Skip to main content
ARS Home » Research » Publications at this Location » Publication #71134
Title: STATE AND NATIONAL STANDARDIZED LACTATION AVERAGES BY BREED FOR COWS ON OFFICIAL TEST, CALVING IN 1994

Author
item POWELL, REX

Submitted to: Oxygenic Photosynthesis: The Light Reactions
Publication Type: Book / Chapter
Publication Acceptance Date: 5/16/1996
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 1994 and eligible for use in calculating genetic evaluations were documented by state and breed. Numbers of records generally decreased from 1992 to 1994 with a 22% loss for Guernseys, small decreases for Ayrshires and Brown Swiss, little change for Holsteins and Jerseys, and small increases for Milking Shorthorns and Red and Whites. Average yields for all breeds increased from 1992 to 1994 by 2 to 6%. Fat percentages tended to be lower with a decrease of .05% for Jerseys. Protein percentages changed little. Use of these statistics 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 test plans that include fat testing. Lactation records also were standardized for age- parity, month of calving, and previous days open using adjustment procedures implemented in January 1995. Component percentages were computed from mean standardized milk and component yields; protein testing is at or near 100% except in California and Nevada. Records in progress and other records short of 305 days were projected to 305 days. 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 1994 and eligible to contribute to genetic evaluations were documented by state and breed. Numbers of records generally decreased from 1992 to 1994 with a 22% loss for Guernseys, small decreases for Ayrshires and Brown Swiss, little change for Holsteins and Jerseys, and small increases for Milking Shorthorns and Red and Whites. Mean yields for all breeds increased from 1992 to 1994 by 2 to 6%. Fat percentages tended to be lower with a decrease of .05% for Jerseys. Protein percentages changed little.