|Nisbet, David - Dave|
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/8/2005
Publication Date: 9/20/2005
Citation: Bozic, A., Anderson, R.C., Carstens, G.E., Ricke, S.C., Callaway, T.R., Yokoyama, M.T., Wang, J.K., Nisbet, D.J. 2005. Effects of nitroethane, lauric acid, Lauricidin and the Hawaiian marine algae, Chaetoceros, on ruminal methane production and some zoonotic pathogens in vitro. Proceedings of 2nd International Conference on Greenhouse Gases and Animal Agriculture (GGAA 2005). p. 440-443. Interpretive Summary: The gut of cattle can contain human pathogens such as E. coli O157:H7, Listeria, Salmonella and Campylobacter. These pathogens cause 3.9 million human infections in the U.S. each year. Methane is a gas produced by bacteria in the cow gut and costs the cattle industry as much as $900,000.00/day because it is an ineffecient process. In the present experiment, we tested the effects of lauric acid, Lauricidin® and the marine algae Chaetoceros on the survivability of Salmonella Typhimurium, E. coli O157:H7, and Listeria monocytogenes and found that while these compounds did not inhibit Salmonella or E. coli, they significantly reduced the survival of Listeria. We also tested these compounds for their ability to reduce methane production by a cow’s gut bacteria and found that they reduced methane production by > 90%. Another compound, nitroethane, known to inhibit Salmonella Typhimurium but not Listeria was also tested and found to reduce methane production by > 98%. These results suggest that the potential preharvest food safety benefits of supplementing cattle diets with nitroethane, lauric acid, Lauricidin® or the marine algae Chaetoceros may also reduce economic losses associated with methane production by cattle. These results may ultimately help cattle producers implement economically feasable strategies that will help them continue to produce safe and wholesome products for the American consumer.
Technical Abstract: The effects of the CH4-inhibitors, nitroethane (1 mg/ml), lauric acid (5 mg/ml), the commercial product, Lauricidin® (5 mg/ml), and a finely-ground product of the Hawaiian marine algae, Chaetoceros (10 mg/ml), were compared during consecutive batch culture (n = 3/treatment) of mixed populations of ruminal microbes. After the initial 24 h incubation, CH4 production by cultures incubated with nitroethane, lauric acid, Lauricidin® and the algae was reduced (P < 0.05) 98, 98, 92 and 92% from that by untreated control cultures (25.8 ± 8.1 µmol/ml). Methane production during the next two successive incubations was reduced at least 98% from controls (22.5 ± 3.2 and 23.5 ± 7.9 µmol/ml, respectively) for all treatments. Whereas nitroethane is known to inhibit the growth of Salmonella enterica serovar Typhimurium and Campylobacter jejuni, none of the other CH4-inhibitors were found to inhibit the growth of these zoonotic pathogens during in vitro culture (24 h) in fresh rumen fluid. Conversely, lauric acid and Lauricidin®, but not nitroethane, were found to inhibit the growth of Listeria monocytogenes >3.5 log10 units compared to controls (7.3 ± 0.1 log10 colony forming units/ml). These results suggest potential preharvest food safety benefits from supplementing cattle diets with nitroethane, lauric acid or Lauricidin®.