Author
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POWELL, REX |
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Submitted to: NCDHIP Handbook
Publication Type: Government Publication Publication Acceptance Date: 4/21/1998 Publication Date: N/A Citation: N/A Interpretive Summary: Standardized lactation averages for cows in official dairy recordkeeping programs are useful for indicating trends and describing cow populations. Numbers and standardized yields for lactation records started in 1996 and eligible for use in calculating genetic evaluations were documented by state and breed. Numbers of records generally decreased from 1994 to 1996 with losses of 22% for Guernseys, 18% for Red and Whites, 16% for Ayrshires, and 5 to 9% for Brown Swiss, Holsteins, Jerseys, and Milking Shorthorns. Losses since 1990 are 49% for Guernseys and 37% for Ayrshires. Other breeds declined by 1 to 9% over those 6 years. Average milk yields were up by 6 to 13% across breeds since 1990 but only 0 to 2% since 1994 except for a decrease of 3% for Red and Whites. Fat percentages tended to increase slightly from the decline from 1992 to 1994 except for Jerseys, for which fat percentage continued to decline. Protein percentages generally decreased slightly. These statistics provide an important reference for comparison of state production levels and trends, and their use 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 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 herds enrolled in official and some owner- sampler test plans that include fat testing. Lactation records also were standardized for age-parity, month of calving, and previous dry period using adjustment procedures implemented in January 1995. Records with less than 305 days were projected to 305 days. Component percentages were computed from mean standardized milk and component yields; protein testing is at or near 100% except in California. Only information for a cow's first 5 lactations was included, but first-lactation data were required for any other information to be included. Numbers and mean standardized yields initiated in 1996 and eligible to contribute to genetic evaluations were documented by state and breed. Numbers of records generally decreased from 1994 to 1996 with losses of 22% for Guernseys, 18% for Red and Whites, 16% for Ayrshires, and 5 to 9% for Brown Swiss, Holsteins, Jerseys, and Milking Shorthorns. Losses since 1990 are 49% for Guernseys and 37% for Ayrshires. Other breeds declined by 1 to 9% over those 6 years. Average milk yields were up by 6 to 13% across breeds since 1990 but only 0 to 2% since 1994 except for a decrease of 3% for Red and Whites. Fat percentages tended to increase slightly from the decline from 1992 to 1994 except for Jerseys, for which fat percentage continued to decline. Protein percentages generally decreased slightly. |
