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Title: SURVIVAL RATES AND PRODUCTIVE HERD LIFE OF DAIRY CATTLE IN THE UNITED STATES

Author
item HARE, E - FORMER AIPL POST-DOC
item Norman, H
item Wright, Janice

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2006
Publication Date: 9/1/2006
Citation: Hare, E., Norman, H.D., Wright, J.R. 2006. Survival rates and productive herd life of dairy cattle in the United States. Journal of Dairy Science. 89(9):3713-3720.

Interpretive Summary: Survival rates and herd life were examined for 13.8 million US dairy cows that calved during 1980 or later. Cows that left the herd for dairy purposes or were from herds that discontinued Dairy Herd Improvement testing were excluded from any calculations that would underestimate their longevity. Mean lactation length for cows without subsequent lactations, i.e. the terminal lactations for those cows, ranged from 205 to 235 d for breed-parity subsets, and were 4 to 30 d longer for second through seventh parity than for first parity. Mean survival rates were about 73% to parity 2, 50% to parity 3, 32% to parity 4, and 19, 10, 5, and 2% to parities 5 through 8, respectively, as compared with survival rates of 78, 57, 40, 27, 17, 10, and 5% that were reported 15 yr ago. Mean number of calvings for Holsteins declined from 3.2 for those first calving in 1980 to 2.8 for those first calving in 1994. Mean numbers of calvings for other breeds first calving in 1994 were 2.9 for Ayrshires and Brown Swiss, 2.4 for Guernseys, and 3.2 for Jerseys. Mean productive herd life (through parity 8) within breed ranged from 28 to 36 mo, which was less than the 35 to 39 mo that was evident 15 yr earlier. All regressions of mean number of parities or mean productive herd life on year were negative. Nevertheless, some of these phenotypic indicators of longevity suggest that the declines have slowed or ended in the most recent years. The percentage of milking cows in their first lactation ranged from 31% for Jerseys to 39% for Guernseys, an increase of 2 to 6% in these breeds from earlier years. These survival and herd life results will help specialists assisting dairy producers on farm management practices make better economic decisions in regard to culling.

Technical Abstract: Survival rates and herd life were examined for 13.8 million US dairy cows that calved during 1980 or later. Cows that left the herd for dairy purposes or were from herds that discontinued Dairy Herd Improvement testing were excluded from any calculations that would underestimate their longevity. Mean lactation length for cows without subsequent lactations, i.e. the terminal lactations for those cows, ranged from 205 to 235 d for breed-parity subsets, and were 4 to 30 d longer for second through seventh parity than for first parity. Mean survival rates were about 73% to parity 2, 50% to parity 3, 32% to parity 4, and 19, 10, 5, and 2% to parities 5 through 8, respectively, as compared with survival rates of 78, 57, 40, 27, 17, 10, and 5% that were reported 15 yr ago. Mean number of parities for Holsteins declined from 3.2 for those first calving in 1980 to 2.8 for those first calving in 1994. Mean numbers of parities for other breeds first calving in 1994 were 2.9 for Ayrshires and Brown Swiss, 2.4 for Guernseys, and 3.2 for Jerseys. Mean productive herd life (through parity 8) within breed ranged from 28 to 36 mo, which was less than the 35 to 39 mo that was evident 15 yr earlier. All regressions of mean number of parities or mean productive herd life on year were negative, and 9 of 10 breed tests were significant statistically. Nevertheless, some of these phenotypic indicators of longevity suggest that the declines have slowed or ended in the most recent years. Milking cows having a single parity ranged from 31% for Jerseys to 39% for Guernseys, an increase of 2 to 6% in these breeds from earlier years.