Malic acid-heat- treatment of proteins reduces methane and nitrogen emissions with improvement in growth, feed efficiency and nutrient utilization in Murrah buffalo (Bubalus bubalis)

Feeds rich in rumen protected protein that are associated with reduced methane production would be of higher relative importance as components of ruminant feeding systems. The current study aimed at combining malic acid and heat treatment (MAH), a novel technique to enhance the rumen undegradable fraction of feed protein in order to augment post-ruminal amino acid availability to the animals. This study consisted of two experimental trials: in vitro and in vivo . The in vitro trial was conducted using a completely randomized design with 0% (control), 50% (T-1), and 100% (T-2) replacement levels of untreated protein feeds (guar korma and groundnut cake) with MAH-treated guar korma and groundnut cake in total mixed rations. In vitro findings revealed significant (p< 0.05) reduction of methane production and ammonia-nitrogen levels in T-1 and T-2 groups without adversely affecting other in vitro fermentation parameters, such as feed degradability and volatile fatty acid production. The in vivo trial was conducted with eighteen female Murrah buffalo calves, divided into three groups in a completely randomized design (control, T-1, and T-2) over a 90-day period. The results revealed a significant (p< 0.05) increase in growth rate (57.62%) and an improvement in feed efficiency (54.15%) in the T-2 group compared to the control. The digestibility coefficients of nutrients viz. dry matter, organic matter, crude protein, neutral detergent fibre, and acid detergent fibre were also improved (p<0.05) in animals of T-2 group. A reduction (38.62%) in methane production was evidenced in calves replaced with 100% MAH treated protein feeds (T-2). An enhanced (p<0.05) nitrogen retention (% of N intake and absorbed) was demonstrated in buffalo calves fed with MAH treated guar korma and groundnut cake as protein supplements. Therefore, the study demonstrated that the malic acid-heat treatment is an effective technology to protect protein from ruminal degradation for enhancing production performance and abate the environmental impact of livestock rearing. • Novel technique of malic acid-heat treatment of protein feeds increases bypass protein content of feeds • The process reduced in vitro methane and ammonia production with increased propionate content • In vivo feeding enhanced growth rate (57.62%) and feed efficiency (54.15%) in Murrah buffalo calves • Increased in vivo nutrient digestibility and nitrogen retention • Reduced methane (38.62%) and nitrogen emission in buffaloes