Submitted to: AIPL Research Reports
Publication Type: Government Publication
Publication Acceptance Date: February 14, 2011
Publication Date: March 1, 2011
Citation: Norman, H.D., Cooper, T.A., Ross Jr, F.A. 2011. State and national standardized lactation averages by breed for cows calving in 2009. AIPL Research Reports. K2-09 (2-11).
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 2009 calvings. Component percentages were computed from mean standardized milk and component yields. Numbers of lactations initiated in 2009 and eligible to contribute to genetic evaluations, and mean standardized yields were documented by State and breed. Number of calvings for 2009 increased by 3.2 and 7.2% for Holsteins and Jerseys; the other breeds showed small declines. A failure for milk yield to increase much is becoming more common and most likely reflect changes in management strategies considering milk and feed prices and more emphasis being placed on other traits such as health and longevity.