Dynamics of the ruminal microbial ecosystem, and inhibition of methanogenesis and propiogenesis in response to nitrate feeding to Holstein calves

Abstract

It is known that nitrate inhibits ruminal methanogenesis, mainly through competition with hydrogenotrophic methanogens for available hydrogen (H 2 ) and also through toxic effects on the methanogens. However, there is limited knowledge about its effects on the others members of ruminal microbiota and their metabolites. In this study, we investigated the effects of dietary nitrate inclusion on enteric methane (CH 4 ) emission, temporal changes in ruminal microbiota, and fermentation in Holstein calves. Eighteen animals were maintained in individual pens for 45 d. Animals were randomly allocated to either a control (CTR) or nitrate (NIT, containing 15 g of calcium nitrate/kg dry matter) diets. Methane emissions were estimated using the sulfur hexafluoride (SF 6 ) tracer method. Ruminal microbiota changes and ruminal fermentation were evaluated at 0, 4, and 8 h post-feeding. In this study, feed dry matter intake (DMI) did not differ between dietary treatments ( P > 0.05). Diets containing NIT reduced CH 4 emissions by 27% (g/d) and yield by 21% (g/kg DMI) compared to the CTR ( P < 0.05). The pH values and total volatile fatty acids (VFA) concentration did not differ between dietary treatments ( P > 0.05) but differed with time, and post-feeding ( P < 0.05). Increases in the concentrations of ruminal ammonia nitrogen (NH 3 –N) and acetate were observed, whereas propionate decreased at 4 h post-feeding with the NIT diet ( P < 0.05). Feeding the NIT diet reduced the populations of total bacteria, total methanogens, Ruminococcus albus and Ruminococcus flavefaciens , and the abundance of Succiniclasticum , Coprococcus , Treponema , Shuttlewortia , Succinivibrio , Sharpea , Pseudobutyrivibrio , and Selenomona ( P < 0.05); whereas, the population of total fungi, protozoa, Fibrobacter succinogenes , Atopobium and Erysipelotrichaceae L7A_E11 increased ( P < 0.05). In conclusion, feeding nitrate reduces enteric CH 4 emissions and the methanogens population, whereas it decreases the propionate concentration and the abundance of bacteria involved in the succinate and acrylate pathways. Despite the altered fermentation profile and ruminal microbiota, DMI was not influenced by dietary nitrate. These findings suggest that nitrate has a predominantly direct effect on the reduction of methanogenesis and propionate synthesis.

Rumen microbial-driven metabolite from grazing lambs potentially regulates body fatty acid metabolism by lipid-related genes in liver

“…Taken together, it is relevant to analyze the effects on FAs brought about by feeding patterns. The ruminal VFA concentration is the crucial factor that can reflect the impact of different feeding treatments on ruminal fermentation [ 25 ]. Similar to a previous study, rumen fermentation characteristics were significantly affected due to the differences in feeding pattern, which represented the increased carbohydrate fermentation in the rumen of indoor feeding lambs [ 26 ].…”

Effects of Fumarate and Nitroglycerin on In Vitro Rumen Fermentation, Methane and Hydrogen Production, and on Microbiota

“…It seems that the combination of the two chemicals had an opposite impact on Succinivibrio. Treponema, belonging to Spirochaetae, produces succinate, formate and acetate [43]. The relative abundance of Treponema was restored by the addition of fumarate.…”

A preliminary study on the possibility of fermented pineapple peel residue partially replacing whole corn silage in feeding Chuanzhong black goats

“…s_Butyrivibrio fibrisolvens can increase the content of conjugated linoleic acid in the intestine and adipose tissue (Srivastava et al, 2021) and produce diverse carbohydrate-active enzymes that hydrolyze cellulose and other plant-derived macromolecular polymers (Sengupta et al, 2022). This bacterium is similar to s_Ruminococcus albus, which can also synthesize some types of hydrolytic enzymes that help ruminants digest plant-based feed (Storani et al, 2020;Ortiz-Chura et al, 2021). Firmicutes and Bacteroidetes are essential for ruminant digestion.…”