|Powell, J Mark|
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 30, 2013
Publication Date: April 1, 2013
Citation: Powell, J.M., Broderick, G.A. 2013. What we feed dairy cows impacts manure chemistry and the environment. Waste to Worth: Spreading Science and Solutions 2013. p. 63-64. Technical Abstract: During the last part of the 20th century, animal manure management became an environmental concern. In response to these concerns, legislation was enacted to control manure management and the emission of undesirable gasses (e.g., ammonia and methane) from animal production systems. The purpose of this paper is to illustrate how mineral phosphorus (P) supplements, forage types and amounts, and the crude protein (CP) fed to lactating cows impact manure chemistry and the fate of manure nutrients in the environment. Source-sink relationships are used to illustrate relationships between ration nutrient sources (e.g., forms and concentrations of P and CP) and nutrient sinks (milk and manure), and relationships between manure nutrient sources (e.g., soluble P, urea nitrogen (N)) and sinks [soil test P, runoff P, atmospheric ammonia, soil inorganic N, crop N] and the impact of these relationships on the environment. For example, as mineral P concentrations in dairy rations increase, the excretion of total P and soluble P in manure also increases. Runoff of soluble P from cropland after manure application, which can contaminate surface waters, can be related back to the P excreted in manure, which in turn can be linked to the amount of mineral P in cow rations. Likewise, the type and amount of CP and forage fed to dairy cows impact manure chemistry and manure N cycling in soil, including plant N uptake. Ammonia emissions from dairy barns and soil after manure application can be related back to the urea N excreted by dairy cows in urine, which is linked to the types and concentrations of CP and forages in cow rations. Our results demonstrate that profitable rations can be fed to satisfy the nutritional demands of healthy, high-producing dairy cows, reduce manure excretion and therefore the environmental impacts of milk production.