Author
 |
Powell, Joseph |
|
Submitted to: FAO Technical Reports
Publication Type: Review Article Publication Acceptance Date: 8/29/2010 Publication Date: N/A Citation: N/A Interpretive Summary: Intensification of animal agriculture requires a greater dependence on purchased feed, which may increase environmental risks if manure production exceeds the recycling capacity of local land, air, and water resources. This paper provides summaries of integrated dairy nutrition/soil science research that depict relationships between lactating cow rations, feed use efficiencies, manure chemistry, and environmental outcomes of dairy production. The examples from dairy production will hold true for other livestock species: feeding protein above recommended levels will decrease feed nitrogen (N) use efficiency, increase excretions of N in manure, and subsequent N loss as ammonia gas. Unnecessary mineral supplements (such as phosphorus, P) will end up in manure, which will increase P loss in runoff from soil, and contaminate surface waters. These research examples illustrate that profitable rations can be developed to satisfy the nutritional demands of healthy, high-producing livestock, reduce manure excretion, and, therefore, enhance environmental performance of animal agriculture. Technical Abstract: The on-going trend of consolidation and intensification of animal agriculture requires a greater dependence on purchased feed. Increases in livestock numbers and feed imports may result in the excretion of manure nutrients that can surpass the recycling capacity of local land, air, and water resources. Government regulations have been enacted to improve manure management and the environmental performance of animal agriculture. This paper provides summaries of integrated dairy nutrition/soil science research that depict relationships between lactating cow rations, feed use efficiencies, manure chemistry, and some environmental outcomes of dairy production. Ration balancing, the use of total mixed rations, and milking thrice daily significantly enhances milk production and reduces manure production. The type and amount of forage fed to dairy cows impacts feed use efficiency, manure chemistry, and manure nitrogen (N) cycling in soil, including plant N uptake. Ammonia emissions from dairy barns, manure storage, and cropland after manure application can be related back to the N excreted by dairy cows in urine, which is linked to the concentrations of crude protein (CP) in cow rations. Similarly, as phosphorus (P) consumption by dairy cows increases, so does the excretion of soluble P in manure. Phosphorus runoff from cropland after manure application, which can pollute surface waters, can be related back to the P excreted in manure, which is linked to the concentrations of P in cow rations. These research examples illustrate that profitable rations can be developed to satisfy the nutritional demands of healthy, high-producing livestock, reduce manure excretion, and, therefore, enhance environmental performance of animal agriculture. |
