Rumen bacteria and feed efficiency of beef cattle fed diets with different protein content

Context Beef cattle feed efficiency is challenged in northern Australian production systems due to the limited dietary protein, leading changes rumen bacterial populations and fermentation outcomes. Aims Two types of diets with different protein contents were used evaluate composition diversity, aiming correlate parameters. Methods In total, 90 Brahman steers (341 ± 45 kg BW) selected for this trial, but fluid was collected from 85 steers, at 0 4 h after feeding, during a feed-efficiency trial. The fed low-protein diet, including 70% rumen-degradable 8.8% crude (CP) 60 days, followed by high-protein diet same period (13.5% CP). Liveweight dry-matter intake measurements, as well urine, faeces samples, determine efficiency, ruminal bacteria composition. Steers clustered into groups using principal component analysis Ward’s hierarchical method, differences parameters among clusters compared. Key results Rumen differed between (P < 0.01) diversity more related richness 0.01). there four distinct on basis bacteria, which most efficient better residual = 0.06) lower ammonia concentration before had highest relative abundance Prevotella While no observed or steer clusters. Conclusion shifting might contribute upregulate nitrogen recycling, favouring efficiency. Implications Identifying involved recycling upregulation be useful select diets.