Caecum odd‐numbered and branched‐chain fatty acid composition in response to dietary changes in fattening rabbits

Abstract

The study aimed to describe the interactions between nutrition and caecal bacteria abundance using odd-numbered and branched-chain fatty acids (OBCFA). Following a 2 × 2 factorial design, 47 rabbits were fed diets with two levels of digestible fibre (DF, 180 vs. 260 g/kg DM) supplemented with soybean oil (SO, 20 g/kg) or not. At 77 days of age, fatty acid (FA) composition was determined in caecal contents. The microbial origin of OBCFA vs. dietary FA in caecal contents was illustrated by clustering of these FA in the loading plots of principal component analysis. The contribution of odd-numbered FA in the OBCFA pattern was increased (p < 0.05) for high DF diets, whereas that of branched-chain FA decreased (p < 0.05), indicating potential shifts in the relative abundance of Gram-negative and Gram-positive fibrolytic bacteria respectively. Soybean oil reduced the relative importance of OBCFA (p < 0.001) in total microbial FA; however, its effects appeared to depend on the readily available fermentable substrate, as indicated by the DF × SO interactions (p < 0.001). In conclusion, OBCFA may be potentially used as markers of caecum function, but further detailed studies are necessary to validate their use as diagnostic tools in rabbit nutrition.

Both Dietary Fatty Acids and Those Present in the Cecotrophs Contribute to the Distinctive Chemical Characteristics of New Zealand Rabbit Milk Fat

“…However, in rabbits it is not known which bacteria are involved in CLA production. Some microorganisms that metabolize FA have been detected in rabbit feces, such as Bacteroides (Papadomichelakis et al, ) and Staphylococcus (Comi and Cantoni, ). In humans, it has been observed that Lactobacillus , Bifidobacterium , Propionibacterium , Eubacterium , Roseburia , and Butyrivibrio are involved in the production of CLA isomers in the large intestine (Devillard et al, ).…”

“…Bacteria in the cecum of rabbits play an important role in the production of protein (Belenguer et al, ), vitamins (Hörnicke, ), and volatile FA (Amici et al, ; Xiccato et al, ). Bacteria in the cecum also modify FA and contribute to PUFA synthesis from the dietary intake of linoleic and linolenic acids (Amici et al, ; Bauman et al, ; Papadomichelakis et al, ). In ruminants, the microorganisms that metabolize FA include Ruminococcus , Fusocillus , and Anaerovibrio (Hobson and Stewart, ); Propionobacterium can produce CLA trans ‐10, cis ‐12 (Castillo et al, ), whereas Butyrivibrio can produce CLA cis ‐9, trans ‐11 (Wallace et al, ).…”