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Title: STATE AND NATIONAL STANDARDIZED LACTATION AVERAGES BY BREED FOR COWS CALVING IN 2003

Author
item Sanders, Ashley
item POWELL, REX - 1201-01-00

Submitted to: AIPL Research Reports
Publication Type: Government Publication
Publication Acceptance Date: 3/7/2005
Publication Date: 3/7/2005
Citation: Sanders, A.H., Powell, R.L. 2005. State and national standardized lactation averages by breed for cows calving in 2003. AIPL Research Report K2-03(2-05). Available: http://aipl.arsusda.gov/publish/dhi/current/lacavx.html

Interpretive Summary:

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 year 2005 State and national lactation averages were from year 2003 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 2003 and eligible to contribute to genetic evaluations, and mean standardized yields were documented by State and breed. Both Ayrshire and Holstein calvings for 2003 were down from last year's slight increases and calvings for Guernsey, and Red and White continue to decline. Calvings for Jerseys and Milking Shorthorns continued to increase. For the second year, milk yield was essentially unchanged. Fat and Protein production were also generally unchanged from the previous year. The leveling off of average yields may reflect changes in management strategies and increased genetic emphasis on other traits affecting profitability such as health and longevity. Interpretation of trends in lactation averages should be made in view of other changes affecting profitability.