Title page for ETD etd-10292003-105938

Type of Document Master's Thesis
Author Wydner III, Fred Preston
URN etd-10292003-105938
Title Nutritional and Management Practices to Reduce Excessive Nutrient Excretion on Dairy Farms
Degree Master of Science
Department Dairy Science
Advisory Committee
Advisor Name Title
James, Robert E. Committee Chair
Knowlton, Katharine F. Committee Co-Chair
Jones, Gerald M. Committee Member
McGilliard, Michael L. Committee Member
Nickerson, Stephen C. Committee Member
  • nutrient balance
  • nitrogen
  • phosphorus
  • nutrient excretion
  • dairy
Date of Defense 2003-10-14
Availability unrestricted
A 2-yr field study was conducted to reduce nutrient losses from Virginia dairy farms through nutritional and herd management practices. Ten collaborator herds were identified, all at state DHIA average or better for milk yield and days open. Baseline feed samples and ration information were collected for 2 mo and analyzed for phosphorus (P) and nitrogen (N). Feeds were analyzed monthly, and monthly DHIA milk yield, milk composition, milk urea N (MUN), and reproductive data were recorded. Blood and fecal samples were collected from 25 cows/herd every 3 mo to monitor P excretion and blood urea N. Nutrient balances were developed for each farm for N and P at the start of the study and following ration and management changes. Collaborator herds imported, on average, 290% more N and 320% more P onto the farm than was removed through milk, culled animals, crop sales, or manure sales. By following NRC (1989) recommendations, collaborator farms could reduce N inputs by 21% and P inputs by 45%. Minimizing P in purchased feed, purchased feeds/cow, purchased feeds/ha, and total P input could cause significant reductions in P balance for participating collaborator herds. None of the N variables tested (purchased feed, purchased feed/cow, purchased feed/ha, and total N input) provided significant reductions.
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