Gut microbiota plays an important role in the health and performance of the host. Characterizations of gut microbiota, core microbiomes, and microbial networks in different chicken breeds are expected to provide clues for pathogen exclusion, improving performance or feed efficiency. Here, we characterized the gut microbiota of “finishing” chickens (at the end of production life) of indigenous Indian Nicobari, Ghagus, and Aseel breeds, originating from the Nicobari island, coastal India, and the Indian mainland, respectively, as well as a global commercial broiler line, VenCobb 400, using 16S rDNA amplicon sequencing. We found that diversity, as well as richness of microbiota, was higher in indigenous breeds than in the broiler line. Beta diversity analysis indicated the highest overlap between Ghagus and Nicobari breeds and a very low overlap between the broiler line and all indigenous breeds. Linear discriminant analysis effect size (LEfSe) revealed 82 breed- or line-specific phylotype operational taxonomic unit (OTU) level biomarkers. We confirm the presence of breed specific and across-breed core microbiomes. Additionally, we show the existence of breed specific complex microbial networks in all groups. This study provides the first (and comprehensive) insight into the gut microbiota of three indigenous breeds and one commercial broiler line of chickens reared without antimicrobials, and underscores the need to study microbial diversity in other indigenous breeds.

The present study was conducted to evaluate the effect of tea (Camellia sinensis) seed saponins (TSS) on in vitro rumen fermentation with different forage to concentrate ratios in the in vitro gas production technique. Experimental treatments were a low forage diet (forage: concentrate = 30:70), a medium forage diet (forage: concentrate = 50:50) and a high forage diet (forage: concentrate = 70:30). TSS was added at levels of 0.0%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% and 1.0% of substrate. Protozoal count, ammonia-N production and methane production decreased linearly up to the dose level of 0.8% in all the substrates. The maximum reduction obtained was 54.6%, 57.2% and 60.6% for protozoal counts; 29%, 33% and 36% for methane production; and 36.6%, 36.6% and 33.8% for ammonia-N production at low, medium and high forage diets, respectively. Net 24 h gas production, short chain fatty acid production, metabolizable energy value increased and in vitro true dry matter and organic matter digestibility significantly decreased due to addition of saponins. Results suggest that TSS has the potential to reduce methane production and positively impact rumen fermentation across different forage to concentrate ratios.