Influence of particle size and multi-enzyme supplementation of fibrous diets on total tract digestibility and performance of weaning (8–20kg) and growing (20–40kg) pigs

Monomodular and multifunctional processive endocellulases: implications for swine nutrition and gut microbiome

Poor efficiency of dietary fibre utilization not only limits global pork production profit margin but also adversely affects utilization of various dietary nutrients. Poor efficiency of dietary nutrient utilization further leads to excessive excretion of swine manure nutrients and results in environmental impacts of emission of major greenhouse gases (GHG), odor, nitrate leaching and surface-water eutrophication. Emission of the major GHG from intensive pork production contributes to global warming and deteriorates heat stress to pigs in tropical and sub-tropical swine production. Exogenous fibre enzymes of various microbial cellulases, hemicellulases and pectinases have been well studied and used in swine production as the non-nutritive gut modifier feed enzyme additives in the past over two decades. These research efforts have aimed to improve growth performance, nutrient utilization, intestinal fermentation as well as gut physiology, microbiome and health via complementing the porcine gut symbiotic microbial fibrolytic activities towards dietary fibre degradation. The widely reported exogenous fibre enzymes include the singular use of respective cellulases, hemicellulases and pectinases as well as their multienzyme cocktails. The currently applied exogenous fibre enzymes are largely limited by their inconsistent in vivo efficacy likely due to their less defined enzyme stability and limited biochemical property. More recently characterized monomodular, multifunctional and processive endoglucanases have the potential to be more efficaciously used as the next-generation designer fibre biocatalysts. These newly emerging multifunctional and processive endoglucanases have the potential to unleash dietary fibre sugar constituents as metabolic fuels and prebiotics, to optimize gut microbiome, to maintain gut permeability and to enhance performance in pigs under a challenged environment as well as to parallelly unlock biomass to manufacture biofuels and biomaterials.

Effects of fibre-degrading enzymes in combination with different fibre sources on ileal and total tract nutrient digestibility and fermentation products in pigs

The study was conducted to determine effects of a complex of fibre-degrading enzymes (xylanase, cellulase and β-glucanase) on nutrient digestibility, fibre fermentation and concentrations of short chain fatty acids (SCFA) at different parts of digestive tract in pigs fed different fibre-rich ingredients. A total of 36 barrows fitted with T-cannulas in the distal ileum (initial body weight of 41.1 ± 2.7 kg) were randomly allotted to six dietary treatments with three different high-fibre diets including maize bran (MB), sugar beet pulp (SBP) and soybean hulls (SH) with or without supplementation of fibre-degrading enzymes. Enzyme supplementation improved (p < 0.05) apparent ileal digestibility (AID) of dietary gross energy (GE), crude protein, dry matter (DM), organic matter (OM), total dietary fibre (TDF), neutral detergent fibre (NDF) and apparent total tract digestibility (ATTD) of dietary GE, DM, OM, TDF, insoluble dietary fibre (IDF) when pigs were fed MB, SBP or SH diets. When compared to the SBP and SH diets, the AID of GE, DM, ash, OM and NDF in diet MB was higher (p < 0.05), but the hindgut disappearance and ATTD of nutrients, except for ether extract and crude ash, were lower (p < 0.05). Enzyme supplementation increased acetate and total SCFA concentrations in ileal digesta and faeces of pigs. In conclusion, enzyme addition improved IDF fermentation and SCFA concentration in the whole intestine of pigs, and there was a large variation of digestibility of fibre components among MB, SH and SBP owing to their different fibre composition. Therefore, fibre-degrading enzymes should be applied to fibrous diets to improve efficient production of swine, especially considering low fibre digestibility of fibre-rich ingredients.

Dietary protease improves growth rate and protein digestibility of growing-finishing pigs

This research was performed to investigate the hypothesis that dietary mono-component protease (PRO) might improve growth performance, nutrient digestibility, and carcass characteristics of growing-finishing pigs. A total of eighty-four pigs [Duroc × (Landrace × Yorkshire), 25.3 ± 2.16 kg initial body weight] were randomly assigned to three dietary treatments (7 replicates/treatment; 2 barrows and 2 gilts/replicate) in a randomized complete block design (block = sex). The dietary treatments were prepared as follows; (1) a positive control (PC) as a typical growing-finishing diet based on corn and soybean meal, (2) PC added with 0.015% of PRO (PCPRO), and (3) a negative control (NC) added with 0.015% of PRO (NCPRO). The NC had a lower concentration of crude protein (CP) compared with PC. The PRO was a commercial product that contained 75,000 protease units/g and derived from Nocardiopsis prasina produced in Bacillus licheniformis. Dietary treatments were offered to pigs during growing and finishing periods. Measurements were growth performance, apparent total tract digestibility (ATTD) of nutrients, and carcass characteristics. The PCPRO and/or NCPRO increased average daily gain (ADG) and gain to feed ratio (G:F) during growing (p < 0.10), finishing (p < 0.05), and growing-finishing periods (p < 0.10) compared with PC. Furthermore, pigs fed PCPRO and NCPRO had higher (p < 0.05) ATTD of CP and energy during growing and/or finishing periods than those fed PC. In conclusion, the supplementation of PRO in diets improved growth performance and protein digestibility of growing-finishing pigs.

Effect of increasing inclusion rates of tofu by-product in diets of growing pigs on nitrogen balance and ammonia emission from manure

To reduce competition with human-edible feed resources, it is of interest to incorporate by-products from the food industry in animal feeds. The current research investigated the effect of including increasing amounts of tofu by-product (TF) in practical pig diets on animal performance, nitrogen balance and ammonia emissions from manure. Two experiments were conducted including a control diet without TF, containing 160 g/kg dietary non-starch polysaccharides (NSPs) and three diets including 122, 246 and 360 g TF/kg DM (TF122, TF246 and TF360, respectively) to reach 220, 280 and 360 g/kg NSP. All diets had the same level of CP and protein digestible in the small intestine which particularly was realized by replacing rice bran with TF. Animal performance was assessed in a first experiment with 40 growing barrows with initial BW of 26.6 ± 1.80 kg (M ± SD) being allocated to the 4 treatments, during 2 growth phases (i.e. until 50 kg BW and from 50 to 80 kg BW). In the growth phase until 50 kg, feed intake and average daily gain (ADG) were linearly reduced by dietary TF inclusion, while this negative impact disappeared during the second growth phase (50 to 80 kg BW). Tofu by-product inclusion even positively affected the feed conversion ratio during this second growth phase (3.4 to 2.7 kg feed/kg ADG for 0 to 360 g/kg dietary TF). Over the entire growth period, performance and feed intake were negatively affected at the highest dietary TF level. Experiment 2 was conducted to assess digestibility, nitrogen balance and ammonia emission from manure. For this purpose, 16 pigs with BW of 62.8 ± 3.6 kg (M ± SD) were assigned to either 1 of the 4 treatments. There was no difference in total tract apparent digestibility of dietary organic matter or CP, while NDF digestibility increased with increasing TF level, suggesting increasing importance of the hindgut fermentation when digesting diets with increasing TF levels. Nevertheless, this was not reflected in increasing levels of faecal volatile fatty acids or purines, nor in reduced manure pH. As a result, ammonia emission from slurry was not reduced through dietary TF inclusion, despite the linear decrease in urinary nitrogen. In conclusion, TF can be included in pigs' diets up to an inclusion rate of 25% without risk of impaired animal performance; however, this dietary strategy fails to mitigate ammonia emission from slurry.

Dietary protein level affects nutrient digestibility and ileal microbiota structure in growing pigs

This study aimed to determine whether dietary protein content influences pig health as indicated by ileal microbiota structure and coefficients of total tract apparent digestibility (CTTAD) of nutrients. Seventy-two gilts, with an initial body weight of 29.9 ± 1.5 kg, were used in this 42-day feeding study. Pigs were randomly allotted to one of three dietary treatments of corn-soybean meal contained 14, 16 or 18% crude protein (CP). As dietary CP content decreased, the CTTAD of most essential amino acids (AAs), except for arginine and histidine, increased linearly, while those of most nonessential AAs decreased linearly. The concentration of total short-chain fatty acids (SCFA) was higher in pigs fed the diet with 14% CP content than others. Ileal microbiota structure was changed by dietary treatments. In particular, at the phylum level, the relative abundance of Tenericutes in ileal digesta decreased as the dietary protein content reduced, while that of cyanobacteria increased. At the genus level, the relative abundance of Weeksella, Phaseolus acutifolius, Slackia, Sulfurimonas and Aerococcus showed significant differences among the three dietary treatments. In conclusion, ileal microbiota structure was changed by dietary protein content. Moderate reduction of protein intake can benefit gut health by enhancing the gut microbial fermentation and SCFA formation.

Influences of quorum-quenching probiotic bacteria on the gut microbial community and immune function in weaning pigs

The aim of this study is to investigate the dynamic gut microbial diversity in weaning swine after administering feed supplemented with probiotic bacteria that specifically inhibit the activity of quorum molecules. Initially, the universal quorum molecule autoinducer-2 (AI-2) bioassay results indicated that AI-2 activity was profoundly inhibited in enterohemorrhagic Escherichia coli (EHEC) O157:H7 in the presence of Lactobacillus acidophilus strain 30SC cell extract, although the growth of EHEC was not affected. Based on plate counting results, bacterial community analysis revealed a specific reduction in coliforms compared to the control, whereas the population of lactobacilli increased in weaning swine in in vivo trials. Supplementation with L. acidophilus strain 30SC did not affect the counts of other communities, such as total aerobes and yeast/mold. In addition, PCR-denaturing gradient gel electrophoresis analysis showed a significant difference in the 16S rRNA gene products after administering L. acidophilus strain 30SC. Selected bands were sequenced, and most of them were identified as uncultured bacterium clones or a Lactobacillus- and Bifidobacterium-specific community. Therefore, our results indicate that quorum-quenching probiotic bacteria can significantly modulate the gut microbiota of swine and these beneficial effects can contribute to the improvement of performance and health in the gastrointestinal tract of weaning pigs.

Effect of dietary supplementation with protease on growth performance, nutrient digestibility, intestinal morphology, digestive enzymes and gene expression of weaned piglets

This study was conducted to investigate the effect of dietary protease supplementation on the growth performance, nutrient digestibility, intestinal morphology, digestive enzymes and gene expression in weaned piglets. A total of 300 weaned piglets (21 days of age Duroc × Large White × Landrace; initial BW = 6.27 ± 0.45 kg) were randomly divided into 5 groups. The 5 diets were: 1) positive control diet (PC), 2) negative control diet (NC), and 3) protease supplementations, which were 100, 200, and 300 mg per kg NC diet. Results indicated that final BW, ADG, ADFI, crude protein digestibility, enzyme activities of stomach pepsin, pancreatic amylase and trypsin, plasma total protein, and intestinal villus height were higher for the PC diet and the supplementations of 200 and 300 mg protease per kg NC diet than for the NC diet (P < 0.05). Supplementations of 200 and 300 mg protease per kg NC diet significantly increased the ratio of villus height to crypt depth (VH:CD) of duodenum, jejunum and ileum compared with NC diet (P < 0.05). Feed to gain ratio, diarrhea index, blood urea nitrogen, and diamine oxidase were lower for the PC diet and supplementations of 200 and 300 mg protease per kg NC diet than for the NC diet (P < 0.05). Piglets fed the PC diet had a higher peptide transporter 1 (PepT1) mRNA abundance in duodenum than piglets fed the NC diet (P < 0.05), and supplementations of 100, 200 and 300 mg protease per kg NC diet increased the PepT1 mRNA abundance in duodenum (P < 0.05) comparing with the NC diet. Piglets fed the PC diet had a higher b0,+AT mRNA abundance in jejunum than piglets fed the NC diet (P < 0.05), and supplementations of 200 and 300 mg protease per kg NC diet increased the b0,+AT mRNA abundance in jejunum and ileum comparing with the NC diet (P < 0.05). In summary, dietary protease supplementation increases growth performance in weaned piglets, which may contribute to the improvement of intestinal development, protein digestibility, nutrient transport efficiency, and health status of piglets when fed low digestible protein sources.

Effects of dietary supplementation of multi-enzyme on growth performance, nutrient digestibility, small intestinal digestive enzyme activities, and large intestinal selected microbiota in weanling pigs

Two experiments were conducted to assess the effects of dietary supplementation of an exogenous multi-enzyme (EME) preparation to 35- to 65-d-old piglets on apparent total tract digestibility (ATTD), growth performance, digestive enzyme activities, and selected microbial populations in feces. In Exp.1, twenty eight 35-d-old piglets were randomly assigned to 7 dietary treatments (corn-soybean based diet supplemented with 0, 100, 150, 200, 250, 300, or 350 mg EME/kg) in a 14-d digestibility study. Piglets fed the diets supplemented with EME had greater ATTD of DM, CP, and GE (P = 0.001, 0.005, and 0.009, respectively) than those fed the diet without EME supplementation, and those ATTD values increased linearly and quadratically (P < 0.001) as the levels of supplemented EME increased. In Exp. 2, two hundred 35-d-old weanling piglets were randomly allocated to 20 pens. The pens were then randomly assigned to 5 dietary treatments (corn-soybean based diet supplemented with 0, 100, 150, 250, or 350 mg EME/kg) with 4 pens per treatment in a 30-d feeding experiment. Piglets has ad libitum access to diets and water, and they were weighed at the beginning (35-d-old), middle (50-d-old), and end (65-d-old) of the experiment. Fecal samples were grabbed directly from the rectum and digesta samples from duodenum, jejunum, and ileum were taken at the end of the experiment for the analysis of selected bacteria populations and digestive-enzyme activities. The ADG and ADFI tended to be greater with the increasing levels of supplemented EME in both periods, whereas G:F was improved (P = 0.012 and 0.017) by EME in the period of 35 to 50 d of age and during the overall experimental period. Furthermore, inclusion of EME in diet increased the counts of Lactobacilli spp. and Bacillus subtilis spp., but reduced the populations of Salmonella spp. and Escherichia coli spp. in the feces. The EME supplementation also enhanced (P < 0.05) the activities of amylase, lipase, and protease in the small intestine. The growth performance-enhancing effects of EME appeared to be mediated by the age of the piglet and the dose of EME used. Supplementation of corn-soybean meal diets for 35- to 65-d-old piglets with EME has a potential to enhance gut health condition, increase nutrient digestion, and increase growth performance.

Fiber effects in nutrition and gut health in pigs

Dietary fiber is associated with impaired nutrient utilization and reduced net energy values. However, fiber has to be included in the diet to maintain normal physiological functions in the digestive tract. Moreover, the negative impact of dietary fiber will be determined by the fiber properties and may differ considerably between fiber sources. Various techniques can be applied to enhance nutritional value and utilization of available feed resources. In addition, the extent of fiber utilization is affected by the age of the pig and the pig breed. The use of potential prebiotic effects of dietary fiber is an attractive way to stimulate gut health and thereby minimize the use of anti-microbial growth promoters. Inclusion of soluble non-starch polysaccharides (NSP) in the diet can stimulate the growth of commensal gut microbes. Inclusion of NSP from chicory results in changes in gut micro-environment and gut morphology of pigs, while growth performance remains unaffected and digestibility was only marginally reduced. The fermentation products and pH in digesta responded to diet type and were correlated with shifts in the microbiota. Interestingly, fiber intake will have an impact on the expression of intestinal epithelial heat-shock proteins in the pig. Heat-shock proteins have an important physiological role in the gut and carry out crucial housekeeping functions in order to maintain the mucosal barrier integrity. Thus, there are increasing evidence showing that fiber can have prebiotic effects in pigs due to interactions with the gut micro-environment and the gut associated immune system.