Use of in vitro gas production to evaluate associative effects on gas production of rice straw supplemented with lucerne

A semi-automated in vitro gas production (GP) system was used to investigate the associative effects on GP of rice straw (RS) supplemented with 0, 20, 40, 60, 80 and 100% lucerne hay (LH). Rate of GP increased with increasing levels of LH (P<0.05). Potential GP values were also affected by LH levels in the substrates, but only some significant effects were observed (P<0.05). The associative effects were maximal at 24 h incubation and then declined with duration of incubation at all inclusion levels of LH. Supplementation with 40-60% of LH to RS could produce the optimal associative effects on GP.