N and P Use Status in Small and Medium Sized Dairy Herds.

Small and medium sized dairy farms are exempted from EPA nutrient management regulations, but can account for a major proportion of animals in traditional agriculture regions. Reducing nutrient loading to sensitive waters is a responsibility that needs to be shared by animal operations of all scales. Ten dairy farms with 50 to 250 cows in the Chesapeake Bay watershed were monitored for nutrient utilization for 2 yr in comparison with baseline data collected during the first 3 mo of the project. Farms were evaluated regularly for nutrition and management practices and presented with recommendations for improvement, as appropriate. Diets and feces were sampled quarterly and analyzed for nutrient content. DHIA reports were collected monthly. Most of the farms fed dietary P appropriately, and half of the farms reduced dietary protein during monitoring, averaging 0.38% in P and 16.5% in CP, both consistent with current industry usages and NRC standards. However, variation existed in the diets as well as fecal analysis among farms and over time within farms. Analyzed dietary P exceeded formulated concentrations, whereas the trend was the opposite for protein. While combined data across farms showed that there was little change in milk production or MUN during the monitoring period, half of the farms showed improvements. Seven of the 10 farms had increases in pregnancy rate. Although not mandated to implement nutrient management plans, producers of small and medium farms were conscientious about dietary CP and P content, and willing to adopt new technologies to reduce excretion.