Author
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POWELL, REX |
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SANDERS, ASHLEY |
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Submitted to: AIPL Research Reports
Publication Type: Government Publication Publication Acceptance Date: 4/1/2002 Publication Date: 4/1/2002 Citation: N/A Interpretive Summary: Standardized lactation averages of cows are useful for indicating trends in production efficiency and describing cow populations. Numbers and standardized yields for lactation records started in 2000 and eligible for use in calculating national genetic evaluations were documented by State and breed. For the second year, protein averages were reported based on true protein rather than crude protein and this is the first year any true protein analysis data have been included. Although the number of Jersey records increased to an all time high, and numbers of Brown Swiss and Milking Shorthorn were nearly unchanged and numbers of records in other breeds (Ayrshire, Guernsey, Holstein, Milking Shorthorn, and Red and White) declined. Average milk yields continue to increase in most breeds, but by less than recent years, and milk yield for Ayrshire and Milking Shorthorn declined slightly. Fat and protein yields were at all-time highs except for Ayrshire and Milking Shorthorn which were steady or dropped slightly (< 1%). Fat percentage in all breeds was fairly steady in recent years as was protein percentage for Ayrshire and Brown Swiss. Protein percentage continued to increase in other breeds, attesting to its increasing market value. Changes in these statistics result from many factors. Genetic change is expected to have a positive effect on yield, whereas feed availability and other operating costs, milk and beef prices, Government programs, and characteristics of herds entering and leaving eligible testing programs can affect production averages in either direction. These statistics are an important reference for comparison of State production levels and trends, and will aid in maintaining the competitive position of the U.S. dairy cattle population worldwide. 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 2002 State and national lactation averages were from year 2000 calvings. This is the second year protein averages have been reported based on true protein rather than crude protein and the first year to include any true protein analysis data instead of all data being converted from crude protein. Component percentages were computed from mean standardized milk and component yields; protein testing is at or near 100% except in California. Numbers and mean standardized yields initiated in 2000 and eligible to contribute to genetic evaluations were documented by State and breed. Number of Jersey records increased to an all time high, and numbers of Brown Swiss and Milking Shorthorn were nearly unchanged, but numbers of records in other breeds (Ayrshire, Guernsey, Holstein, Milking Shorthorn, and Red and White) declined. Component yields increased in all breeds except for Ayrshire and Milking Shorthorn which had steady or slightly decreased (< 1%) yields. Fat percentage in all breeds was fairly steady in recent years as was protein percentage for Ayrshire and Brown Swiss. Protein percentage continued to increase in other breeds, attesting to its increasing market value. Use of these statistics, which provide an important reference for comparison of State production levels, will aid in maintaining the competitive position of the U.S. dairy cattle population worldwide. |
