Effect of a Composite Phytochemical Feed Additive on In Vitro Substrate Degradation and Methanogenesis and In Vivo Rumen Fermentation

The present study was carried out to evaluate the potential of a composite phytogenic feed additive (cPFA) on rumen fermentation characteristics under in vitro as well as in vivo conditions. The cPFA was formulated using different parts of 11 herbal plants, well acclaimed for their therapeutic virtues. Graded levels (0, 1.0, 1.5, 2.0, 2.5, 5.0. 7.5 and 10%) of cPFA were supplemented to the basal substrate and incubated with rumen liquor of sheep for in vitro gas production test and methanogenesis. For in vivo study 28 Malpura hogget lambs (7-8 months; 17.8 +/- 2.04 kg) were divided in four equal groups and fed diets supplemented with cPFA at 0 (Control). 1.0 (L-cPFA), 1.5 (M-cPFA) and 2.0 (H-cPFA) percent of feed intake. At the end of experimental feeding of 180d, rumen liquor was collected at 4h post feeding. Results indicated that, in vitro supplementation of cPFA reduced (P < 0.05) total gas production and improved (P < 0.05) the microbial biomass production. There was a linear increase (P < 0.05) in ammonia concentration accompanied by a reduction (P < 0.05) in acetate concentration. There emerged a linear decrease (P < 0.05) in methane production up to a level of 5% cPFA supplementation. In vivo study revealed that there was no effect of cPFA supplementation on pH, ammonia and different nitrogen fractions in strained rumen liquor (SRL) among the groups; however, a trend of improvement in the total N was evident in cPFA supplemented groups when contrasted against control. The level of 1.5 and 2.0% cPFA supplementation showed higher (P=0.02) acetate concentration values. The cPFA supplementation did not have significant effect on enzyme activities of CMCase, avicellase and xylanase in the SRL. The present study revealed that supplementation of cPFA at level of 1.5-2.0% level possesses a potential to modulate rumen fermentation both under in vitro as well as in vivo conditions.