Maggot oil as a feed supplement for reducing methanogenesis of rumen microbial culture in vitro

Hermetia illucens larvae or known as maggot contains considerable amount of oil in its body. This experiment aimed to evaluate the use of maggot oil as a feed supplement for reducing methanogenesis of rumen microbial culture in vitro. The oil was supplemented into a feed substrate that consisted of forage: concentrate mixture (3:2 w/w). Supplementation of the oil was performed at different levels, i.e., 0, 1, 2, 3, 4 and 5% from substrate dry matter. All incubation bottles were tightly closed and incubated for 24 h in a water bath that maintained at 39oC. Results revealed that maggot oil at 4 and 5% supplementation level was able to reduce methane emission by 20.7 and 26.9% (P<0.05) in comparison to control, respectively. However, its supplementation at 3% or lower did not alter the methane emission. The organic matter digestibility parameter was linearly reduced with increasing level of maggot oil supplementation (P<0.05), but volatile fatty acid concentration was not affected. In contrast to our expectation, maggot oil at 3 to 5% increased log protozoa population and ammonia concentration than those of control (P<0.05). In conclusion, maggot oil may serve as a promising supplement for mitigating ruminal methanogenesis and the effect is dose-dependent.