Submitted to: AIPL Research Reports
Publication Type: Government Publication
Publication Acceptance Date: 6/19/2006
Publication Date: 6/19/2006
Citation: Norman, H.D., Thornton, L.L. 2006. State and national standardized lactation averages by breed for cows calving in 2004. AIPL Research Report K2-04 (3-06).
Technical Abstract: Means for dairy cow lactation data used in national genetic evaluations and other USDA research are useful for indicating trends and describing cow populations. Breed lactation means are on a 305-day, twice daily milking, mature-equivalent basis from cows contributing to genetic evaluations. Data for State and national lactation averages were from year 2004 calvings. National averages for prior years have been computed to reflect the change from reporting of crude protein to true protein. Component percentages were computed from mean standardized milk and component yields; protein testing is at or near 100% except in California and Nevada. Numbers of lactations initiated in 2004 and eligible to contribute to genetic evaluations, and mean standardized yields were documented by State and breed. Holstein calvings for 2003 were down from last year's slight increases and calvings for Ayrshires, Guernsey, and Red and White continue to decline. Calvings for Jerseys and Holsteins increased 4.7 and 2.1%, respectively. Milk yield was up slightly in all breeds except Milking Shorthorns. Fat and protein production generally showed small increases from the previous year as well.