Dynamics of gastrointestinal activity and ruminal absorption of the methane-inhibitor, nitroethane, in cattle

Authors: BOZIC, ALEKSANDAR - University Of Novi Sad; GUTIÉRREZ-BAÑUELOS, HECTOR - Autonomous University Of Zacatecas; CORRAL-LUNA, AGUSTIN - Universidad Autonoma De Chihuahua; CARSTENS, GORDON - Texas A&M University; ARÉVALOS-SÁNCHEZ, MARTHA MARÍA - Universidad Autonoma De Chihuahua; FÉLIX-PORTILLO, MONSERRATH - Universidad Autonoma De Chihuahua; MURO-REYES, ALBERTO - Autonomous University Of Zacatecas; ARZOLA-ÁLVAREZ, CLAUDIO - Universidad Autonoma De Chihuahua; Anderson, Robin; Harvey, Roger

Submitted to: Frontiers in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2022
Publication Date: 2/3/2022
Citation: Bozic, A.K., Gutiérrez-Bañuelos, H., Corral-Luna, A., Carstens, G., Arévalos-Sánchez, M., Félix-Portillo, M., Muro-Reyes, A., Arzola-Álvarez, C., Anderson, R.C., Harvey, R.B. 2022. Dynamics of gastrointestinal activity and ruminal absorption of the methane-inhibitor, nitroethane, in cattle. Frontiers in Veterinary Science. 9. Article 817270. https://doi.org/10.3389/fvets.2022.817270.
DOI: https://doi.org/10.3389/fvets.2022.817270

Interpretive Summary: Methane production by the microbial community within the anaerobic fiber-degrading stomach of cattle represents a digestive inefficiency that results in losses of up to 12% of the animal's energy intake and contributes to nearly 27% of the United States emissions of this potent greenhouse gas. Nitroethane is a potent methane-inhibiting chemical for cattle, but little is known regarding effects of repeated administration on the methane-producing activity in the animal's fiber-degrading organ (called the rumen) or its intestinal tract which processes the residual digestion products that flow out of the rumen. Moreover, nothing is known about the potential for absorption of nitroethane in cattle. These results provide important information regarding effects of nitroethane administration to cattle and ultimately may lead to practical treatments to reduce economic and environmental costs of methane production in cattle, thereby helping farmers and ranchers produce wholesome meat and milk at less cost while being better for the environment.

Technical Abstract: Ruminal methane production represents a digestive inefficiency for the host, resulting in losses of up to 12% of the gross energy consumed by the animal and contributes nearly 27% of the total United States’ emissions of this potent greenhouse gas. Nitroethane is a potent methane-inhibitor for ruminants, but little is known regarding simultaneous effects of repeated administration on pre- and post-gastric methane-producing activity and potential absorption and systemic accumulation of nitroethane in ruminants. Intraruminal administration of 120 mg nitroethane/kg body weight to Holstein cows over a 4-day period transiently reduced (P < 0.05) ruminal methane-producing activity as much as 3.6-fold, while concomitantly increasing (P < 0.05) fecal-methane producing activity by as much as 8.8-fold when compared to pre-treatment measurements. These observations suggest a bacteriostatic effect of nitroethane on ruminal methanogen populations resulting in increased passage of viable methanogens to the lower bovine gut. Ruminal VFA concentrations were also transiently affected by nitroethane administration (P < 0.05) reflecting adaptive changes in the rumen microbial populations. Mean (± SD) nitroethane concentrations in plasma of feedlot steers administered 80 or 160 mg nitroethane/kg body weight over a 7-day period were 0.12 ± 0.1 and 0.41 ± 0.1 µmol/mL 8 hours after the initial administration indicating rapid absorption of nitroethane, with concentrations peaking 1 day after initiation of the 80 or 160 mg nitroethane/kg body weight per day treatments (0.38 ± 0.1 and 1.14 ± 0.1 µmol/mL, respectively). Plasma nitroethane concentrations declined thereafter to 0.25 ± 0.1 and 0.78 ± 0.3 and to 0.18 ± 0.1 and 0.44 ± 0.3 µmol/mL on days 2 and 7 for the 80 or 160 mg nitroethane/kg body weight per day treatment groups, respectively, indicating decreased absorption due to increased ruminal nitroethane degradation or to more rapid excretion of the compound. These results provide important information regarding effects of nitroethane administration to cattle and are consistent with ruminal in situ enrichment of nitroethane-degrading bacteria.