|Wright, Janice - Jan|
Submitted to: American Dairy Science Association Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 7/26/2000
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Characteristics of progeny-test (PT) programs of U.S. artificial- insemination (AI) organizations were examined for changes since 1959 by breed and sampling year: bull age at semen distribution, daughter birth, and daughter calving; sire, dam, and maternal grandsire age at bull birth; and numbers of PT daughters and herds. State trends were documented for PT participation, percentage of cows that were PT daughters, and percentage of PT daughters enrolled in a herdbook. Mean number of bulls progeny tested by major AI organizations annually from 1996 through 1998 was 10 for Ayrshires, 21 for Brown Swiss, 20 for Guernseys, 1,224 for Holsteins, 105 for Jerseys, and 3 for Milking Shorthorns. Mean ancestor ages at bull birth declined across time and were 85 mo for sire, 48 mo for dam, and 136 mo for maternal grandsire for Holsteins recently progeny tested; corresponding ancestor ages for Jerseys were 78, 49, and 131 mo. Mean bull age at semen distribution was 16 mo; mean bull ages at daughter birth and calving declined across time and were 29 and 56 mo (Holsteins) and 32 and 58 mo (Jerseys) for 1992 through 1994. Mean numbers of PT daughters and herds were 62 and 45 for Holsteins and 48 and 30 for Jerseys. For Holstein bulls that entered AI service in 1994, 22% of PT daughters were in California, 13% in Wisconsin, 12% in New York, and 10% in Pennsylvania and Minnesota. Percentage of 1st-lactation cows that were PT daughters has increased over time; was 14% overall in 1998; and varied from 4 to 24% for States with >500 cows. Percentage of PT daughters enrolled in herdbooks was 19% for Holsteins and 79% for Jerseys in 1998. The dairy industry has been able to reduce the PT generation interval by selecting younger parents of PT bulls and by distributing and using semen more quickly.