Submitted to: Sustainable Agriculture
Publication Type: Abstract only
Publication Acceptance Date: 4/22/1998
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Dairy producers are challenged with improving production efficiency while reducing the environmental impact of excreted nutrients. There is a critical balance between meeting animal requirements and minimizing excretion of N, P, and K. We must establish this balance to satisfy economic and environmental pressures. Once excreted,large amounts of nutrients can be lost to the environment. Strategies that reduce the loss of nutrients and methods of predicting manure composition will be important tools for providing maximal nutrients to crops and minimizing environmental impacts. We conducted a lactation study to evaluate the effect of fiber source and level on milk production and animal weight. In two dietary treatments, alfalfa or orchardgrass provided equal amounts of fiber in combination with high moisture corn. A third treatment had more dietary fiber than the first two treatments with orchardgrass at the same forage to concentrate ratio as the alfalfa diet. Manure from these cows was used in companion studies to determine the volatilization rate of the inorganic N and the plant availability of the organic N. Manure samples were spread over a smooth surface and covered with plexiglass tunnels. Air was drawn over the manure and volatilized ammonia was recovered in an acid trap. To determine the rate and extent of N and C mineralization, manure was incubated with soil and the appearance of ammonia plus nitrate and the production of CO2 were monitored over 16 weeks. Preliminary results indicate that milk production was similar for the cows fed diets containing equal amounts of fiber but less for the cows fed a greater amount of fiber. The rate and extent of ammonia volatilization were highest for manures from cows receiving alfalfa silage.