Effects of Cashew Nut Shell Liquid on Hindgut Fermentation and Microbiota of Chickens

Cashew nut shell liquid (CNSL), a feed additive for chickens, was evaluated for its influence on the hindgut environment by determining fermentation and bacterial profiles using cecal contents, fecal slurry and pure cultures. A farm-scale study showed that CNSL feeding to broiler chickens from 0 to 42 days of age improved body weight gain and lowered mortality. Cecal levels of short chain fatty acids increased with CNSL feeding, while ammonia and indole levels decreased. Feeding CNSL decreased the relative abundance of cecal bacteria belonging to some clostridial groups and Ruminococcaceae. In particular, Clostridium perfringens was undetectable following CNSL feeding. A pure culture study showed that CNSL (≥ 6.25 μg/ml) inhibited C. perfringens growth, accompanied by cell surface disruption based on electron microscopic observation. Fermentation profiles of slurry cultures prepared from feces of chickens were altered by CNSL supplementation toward less ammonia production. The lowered ammonia was correlated positively with the abundance of unclassified Lachnospiraceae and unclassified Ruminococcaceae, and negatively with unclassified Enterobacteriaceae and Sutterella. These results suggest that CNSL could exert its beneficial influence on the hindgut health of chickens through impacting the microbiota.