AUTHOR=Ebeid Hossam M. , Hassan Faiz-ul , Li Mengwei , Peng Lijuan , Peng Kaiping , Liang Xin , Yang Chengjian 

TITLE=Camelina sativa L. Oil Mitigates Enteric in vitro Methane Production, Modulates Ruminal Fermentation, and Ruminal Bacterial Diversity in Buffaloes

JOURNAL=Frontiers in Veterinary Science

VOLUME=7

YEAR=2020

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2020.00550

DOI=10.3389/fvets.2020.00550

ISSN=2297-1769

ABSTRACT=<p>This study was aimed to evaluate the effects of <italic>Camelina sativa</italic> oil (CO) on fermentation kinetics and methane (CH<sub>4</sub>) production in rations with different roughage (R) to concentrate (C) ratios. Three total mixed rations (TMRs) were used as substrates (R70:C30, R50:C50, and R30:C70) supplemented with different levels of CO (0, 2, 4, 6, and 8% on dry matter basis) in an <italic>in vitro</italic> batch culture system. The enteric CH<sub>4</sub> production was determined at different times of incubation while fermentation parameters were measured at the end of incubation. Results revealed that CO significantly decreased (<italic>P</italic> &lt; 0.05) CH<sub>4</sub> production at 48 h in medium (R50:C50) and low- (R30:C70) roughage diets than control. Camelina oil at all levels significantly (<italic>P</italic> &lt; 0.05) affected ammonia nitrogen (NH<sub>3</sub>-N) and microbial protein (MCP) in all rations. Propionate concentration was increased by supplementing 8% CO to R70:C30 TMR, but it decreased with increasing levels of CO for low- and medium-roughage diets. Acetate concentration was significantly (<italic>P</italic> &lt; 0.05) higher at 4% CO supplementation, but it decreased with 8% CO level in R30:C70 TMR. For all rations, CO decreased (<italic>P</italic> &lt; 0.001) total bacteria, protozoa, and methanogens. Total fungi counts were affected by CO in all rations, especially with a 6% level in two rations (R30:C70 and R50:C50) and 8% level with high-roughage ration (R70:C30). Supplementation of CO in medium-roughage ration (R50:C50) showed a linear (<italic>P</italic> &lt; 0.05) decrease in bacterial richness and evenness indices along with Shannon diversity as compared to the control. Moreover, CO also increased <italic>Firmicutes</italic> to <italic>Bacteroidetes</italic> ratio in all TMRs more effectively at higher levels. Camelina oil also affected the relative abundance of <italic>Prevotella</italic> in both low- and medium-roughage diets while increasing the abundance of <italic>Ruminobacter</italic> and <italic>Pseudobutyrivibrio</italic>. The present study concluded that CO enhanced fermentation kinetics while decreasing enteric <italic>in vitro</italic> CH<sub>4</sub> production from fibrous diets. Thus, it may be considered as a potentially effective and environmentally friendly way of mitigating CH<sub>4</sub> emission from livestock.</p>