ARS | Publication request: Zoonotic bacterial populations, gut fermentation characteristics and methane production in feedlot steers during oral nitroethane treatment and after the feeding of an experimental chlorate product

Submitted to: Anaerobe
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 10, 2006
Publication Date: January 5, 2007
Citation: Gutierrez-Banuelos, H., Anderson, R.C., Carstens, G.E., Slay, L.J., Ramlachan, N., Horrocks, S.M., Callaway, T.R., Edrington, T.S., Nisbet, D.J. 2007. Zoonotic bacterial populations, gut fermentation characteristics and methane production in feedlot steers during oral nitroethane treatment and after the feeding of an experimental chlorate product. Anaerobe. 13:21-31.

Interpretive Summary: Experiments were conducted with feedlot cattle to test the ability of nitroethane and an experimental chlorate product, chemicals discovered in laboratory studies to reduce concentrations of certain food contaminating bacteria. Contrary to findings from numerous laboratory studies, results from our animal study did not support our hypothesis that nitroethane would reduce gut concentrations of Campylobacter and Salmonella, bacteria that cause most cases of foodborne disease. Evidence indicated that rapid absorption and degradation in the gut prevented accumulations of nitroethane to levels needed to be kill these pathogens. This suggests that further studies are needed to determine optimal dose levels. Our results did demonstrate, however, that nitroethane administration reduced methane-producing activity in gut contents of the steers by as much as 40%. Methane production by cattle is a digestive inefficiency that results in the loss of up to 12% of the animals daily energy intake. Furthermore, our results showed that feeding chlorate in the steers’ last day’s meal significantly reduced gut E. coli concentrations by >1000-fold. Taken together, these results provide a basis for developing feed additives for cattle that both enhance food safety and dietary energy utilization. Ultimately, this research will help cattle farmers continue to produce wholesome and safe food products at less cost for the American consumer.

Technical Abstract: Nitroethane inhibits the growth of certain zoonotic pathogens such as Campylobacter and Salmonella spp., foodborne pathogens estimated to cause millions of human infections each year, and enhances the Salmonella- and E. coli-killing effect of an experimental chlorate product being developed as a feed additive to kill these bacteria. Nitroethane is suspected to also inhibit ruminal methane (CH4) production, which represents a loss of 2–12% of the host’s gross energy intake. This study was conducted to assess the effects of 14-day oral nitroethane administration, 0 (0X), 80 (1X) or 160 (2X) mg nitroethane/kg body weight per d on ruminal and fecal E. coli and Campylobacter, and on ruminal and fecal CH4-producing and nitroethane-reducing activity in Holstein steers (n = 6 per treatment). An experimental chlorate product was fed the day following the last nitroethane administration to determine effects on E. coli and Campylobacter. The experimental chlorate product, reduced (P < 0.001) fecal, but not ruminal (P > 0.05) E. coli concentrations by 1000- and 10-fold by 24 and 48 h after chlorate feeding when compared to pretreatment concentrations (> 5.7 log10 colony forming units/g). No effects (P > 0.05) of nitroethane or the experimental chlorate product were observed on Campylobacter. Nitroethane treatment decreased ruminal and fecal CH4-producing activity (P < 0.01) (8.46, 7.91 and 4.74 ± 0.78 umol/g h**-1, for ruminal samples, and 3.90, 1.36 and 1.38 ± 0.50 umol/g h**-1 in fecal material; mean ± SEM, for treatments 0X, 1X and 2X respectively) and increased (P < 0.001) ruminal but not fecal (P > 0.05) nitroethane-reducing activity. Results confirm the bactericidal activity of chlorate against E. coli and demonstrate that nitroethane reduces methane production in the bovine gut.