Effects of dietary Greek oregano (Origanum vulgare ssp. hirtum) supplementation on rumen fermentation, enzyme profile and microbial communities in goats.

This study was conducted to examine in vivo long-term effects of dietary dried oregano (Origanum vulgare ssp. hirtum) whole plant on rumen fermentation, enzyme profile and microbial communities. For this purpose, eight healthy, adult, non-lactating Alpine goats were kept in tie stalls equipped for individual feeding and randomly divided into two homogeneous groups: one fed 0.6 kg of a concentrate mixture and 0.6 kg of wheat straw without any supplementation and served as control group (CON) while the other group (OR) fed the same diet of CON but supplemented with 20 g of dried oregano plants (OPs) to provide daily dosage of 1 ml of essential oil (EO) per animal. The experimental period lasted 69 days and individual rumen fluid samples were obtained every 2 weeks at 0 and 4 hr after feeding. The results showed that dietary supplementation with OPs increased the protease activity (p < .001) and ammonia concentration (p < .05) in the rumen. Among the studied microbial populations, Peptostreptococcus anaerobius (p = .028) and Clostridium sticklandii (p < .001) were found to be the most sensitive to oregano at the current dosage. Furthermore, the total methanogen population significantly decreased (p < .05). It is concluded that a long-term dietary administration of OPs can suppress specific rumen micro-organisms and modify rumen fermentation favourably at least by means of suppressing methanogens.

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

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.