Intestinal gene expression in pigs: effects of reduced feed intake during weaning and potential impact of dietary components

The weaning transition is characterised by morphological, histological and microbial changes, often leading to weaning-associated disorders. These intestinal changes can partly be ascribed to the lack of luminal nutrition arising from the reduced feed intake common in pigs after weaning. It is increasingly becoming clear that changes in the supply with enteral nutrients may have major impacts on intestinal gene expression. Furthermore, the major dietary constituents, i.e. carbohydrates, fatty acids and amino acids, participate in the regulation of intestinal gene expression. However, nutrients may also escape digestion by mammalian enzymes in the upper gastrointestinal tract. These nutrients can be used by the microflora, resulting in the production of bacterial metabolites, for example, SCFA, which may affect intestinal gene expression indirectly. The present review provides an insight on possible effects of reduced feed intake on intestinal gene expression, as it may occur post-weaning. Detailed knowledge on effects of reduced feed intake on intestinal gene expression may help to understand weaning-associated intestinal dysfunctions and diseases. Examples are given of intestinal genes which may be altered in their expression due to supply with specific nutrients. In that way, gene expression could be modulated by dietary means, thereby acting as a potential therapeutic tool. This could be achieved, for example, by influencing genes coding for digestive or absorptive proteins, thus optimising digestive function and metabolism, but also with regard to immune response, or by influencing proliferative processes, thereby enhancing mucosal repair. This would be of special interest when designing a diet to overcome weaning-associated problem

Differences in intestinal size, structure, and function contributing to feed efficiency in broiler chickens reared at geographically distant locations

peer-reviewedThe contribution of the intestinal tract to differences in residual feed intake (RFI) has been inconclusively studied in chickens so far. It is also not clear if RFI-related differences in intestinal function are similar in chickens raised in different environments. The objective was to investigate differences in nutrient retention, visceral organ size, intestinal morphology, jejunal permeability and expression of genes related to barrier function, and innate immune response in chickens of diverging RFI raised at 2 locations (L1: Austria; L2: UK). The experimental protocol was similar, and the same dietary formulation was fed at the 2 locations. Individual BW and feed intake (FI) of chickens (Cobb 500FF) were recorded from d 7 of life. At 5 wk of life, chickens (L1, n = 157; L2 = 192) were ranked according to their RFI, and low, medium, and high RFI chickens were selected (n = 9/RFI group, sex, and location). RFI values were similar between locations within the same RFI group and increased by 446 and 464 g from low to high RFI in females and males, respectively. Location, but not RFI rank, affected growth, nutrient retention, size of the intestine, and jejunal disaccharidase activity. Chickens from L2 had lower total body weight gain and mucosal enzyme activity but higher nutrient retention and longer intestines than chickens at L1. Parameters determined only at L1 showed increased crypt depth in the duodenum and jejunum and enhanced paracellular permeability in low vs. high RFI females. Jejunal expression of IL1B was lower in low vs. high RFI females at L2, whereas that of TLR4 at L1 and MCT1 at both locations was higher in low vs. high RFI males. Correlation analysis between intestinal parameters and feed efficiency metrics indicated that feed conversion ratio was more correlated to intestinal size and function than was RFI. In conclusion, the rearing environment greatly affected intestinal size and function, thereby contributing to the variation in chicken RFI observed across locations

Assessing the effect of dietary inulin supplementation on gastrointestinal fermentation, digestibility and growth in pigs: A meta-analysis

International audienceInulin has been reported to improve the homeostasis in the gastrointestinal tract (GIT) of pigs by modulating the intestinal microbiota and fermentation. The present study aimed to quantify the relationship between dietary inulin and microbial response variables in digesta from the GIT and feces of weaned, growing and finishing pigs using a meta-analytical approach. We further examined the effect of dietary inulin on the coefficients of ileal (CLAD) and total tract apparent digestibility (CTTAD) of nutrients and ADG. Pig's starting body weight was considered the main inclusion criterion. Missing information about explanatory variables and few values available for response variables reduced the number of studies included. From the 33 included articles published between 2000 and 2016, individual sub-datasets for fermentation metabolites, bacterial abundances, CIAD, CTTAD and performance were built. Prediction models on the effect on inulin were computed accounting for inter- and intra-study variability. Dietary inulin levels ranged from 0.1 to 25.8%, whereby the median and mean inulin levels were 0.1-2% and 3-4%, respectively. Few of the investigated fermentation response variables were influenced by dietary inulin. Strong negative relationships were found between dietary inulin and gastric pH in weaned pigs (R-2 = 0.81; P < 0.001; n = 12), colonic enterobacteria (R-2 = 0.50; P < 0.001; n = 19) and fecal lactobacilli (R-2 = 0.41; P < 0.001; n = 26) throughout all production phases, whereas observed negative relationships between inulin and colonic bifidobacteria and fecal enterobacteria and Escherichia coli were of minor physiological relevance (P < 0.05). Moreover, increasing inulin levels negatively correlated with the CTTAD of crude protein (R-2 = 0.83; P < 0.001; n = 15), but they did not influence average daily gain of pigs. Best-fit models indicated that dietary crude protein amplified the effect of inulin on CTTAD of crude protein and gastric pH, but counteracted the inulin effect on fecal E. coli (P < 0.05). Accordingly, both pig's body weight and inulin decreased gastric pH and fecal lactobacilli but counteracted the inulin effect on colonic bifidobacteria and fecal E. coli (P < 0.05). In conclusion, this study supported a stimulatory effect of dietary inulin on gastric acid secretion, which may be favorable GIT health in weaned pigs. However, due to limiting information provided in the original studies, like dietary fructans or fibers, low numbers of observation and low inulin levels, relationships should be regarded as trends

Assessing the effect of dietary inulin supplementation on gastrointestinal fermentation, digestibility and growth in pigs: A meta-analysis

Inulin has been reported to improve the homeostasis in the gastrointestinal tract (GIT) of pigs by modulating the intestinal microbiota and fermentation. The present study aimed to quantify the relationship between dietary inulin and microbial response variables in digesta from the GIT and feces of weaned, growing and finishing pigs using a meta-analytical approach. We further examined the effect of dietary inulin on the coefficients of ileal (CIAD) and total tract apparent digestibility (CTTAD) of nutrients and ADG. Pig's starting body weight was considered the main inclusion criterion. Missing information about explanatory variables and few values available for response variables reduced the number of studies included. From the 33 included articles published between 2000 and 2016, individual sub-datasets for fermentation metabolites, bacterial abundances, CIAD, CTTAD and performance were built. Prediction models on the effect on inulin were computed accounting for inter- and intra-study variability. Dietary inulin levels ranged from 0.1 to 25.8%, whereby the median and mean inulin levels were 0.1\ue2\u80\u932% and 3\ue2\u80\u934%, respectively. Few of the investigated fermentation response variables were influenced by dietary inulin. Strong negative relationships were found between dietary inulin and gastric pH in weaned pigs (R2= 0.81; P < 0.001; n = 12), colonic enterobacteria (R2= 0.50; P < 0.001; n = 19) and fecal lactobacilli (R2= 0.41; P < 0.001; n = 26) throughout all production phases, whereas observed negative relationships between inulin and colonic bifidobacteria and fecal enterobacteria and Escherichia coli were of minor physiological relevance (P < 0.05). Moreover, increasing inulin levels negatively correlated with the CTTAD of crude protein (R2= 0.83; P < 0.001; n = 15), but they did not influence average daily gain of pigs. Best-fit models indicated that dietary crude protein amplified the effect of inulin on CTTAD of crude protein and gastric pH, but counteracted the inulin effect on fecal E. coli (P < 0.05). Accordingly, both pig's body weight and inulin decreased gastric pH and fecal lactobacilli but counteracted the inulin effect on colonic bifidobacteria and fecal E. coli (P < 0.05). In conclusion, this study supported a stimulatory effect of dietary inulin on gastric acid secretion, which may be favorable GIT health in weaned pigs. However, due to limiting information provided in the original studies, like dietary fructans or fibers, low numbers of observation and low inulin levels, relationships should be regarded as trends

Differences in intestinal size, structure, and function contributing to feed efficiency in broiler chickens reared at geographically distant locations

The contribution of the intestinal tract to differences in residual feed intake (RFI) has been inconclusively studied in chickens so far. It is also not clear if RFI-related differences in intestinal function are similar in chickens raised in different environments. The objective was to investigate differences in nutrient retention, visceral organ size, intestinal morphology, jejunal permeability and expression of genes related to barrier function, and innate immune response in chickens of diverging RFI raised at 2 locations (L1: Austria; L2: UK). The experimental protocol was similar, and the same dietary formulation was fed at the 2 locations. Individual BW and feed intake (FI) of chickens (Cobb 500FF) were recorded from d 7 of life. At 5 wk of life, chickens (L1, n = 157; L2 = 192) were ranked according to their RFI, and low, medium, and high RFI chickens were selected (n = 9/RFI group, sex, and location). RFI values were similar between locations within the same RFI group and increased by 446 and 464 g from low to high RFI in females and males, respectively. Location, but not RFI rank, affected growth, nutrient retention, size of the intestine, and jejunal disaccharidase activity. Chickens from L2 had lower total body weight gain and mucosal enzyme activity but higher nutrient retention and longer intestines than chickens at L1. Parameters determined only at L1 showed increased crypt depth in the duodenum and jejunum and enhanced paracellular permeability in low vs. high RFI females. Jejunal expression of IL1B was lower in low vs. high RFI females at L2, whereas that of TLR4 at L1 and MCT1 at both locations was higher in low vs. high RFI males. Correlation analysis between intestinal parameters and feed efficiency metrics indicated that feed conversion ratio was more correlated to intestinal size and function than was RFI. In conclusion, the rearing environment greatly affected intestinal size and function, thereby contributing to the variation in chicken RFI observed across locations