Assessment of forage preparation, pequi oil (Caryocar brasiliense) supplementation and incubation temperature on methane emissions and microbial communities using a rumen simulation technique (RUSITEC)

Abstract

This thesis comprises three in vitro studies using the rumen simulation technique (RUSITEC). The aims were to evaluate rumen microbial communities and fermentation characteristics in response to forage preparation (changes in feed particle size), by pequi oil supplementation, or by change in incubation temperature. Methane production was evaluated in all studies with the purpose to understand the suppressing effect in relation with microbial composition. A variety of molecular technique approaches were applied for the analysis of microbial communities including single strand conformation polymorphism (SSCP), real time polymerase chain reaction qPCR and high-throughput sequencing. Results obtained from these studies confirm the overall complexity of the rumen microbiome. Archaeal and bacterial community composition varies significantly between fresh and dried forage preparation. A tendency to increase methane production was observed in the fresh forage preparation (frozen minced) compared to freeze-dried and ground. Lipid supplementation with pequi oil, which is rich in unsaturated fatty acids, had neither major effect on archaeal and bacterial communities, nor on methane reduction. On the contrary, a decrease of 4°C in temperature suggested an effect on microbial composition and resulted in a 57% decreased of methane emissions. Evidence obtained from this thesis demonstrate the opportunities to enhance the knowledge and understanding of interactions within the rumen ecosystem to continue developing mitigation strategies in order to counteract the impact of livestock on climate change.