ASSESSMENT OF RUMINAL METHANOGEN COMPOSITION AND METHANE EMISSION LEVELS IN CROSSBRED AND VECHUR COWS UNDER THE SAME DIETARY REGIMEN*

Abstract

The rumen microbial community plays a critical role in methane emission from ruminants. However, there is a lack of data comparing the composition of the rumen methanogenic community of cattle breeds of Kerala. Present study was undertaken with the objective of assessing rumen methanogen composition and methane emission levels of crossbred and Vechur cattle. All the animals were fed with ration of 50:50 (forage: concentrate) diet on dry matter basis for a period of three weeks. Rumen liquor and rumen gas samples were collected. DNA isolated from rumen liquor using standard procedure were pooled genetic group wise and subjected to whole metagenome sequencing and further bioinformatics analysis. The concentrations of methane (percentage) in gas samples were determined using a methane analyser. Research findings revealed that bacteria was the most dominant and archaea was the second prominent domain found in rumen of both genetic groups. Phylum Euryarchaeota of the domain Archaea constitute methanogens. At family level, Methanomassiliicoccaceae, Methanomicrobiaceae, Methanobacteriaceae were the predominant methanogens in crossbred and Vechur rumen. Population of specific methanogens were found to be significantly different between genetic groups. Biodiversity indices displayed higher richness, evenness and diversity for rumen methanogens in Vechur cows compared to crossbred. Comparative analysis of methane emission levels in crossbred and Vechur confirmed the effect of genetic group on methane emission from rumen.

Keywords

• rumen metagenome
• methane emission
• methanogen composition
• vechur cattle
• crossbred cattle