Evaluation of in vitro degradability of total mixed ration by synergistic supplementation of herbal extract-probiotic mixture in ruminants

Abstract

In Kerala, crossbred cattle feeding is restricted to grazing on low-quality forages with meagre allowances of concentrates and this necessitates the supplementation of feed additives for better utilisation of low quality feed resources. The probiotic culture of Aspergillus oryzae is widely used in ruminant nutrition because of its buffering function in stabilizing the rumen environment and stimulation of microbial activity especially fibrolytic activity. Psidium guajava leaves are antimethanogenic in action and the biological activities of these leaves include improving rumen fermentation and nutrient utilization in livestock. Hence a preliminary screening of the synergistic supplementation of different levels of A. oryzae and P. guajava leaf extracts at 0, 0.5, 0.25, and 0.125 per cent respectively in the total mixed ration (TMR) of concentrate: roughage (60:40) on dry matter(DM) basis was studied using in vitro gas production technique (IVGPT) with a view to estimate the metabolisable energy, digestible organic matter, methane production and in vitro degradable nitrogen(IVDN). The percentage of IVDN was significantly (p<0.01) higher for the treatment group supplemented with the herbal extract-probiotic mixture at 0.25% level. The percentage of methane production was significantly (p<0.01) lower for the treatment groups supplemented with the herbal extract-probiotic mixture at 0.5% and 0.25% with values of 8.42% and 10.8% respectively. The results indicated that synergistic supplementation of P. guajava leaf extract and A. oryzae probiotic culture each at 0.25% level in the TMR gave the best performance in terms of methane mitigation and optimum availability of IVDN for improved growth performance in crossbred dairy calves.