|Cushman, Robert - Bob|
Submitted to: Midwestern Section of the American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2011
Publication Date: 3/1/2012
Citation: Kill, L.K., Mousel, E.M., Cushman, R.A., Perry, G.A. 2012. Effect of heifer calving date on longevity and lifetime productivity [abstract]. Journal of Animal Science. 90 (Supplement 2):131 (Abstract #340P). Interpretive Summary:
Technical Abstract: Longevity and lifetime productivity are important factors influencing profitability. Heifers that conceive earlier in the breeding season will calve earlier in the calving season and have a longer interval to rebreeding. Calves born earlier in the calving season will also be older and heavier at weaning. Longevity data were collected on 2,195 heifers from producers in South Dakota Integrated Resource Management groups. Longevity and weaning weight (ww) data were collected on 16,549 individual heifers at the USMARC. Data were limited to heifers that conceived during their 1st breeding season. Heifers were grouped into 21 d calving groups. Heifers were determined to have left the herd when they were diagnosed not pregnant at the end of the breeding season. Heifers that left the herd for reasons other than reproductive failure were censored from the data. Heifers that calved with their first calf during the first 21 d period of the calving season had increased (P<0.01) longevity compared to heifers that calved in the second 21 d period, or later. Average longevity for South Dakota heifers that calved in the 1st or later period was 5.1±0.1 and 3.9±0.1 yr, respectively. Average longevity for USMARC heifers that calved in the 1st, 2nd, and later period was 8.2±0.3, 7.6±0.5, and 7.2±0.1 yr, respectively. Calving period influenced (P</=0.03) ww of the 1st, 2nd, 3rd, 4th, and 5th calf; but did not influence the ww of the 6th (P=0.24), 7th (P=0.30), 8th (P=0.30), and 9th (P=0.37) calf. In addition, calving period influenced total pounds weaned and mean ww (P<0.01), with heifers that calved during the 1st period having increased ww, total pounds weaned, and mean ww compared to heifers calving in the 2nd or later period, and heifers calving during the 2nd period having increased ww, total pounds weaned, and mean ww compared to heifers calving later. In summary, heifers that calved early in the calving season with their first calf had increased longevity and pounds weaned compared to heifers that calved later in the calving season. USDA is an equal opportunity provider and employer.