Bifidobacteria spp. increased by 14-30% (P < 0.05) and Clostridium clusters IV and XIVa were decreased (P < 0.01) in pigs consuming 63% compared with 0%, 20%, and 28% amylose. CONCLUSION: Increasing dietary amylose in pigs immediately postweaning stimulated hindgut fermentation and Bifidobacteria spp., thereby manipulating the gut environment, but also reduced intake and growth. An optimum dietary amylose concentration should be determined, which would maintain desired growth rate and gut environment in weaned pigs.

Exopolysaccharides synthesized by Lactobacillus reuteri protect against enterotoxigenic Escherichia coli in piglets.

Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrhea in piglets; ETEC cells colonize the intestinal mucosa with adhesins and deliver toxins that cause fluid loss. This study determined the antiadhesive properties of bacterial exopolysaccharides (reuteran and levan) and related glycans (dextran and inulin) in a small intestinal segment perfusion (SISP) model. The SISP model used 10 jejunal segments from 5-week-old piglets. Five segments were infected with ETEC expressing K88 fimbriae (ETEC K88), while five segments were treated with saline. Every two segments (ETEC and non-ETEC infected) were infused with 65 ml of 10 g liter(-1) of glycans or saline (control) for 8 h. High-resolution melting-curve (HRM) quantitative PCR (qPCR) indicated that E. coli is the dominant bacterium in infected segments, while other bacteria were predominant in noninfected segments. Infection by ETEC K88 was also verified by qPCR; gene copy numbers of K88 fimbriae and the heat-labile toxin (LT) in mucosal scrapings and outflow fluid of infected segments were significantly higher than those in noninfected segments. Genes coding for K88 fimbriae and LT were also detected in noninfected segments. LT amplicons from infected and noninfected segments were 99% identical over 481 bp, demonstrating the presence of autochthonous ETEC K88. All glycans reduced fluid loss caused by ETEC K88 infection. Reuteran tended (P = 0.06) to decrease ETEC K88 levels in mucosal scraping sample, as judged by qPCR. Fluorescent in situ hybridization analysis demonstrated that reuteran significantly (P = 0.012) decreased levels of adherent ETEC K88. Overall, reuteran may prevent piglet diarrhea by reducing adhesion of ETEC K88.

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 ±â€…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.

Feeding a Multi-Enzyme Blend to Enhance the Nutrient Digestibility of Wheat-Canola Expeller Diets in Ileal-Cannulated Weaned Pigs.

Canola expeller (CE) contains ~200 g/kg residual oil, but also fiber that impairs nutrient digestibility in weaned pigs. To study if feed enzymes increase digestibility, six diets containing either the basal or two CE samples mixed in at 250 g/kg (CE-A or CE-B) were formulated with or without a multi-enzyme blend containing cellulase, xylanase, glucanase, amylase, protease, invertase, and pectinase. The basal diet containing 620 g/kg wheat and 150 g/kg barley served as control. Twelve ileal-cannulated barrows (9-15 kg) were fed the six diets in a replicated 6 (pigs) × 3 (periods) Youden square. Ileal digestibility of gross energy and amino acids was 5% greater for basal than CE diets without differences between CE samples. Diet energy values were 4% greater for CE than basal diets due to residual oil in CE. Inclusion of the multi-enzyme blend increased total tract digestibility of energy of the basal but not CE diets by 2%. Net energy value was greater for CE-A than CE-B because CE-A contained more residual oil. In conclusion, feeding 250 g/kg CE increased diet energy values; thus, CE can substitute added fat in weaned pig diets. Feeding the multi-enzyme blend increased the energy digestibility of wheat and barley-based diets fed to weaned pigs. However, research is needed to identify enzyme combinations that increase the nutrient digestibility of CE.

Eat like a Pig to Combat Obesity.

Obesity and related metabolic health issues are a growing human threat, with many theories regarding its causes. In swine, physiologically alike to humans, considerable knowledge on obesity mechanisms has been accumulated. Calorie counting is the basis for managing swine diets and applied with great accuracy. Epigenetic programing predisposes pigs to insulin insensitivity, but pigs seem to sense this insensitivity and consequently eat less, preventing obesity. Pigs naturally prefer to eat small breakfasts and large dinners. Deviating from this eating pattern or providing diets with a high glycemic burden can trigger obesity; however, pigs will restrict food intake to prevent serious obesity. Interestingly, in practice, problems with obesity are rarely seen, even when pigs are fed poorly timed diets similar to junk food, likely because swine diets are balanced for every nutrient. Indeed, feeding pigs diets deficient in micronutrients does trigger obesity. For humans, several micronutrient requirements have not been set officially, and diets optimized for all micronutrients are rarely provided. In conclusion, various obesity triggers are being debated for humans, which have been proven in swine. Obesity problems in pigs are nevertheless less excessive, likely because pigs recognize unhealthy eating practices and consequently reduce food intake to avoid serious complications. Finally, swine diets are normally balanced for all nutrients, which may be an important practice to prevent obesity, from which human health could greatly benefit.

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.

Fermentable fiber may increase endogenous losses of phosphorus (EPL) and amino acids (AA), thereby reducing nutrient digestibility. This study assessed effects of feeding increasing acacia gum with medium-to-high fermentability and low viscosity. Eight barrows cannulated at the terminal ileum were fed a control diet to measure basal endogenous P losses and three diets including 2.5%, 5.0%, or 7.5% acacia gum. Increasing acacia gum quadratically decreased diet ileal digestibility of dry matter (DM), gross energy (GE), linearly decreased diet total tract digestibility of DM, crude protein (CP), GE, and linearly increased hindgut fermentation of DM and GE. Increasing acacia gum linearly increased total tract endogenous P losses. Increasing acacia gum linearly decreased diet total tract digestibility of P, and standardized total tract digestibility of P calculated based on the calculated endogenous P losses or table values (NRC, 2012; 190 mg P/kg DMI). In conclusion, increasing dietary fermentable, low-viscous acacia gum decreased diet ileal and total tract digestibility of DM and GE, but did not affect ileal digestibility of CP and most AA. Increasing acacia gum inclusion reduced total tract digestibility of P, which might have been due to increased specific endogenous losses of P in the total tract of growing 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.

Oat ß-glucan and dietary calcium and phosphorus differentially modify intestinal expression of proinflammatory cytokines and monocarboxylate transporter 1 and cecal morphology in weaned pigs.

Physiologic effects of dietary oat ß-glucan and low and high dietary calcium-phosphorus (CaP) on intestinal morphology and gene expression related to SCFA absorption, mucus production, inflammation, and peptide digestion have not been established in weaned mammals. We therefore randomized 32 weaned pigs into 4 equal groups that received a cornstarch-casein-based diet with low (65% of the Ca and P requirement) and high (125 and 115% of the Ca and P requirement, respectively) CaP levels and low- and high-CaP diets supplemented with 8.95% oat ß-glucan concentrate for 14 d. High-CaP diets downregulated duodenal expression of IL-1ß (P < 0.05) by 30% compared with low-CaP diets. Furthermore, high-CaP diets reduced (P < 0.05) cecal crypt depth by 14% compared with low-CaP diets. Dietary ß-glucan upregulated the expression of cecal MCT1 (P < 0.05) by 40% and that of colonic IL-6 (P < 0.05) by 142% compared with the control diet. Correlation analysis indicated that cecal MCT1 (r = 0.99, P < 0.001) and colonic IL-6 (r = 0.84, P < 0.05) expression was positively related to luminal butyrate and total SCFA, respectively, indicating that ß-glucan may partly modify gene expression via increased SCFA generation. In conclusion, ß-glucan and CaP levels modulated the expression of selected genes and morphology in the postweaning period, but effects were specific to intestinal segment. The present results further indicate that, in addition to being essential nutrients for bone accretion, dietary CaP level may modify the intestinal tissue response in young pigs.

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, five faba bean cultivars including three zero-tannin, high vicine and covicine cultivars (Snowbird, Snowdrop, Tabasco), and two 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 phases 1 and 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 (<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 < 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 < 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 < 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 0-28), daily feed disappearance and weight gain for pigs fed Fabelle were 10% greater (P < 0.05) than those fed Malik; pigs fed zero-tannin cultivar diets were intermediate. Pigs fed Fabelle were 1.6 kg heavier (P < 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.

Cereal grain fiber composition modifies phosphorus digestibility in grower pigs.

Increased fermentable carbohydrates (e.g., ß-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, seven ileal-cannulated barrows (initial BW, 27.7 kg) were fed diets containing 80% of one of five cereal grains differing in amylose, ß-glucan, and fiber content: 1) high-fermentable, high-ß-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, Canadian Western 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% ß-glucan, 0.81% to 0.89% total P, and 0.19% to 0.35% InsP6-P. The MFB, LFB, and LFW had greater (P < 0.05) diet AID of P than HFB and HFA, and MFB had greater (P < 0.05) diet ATTD and STTD of P than HFB. The ATTD of InsP6-P was greater (P < 0.05) for HFB than LFB and the ATTD of the sum InsP6-2-P was greater (P < 0.05) for HFB and HFA than LFB. Total tract P release was greater (P < 0.001) for HFB, HFA, and LFW than MFB and LFB. The LFW had greater (P < 0.05) ATTD of Ca than LFB. Diet ß-glucan content was not correlated with STTD of P (R2 = 0.03) or ATTD of InsP6 (R2 = 0.05). In conclusion, cereal grains high in fermentable fiber, e.g., amylose and ß-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.

Increased fermentable carbohydrates (e.g., ß-glucan, amylose) may increase intestinal endogenous phosphorus (P) losses and thereby reduce P digestibility. The study assessed effects of cereal grains varying in fermentable carbohydrates on non-phytate-P and phytate-P. Phytate is the major binding form of P in plant seed and is incompletely degraded. Seven barrows cannulated at the terminal ileum were fed diets containing 80% of one of five cereal grains: 1) high-fermentable, high-ß-glucan, hull-less barley; 2) high-fermentable, high-amylose, hull-less barley; 3) moderate-fermentable, hull-less barley; 4) low-fermentable, hulled barley; and 5) low-fermentable wheat. Diet ileal digestibility of P was greater for low- and moderate-fermentable grain than high-fermentable grain, and diet total tract digestibility of P was greater for moderate-fermentable barley than high ß-glucan barley. Total tract digestibility of phytate-P was greater for high ß-glucan than low-fermentable barley. Total tract P release was greater for high-fermentable barley, and wheat than moderate- and low-fermentable barley. In conclusion, cereal grains high in fermentable fiber had lower diet ileal and total tract digestibility of P resulting in greater excretion of P, but greater total tract digestibility of phytate-P. Carbohydrate fermentation, thus, increases total tract P release from phytate-P degradation.

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.

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, ß-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.

Feeding weaned pigs diets containing benzoic acid or supplemental enzymes for 21 d after weaning changed the gut microbiota and metabolome. Benzoic acid increased feed intake, weight gain, and the presence of 1,2-propanediol in cecal digesta, which is an important microbial cross-feeding product. Dietary enzymes altered microbiota composition, increasing the presence of fiber-fermenting microbes including Prevotellaceae. Pigs fed a combination of both benzoic acid and enzymes showed improved resolution of postweaning diarrhea. These differences demonstrate the role of these feed additives in the establishment of gut microbes and metabolic pathways for the degradation of complex dietary components in the weaned pig. This study provides new information about alterations in microbial function and community composition using microbiota sequencing and metabolomic analysis.

Starch with high amylose and low in vitro digestibility increases short-chain fatty acid absorption, reduces peak insulin secretion, and modulates incretin secretion in pigs.

Diets containing different starch types affect peripheral glucose and insulin responses. However, the role of starch chemistry in kinetics of nutrient absorption and insulin and incretin secretion is poorly understood. Four portal vein-catheterized pigs (35.0 ± 0.2 kg body weight) consumed 4 diets containing 70% purified starch [0-63.2% amylose content and 0.22 (slowly) to 1.06%/min (rapidly) maximum rate of in vitro digestion] for 7-d periods in a 4 × 4 Latin square. On d 7, blood was collected for 12 h postprandial with simultaneous blood flow measurement for determining the net portal appearance (NPA) of nutrients and hormones. The NPA of glucose, insulin, C-peptide, and glucose-dependent insulinotropic polypeptide (GIP) during 0-4 h postprandial were lower (P < 0.05) and those of butyrate and total SCFA were higher (P < 0.05) when pigs consumed the diet containing slowly digestible compared with rapidly digestible starch. The peak NPA of insulin occurred prior to that of glucose when pigs consumed diets containing rapidly digestible starch. The kinetics of insulin secretion had a linear positive relation with kinetics of NPA of glucose (R(2) = 0.50; P < 0.01). In conclusion, starch with high amylose and low in vitro digestibility decreases the kinetics of glucose absorption and insulin and GIP secretion and increases SCFA absorption and glucagon-like peptide-1 secretion. In conclusion, starch with high amylose content and a lower rate and extent of in vitro digestion decreased glucose absorption and insulin secretion and increased SCFA absorption.

Starch with high amylose content and low in vitro digestibility increases intestinal nutrient flow and microbial fermentation and selectively promotes bifidobacteria in pigs.

Diets containing different starch types can affect enzymatic digestion of starch and thereby starch availability for microbial fermentation in the gut. However, the role of starch chemistry in nutrient digestion and flow and microbial profile has been poorly explained. Eight ileal-cannulated pigs (29.4 ± 0.9 kg body weight) were fed 4 diets containing 70% purified starch (amylose content, <5, 20, 28, and 63%; reflected by in vitro maximal digestion rate; 1.06, 0.73, 0.38, and 0.22%/min, respectively) in a replicated 4 × 4 Latin square. Ileal and fecal starch output, postileal crude protein yield, fecal total SCFA and total butyrate content, and gene copies of Bifidobacterium spp. in feces were higher (P < 0.05) when pigs consumed the slowly digestible starch diet than the remaining 3 starch diets. The in vitro starch digestion rate had a negative, nonlinear relationship with ileal starch flow (R(2) = 0.98; P < 0.001). Ileal starch flow was positively related to Bifidobacterium spp. (R(2) = 0.27; P < 0.01), Lactobacillus group (R(2) = 0.22; P < 0.01), and total butyrate content (R(2) = 0.46; P < 0.01) but was not related to Enterobacteriaceae (R(2) < 0.00; P = 0.92). In conclusion, starch with high amylose content and low in vitro digestibility increased postileal nutrient flow and microbial fermentation and selectively promoted Bifidobacterium spp. in the distal gut.