Effects of Plants Containing Secondary Metabolites on Ruminal Methanogenesis of Sheep in vitro

The current study was carried out to determine the effect of secondary metabolites on in vitro rumen microbial fermentation and their potential to inhibit methane (CH4) production involved in the global warming and greenhouse-gases. The obtained results showed that the addition of Yucca schidigera and Quillaja saponaria reduced significantly CH4 production (P <0.05). This reduction is proportional to the concentration and it becomes superior to 60% beyond 8 mg / ml of saponins. CH4 production and total volatile fatty acid (tVFA) concentration decreased linearly (P<0.05) with increasing dose of essential oils (EO). The effect was more pronounced with Mentha pulegium. The incorporation of Acacia cyanophylla tannins source to vetch-oat hay leads to a relative decrease in CH4 in the gas pool. Supplementation with 60% and 30% of Acacia cyanophylla resulted in 37.5% and 56.25% lower CH4, respectively. Addition of Acacia cyanophylla reduced significantly tVFA. The proportion of 60% of Acacia cyanophylla induced the highest molar proportion in propionate. The results showed that plant secondary metabolites can be used as feed additives to reduce CH4 production and to consequently mitigate greenhouse-gases emissions.