Starting in August 2017, dairy producers will be able to utilize U.S. genetic evaluations for gestation length when selecting sires. The new trait, gestation length for service sires, is available thanks to the efforts of Jan Wright and Paul VanRaden of USDA’s Animal Genomic and Improvement Laboratory (AGIL). The launch of gestation length follows the introduction of cow livability by CDCB last August and demonstrates the accelerating trend for evaluations on more traits.
Why have dairy breeders and semen marketers asked for genetic evaluations for gestation length? They believe having predicted gestation lengths on service sires can help keep parturitions concentrated in herds with seasonal calving. This information will also help to pinpoint expected calving dates and to aid maternity management in all operations. Gestation length may also be adopted as a correlated trait to improve calving ease.
As this new trait becomes available, it is suggested that producers continue to rely primarily on a composite economic index like Lifetime Net Merit, Cheese Merit, Fluid Merit or Grazing Merit. The choice of an index should depend on a farm’s milk payment situation and their management system. Nevertheless, producers with a seasonal calving operation might consider bypassing those service sires with long predictions for gestation length, as a means of keeping calving frequencies in sync with their nutritional supplies.
Article prepared by Duane Norman, Technical Advisor & Industry Liaison, Council on Dairy Cattle Breeding (CDCB)
1Norman, H.D., J.R. Wright, and R.H. Miller. 2011. Potential consequences of selection to change gestation length on performance of Holstein cows. J. Dairy Sci. 94 (2):1005-1010.
Animal Genomic and Improvement Laboratory (AGIL) is part of Agricultural Research Service (ARS) of the United States Department of Agriculture (USDA)