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

Abstract

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.

The biological effects of microencapsulated organic acids and botanicals induces tissue-specific and dose-dependent changes to the Gallus gallus microbiota

“…However, the blend of organic acids and botanicals used in the current study, produced an increase in diversity and evenness for the jejunum compared to the ileum. Similarly, in other pharmacological studies, the biotransformation of drugs by the microbiota results in their absorption in the jejunum and are linked to increased diversity and biological activity of the microbial population [41,42]. The jejunum is the main sight for nutrient absorption in poultry [38], as well as in mammals, and it has been suggested that the jejunum is the most logical site to observe treatment effects [13] which is what we observed in the current study.…”

“…Though not considered in those earlier studies, it is possible that changes to the GIT microbial populations while the bird is developing could have contributed to the observed decreases in Salmonella and Campylobacter colonization, but additional studies are required to con rm this hypothesis. Studies support there is compartmental activation of the microbiota; but ultimately it will be the resulting physiological effects within the different compartments as they carry out their speci c biological processes [42,52] that will have the greatest impact. While feed e ciency, nutrient absorption, enzymatic activity and other GIT health indicators were not measured in this study, future studies will determine if these parameters are directly impacted by the microbial population in each compartment of the GIT.…”

The biological effects of microencapsulated organic acids and botanicals induces tissue-specific and dose-dependent changes to the microbiota

“…Numerous microbiota studies have focused on the ceca, which may not be ideal as digestion also occurs in the foregut [18,19]. Evidence suggests that the jejunum of feed-efficient animals, which is the site of nutrient absorption, has improved morphology, and increased enzymatic activity [20]. Likewise, the ileum, which absorbs any remaining vitamins and other nutrients not absorbed in the jejunum, is lighter and longer in more feed-efficient animals, with improved morphology [20].…”

“…Evidence suggests that the jejunum of feed-efficient animals, which is the site of nutrient absorption, has improved morphology, and increased enzymatic activity [20]. Likewise, the ileum, which absorbs any remaining vitamins and other nutrients not absorbed in the jejunum, is lighter and longer in more feed-efficient animals, with improved morphology [20]. While the ceca are heavily focused on in other studies with natural compounds and for the microbiota responses, it may not necessarily be the site biological activity occurs nor the site with the most biological ramifications if the microbial populations change [16,17,20].…”

“…Likewise, the ileum, which absorbs any remaining vitamins and other nutrients not absorbed in the jejunum, is lighter and longer in more feed-efficient animals, with improved morphology [20]. While the ceca are heavily focused on in other studies with natural compounds and for the microbiota responses, it may not necessarily be the site biological activity occurs nor the site with the most biological ramifications if the microbial populations change [16,17,20]. Additionally, as microencapsulation technology continues to evolve, the targeted delivery of natural compounds through the harsh environment of the crop to their intended further location down the GIT may serve to improve biological activity [21].…”