<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>Modifying the chemical composition of a diet can be a good strategy for reducing methane emission in the rumen. However, this strategy can have adverse effects on the ruminal microbial flora. The aim of our study was to reduce methane without disturbing ruminal function by stimulating the growth and propagation of methanotrophs. In this study, we randomly divided twenty multiparous Holstein dairy cows into 4 groups in a 2×2 factorial design with two forage levels (40% and 60%) and two nitrate supplementation levels (3.5% and zero). We examined the effect of experimental diets on cow performance, ruminal fermentation, blood metabolites and changes of ruminal microbial flora throughout the experimental period (45-day). Additionally, <italic>in vitro</italic> methane emission was evaluated. Animals fed diet with 60% forage had greater dry matter intake (DMI) and milk fat content, but lower lactose and milk urea content compared with those fed 40% forage diet. Moreover, nitrate supplementation had no significant effect on DMI and milk yield. Furthermore, the interactions showed that nitrate reduces DMI and milk fat independently of forage levels. Our findings showed that nitrate can increase ammonia concentration, pH, nitrite, and acetate while reducing the total volatile fatty acids concentration, propionate, and butyrate in the rumen. With increasing nitrate, methane emission was considerably decreased possibly due to the stimulated growth of <italic>Fibrobacteria</italic>, <italic>Proteobacteria</italic>, type II Methanotrophs, and <italic>Methanoperedense nitroreducens</italic>, especially with high forage level. Overall, nitrate supplementation could potentially increase methane oxidizing microorganisms without adversely affecting cattle performance.</p>
</abstract>

Modifying the chemical composition of a diet can be a good strategy for reducing methane emission in the rumen. However, this strategy can have adverse effects on the ruminal microbial flora. The aim of our study was to reduce methane without disturbing ruminal function by stimulating the growth and propagation of methanotrophs. In this study, we randomly divided twenty multiparous Holstein dairy cows into 4 groups in a 2×2 factorial design with two forage levels (40% and 60%) and two nitrate supplementation levels (3.5% and zero). We examined the effect of experimental diets on cow performance, ruminal fermentation, blood metabolites and changes of ruminal microbial flora throughout the experimental period (45-day). Additionally, in vitro methane emission was evaluated. Animals fed diet with 60% forage had greater dry matter intake (DMI) and milk fat content, but lower lactose and milk urea content compared with those fed 40% forage diet. Moreover, nitrate supplementation had no significant effect on DMI and milk yield. Furthermore, the interactions showed that nitrate reduces DMI and milk fat independently of forage levels. Our findings showed that nitrate can increase ammonia concentration, pH, nitrite, and acetate while reducing the total volatile fatty acids concentration, propionate, and butyrate in the rumen. With increasing nitrate, methane emission was considerably decreased possibly due to the stimulated growth of Fibrobacteria, Proteobacteria, type II Methanotrophs, and Methanoperedense nitroreducens, especially with high forage level. Overall, nitrate supplementation could potentially increase methane oxidizing microorganisms without adversely affecting cattle performance.

Influence of nitrate supplementation on <italic>in-vitro</italic> methane emission, milk production, ruminal fermentation, and microbial methanotrophs in dairy cows fed at two forage levels

Department of Animal Science, Faculty of Agriculture

Autonomous University of the State of Mexico

Annals of Animal Science

This work is licensed under the Creative Commons Attribution 4.0 International License.

Influence of nitrate supplementation on  methane emission, milk production, ruminal fermentation, and microbial methanotrophs in dairy cows fed at two forage levels

Modifying the chemical composition of a diet can be a good strategy for reducing methane emission in the rumen. However, this strategy can have adverse effects...

Influence of nitrate supplementation on in-vitro methane emission, milk production, ruminal fermentation, and microbial methanotrophs in dairy cows fed at two forage levels

Published Online: Jul 19, 2022

Page range: 1015 - 1026

Received: Jan 11, 2021

Accepted: Oct 19, 2021

DOI: https://doi.org/10.2478/aoas-2021-0087

Keywords
dairy cows, forage, methanotrophs, microbiota, milk yield, nitrate, ruminal fermentation

© 2021 Majid Sharifi et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Influence of nitrate supplementation on in-vitro methane emission, milk production, ruminal fermentation, and microbial methanotrophs in dairy cows fed at two forage levels

Published Online: Jul 19, 2022

Page range: 1015 - 1026

Received: Jan 11, 2021

Accepted: Oct 19, 2021

DOI: https://doi.org/10.2478/aoas-2021-0087

Keywordsdairy cows, forage, methanotrophs, microbiota, milk yield, nitrate, ruminal fermentation

© 2021 Majid Sharifi et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Keywords
dairy cows, forage, methanotrophs, microbiota, milk yield, nitrate, ruminal fermentation