In vitro reduction of methane production by 3-nitro-1-propionic acid is dose-dependent

Authors: OCHOA-GARCIA, PEDRO - Universidad Autonoma De Chihuahua; AREVALOS-SANCHEZ, MARTHA - Universidad Autonoma De Chihuahua; RUIZ-BARRERA, OSCAR - Universidad Autonoma De Chihuahua; Anderson, Robin; MAYNEZ-PEREZ, ADRIAN - Universidad Autonoma De Chihuahua; RODRIGUEZ-ALMEIDA, FELIPE - Universidad Autonoma De Chihuahua; CHAVEZ-MARTINEZ, AMERICA - Universidad Autonoma De Chihuahua; GUTIERREZ-BANUELOS, HECTOR - Autonomous University Of Zacatecas; CORRAL-LUNA, AGUSTIN - Universidad Autonoma De Chihuahua

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2019
Publication Date: 3/1/2019
Publication URL: http://handle.nal.usda.gov/10113/6471142
Citation: Ochoa-Garcia, P.A., Arevalos-Sanchez, M.M., Ruiz-Barrera, O., Anderson, R.C., Maynez-Perez, A.O., Rodriguez-Almeida, F.A., Chavez-Martinez, A., Gutierrez-Banuelos, H., Corral-Luna, A. 2019. In vitro reduction of methane production by 3-nitro-1-propionic acid is dose-dependent. Journal of Animal Science. 97(3):1317-1324. https://doi.org/10.1093/jas/skz012.
DOI: https://doi.org/10.1093/jas/skz012

Interpretive Summary: The production of methane in the cow stomach is considered an inefficient process because it can result in the loss of 4 to 12% of the dietary energy consumed by the host and can be an important source for the emission of this greenhouse gas. Recent studies have shown that some chemicals referred to as short chain nitrocompounds are capable of inhibiting the production of methane in the stomach of cows but optimal doses have yet to be determined. In the present study, a naturally occurring nitrocompound, technically named 3-nitro-1-propionic acid, was studied for its potential to inhibit methane production. We found that this compound, abbreviated 3NPA, reduced methane production in a dose-dependent manner by 29 to 96% when compared to the amount produced by untreated controls. Effects of 3NPA treatment were also observed on amounts of total gas and other digestion end products, but these indicated that 3NPA beneficially affected digestion efficiency. Results further revealed that the microbes in the cow stomach were able to metabolize more than 60% of the added 3NPA to a useful end product which means there was little risk of the inhibitory compound ending up in meat or milk. These results provide important information to help scientists develop practical supplementation strategies for cows to better utilize the feed they eat while at the same time reducing the emission of methane to the atmosphere. Ultimately, this research may lead to practical supplementation strategies to help cattlemen produce wholesome meat and milk at less cost for the American consumer and with less negative environmental impact.

Technical Abstract: Methanogenesis is a metabolic process that allows the rumen ecosystem the ability to maintain low partial pressures of hydrogen needed for proper digestive function. However, rumen methanogenesis is also considered an inefficient process because it can result in the loss of 4 to 12% of the total energy consumed by the host. Recent studies have shown that some short chain nitrocompounds such as nitroethane, 2-nitroethanol, 2-nitro-1-propanol, and 3-nitro-1-propionic acid are capable of inhibiting the production of methane during in vitro culture; however, optimal supplementation doses have yet to be determined. In the present study, the naturally-occurring nitrocompound 3-nitro-1-propionic acid (3NPA) was supplemented to in vitro cultures of freshly collected mixed populations of ruminal microbes to achieve 0, 3, 6, 9, or 12 mM. Analysis of fermentation products after 24 h of incubation revealed that methane production was reduced in a dose-dependent manner by 29 to 96% (P less than 0.05), compared to the amount produced by untreated controls (15.03 plus or minus 0.88 µmol mL**-1 incubated liquid). Main effects of treatment were also observed on amounts of total gas and volatile fatty acids produced, as well as on rates of 3NPA degradation, the latter varying from 0.07 to 0.30 µmol mL**-1. Changes in production of metabolites produced indicated that the caloric fermentation efficiency was not compromised by 3NPA treatment. Results further revealed that the microbial populations were able to metabolize more than 60% of the added nitrocompound, with the amount degraded being greatest in cultures treated with 12 mM 3NPA.