Submitted to: AIPL Research Reports
Publication Type: Government Publication
Publication Acceptance Date: February 1, 2010
Publication Date: February 1, 2010
Citation: Norman, H.D., Cooper, T.A. 2010. State and National Standardized Lactation Averages by Breed for Cows Calving in 2009. AIPL Research Reports. K2-08 (2-10).
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 2008 calvings. Component percentages were computed from mean standardized milk and component yields. Numbers of lactations initiated in 2008 and eligible to contribute to genetic evaluations, and mean standardized yields were documented by State and breed. Number of calvings for 2008 increased by 4.6 and 7.3% for Holsteins and Jerseys; the other breeds showed a small increase except for Guernsey and Red and Whites. Milk yield was down slightly (-0.1 to -0.8%) for all breeds except Milking Shorthorn (down 2.4%), Guernsey (up 0.2%), and Jerseys (up 0.3%). A failure for milk yield to increase is becoming more common and most likely reflect changes in management strategies considering milk and feed prices and more emphasis on other traits such as health and longevity.