Submitted to: High Plains Beef Conference
Publication Type: Proceedings
Publication Acceptance Date: August 7, 1998
Publication Date: N/A
Technical Abstract: The feeding of livestock in confinement leads to concentration of feed nutrients such as nitrogen (N) and carbon (C) into a relatively small area. Nutrition and management practices can influence the amount of N and C excreted as well as influence transformations and movements of N and C that occur after excretion. Nitrogenous compounds in feces and urine can potentially pollute ground or surface waters. Nitrogen that volatilizes from the soil or water surface, primarily as ammonia or nitrous oxide, can lead to air pollution. Losses of carbon occur primarily as carbon dioxide or methane produced during normal respiration, fermentation within the gut, or by fermentation of manure. The ruminant has the capacity to recycle N from the lower gut or tissues to the rumen where it can be used for synthesis of protein by the ruminal microorganisms. Compared to cattle on pasture, cattle fed high-concentrate diets produce smaller quantities of methane as a percentage of gross energy intake (approximately 6-10 vs 3%). However, greater quantities of methane may be produced from the manure of cattle in feedlots than cattle in pastures. Nitrogen use is affected by animal genetics, dietary protein concentration, dietary protein source, energy intake, ionophores, growth promoting implants, and other factors. We currently have studies in progress to evaluate nutritional practices that decrease excretion of N and P by feedlot cattle, and laboratory studies to develop soil amendments that can decrease losses of N and C from feedyards. Preliminary results indicate that adding alum to the soil surface can decrease ammonia losses by as much as 80%, however, currently the cost is prohibitive.