Submitted to: Journal of Dairy Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/19/2004
Publication Date: 4/1/2005
Citation: Cole, J.B., Goodling Jr, R.C., Wiggans, G.R., Van Raden, P.M. 2005. Genetic evaluation of calving ease for Brown Swiss and Jersey bulls from purebred and crossbred calvings. Journal of Dairy Science. 88(4):1529-1539. Interpretive Summary: Dairy producers are increasingly interested in crossbreeding as a tool to improve calving ease, health, fertility, and longevity. The feasibility of providing a routine calving ease evaluation for Brown Swiss and Jersey breeds was studied. Holstein and Brown Swiss bulls produce calves that are born with similar degrees of difficulty. Brown Swiss bulls appear to produce daughters that give birth more easily than those of Holstein bulls. Jerseys had very little calving difficulty and thus a very small range of evaluations. The national genetic evaluation system for calving ease was extended to include purebred and crossbred matings of Brown Swiss bulls.
Technical Abstract: The objective of this study was to examine the feasibility of implementing routine national calving ease (CE) genetic evaluations of Brown Swiss (BS) and Jersey (JE) sires that include records of crossbred calvings. Records were available for 11,793 BS calvings, 3431 BS-sired crosses, 65,293 JE calvings, and 7090 JE-sired crosses. Evaluations were performed for each breed using only purebred calvings and using both purebred and crossbred calvings. In the latter evaluations, the sire-maternal grandsire model used for the routine evaluation of Holstein (HO) CE was modified to include a fixed breed composition effect to account for differences between purebred and crossbred calvings. Results show that JE cows had very little calving difficulty and thus a very small range of evaluations, suggesting that a routine JE evaluation would be of little value. Results from the BS evaluations suggest a routine evaluation would provide BS breeders with a useful tool for genetic improvement. Further examination of data shows many BS calvings are in mixed herds with HO calvings. As a result, a joint evaluation for BS and HO bulls was developed. The BS data showed that there is similar genetic variability as found in the HO population which suggests implementation of a routine evaluation including BS CE would be of value. It appears BS bulls may produce daughters with superior maternal calving ability as compared to HO. Validation of the joint evaluation was performed by comparing results from separate BS and HO evaluations. Solutions were comparable to results from the routine HO-only evaluation. Correlations among solutions and evaluations showed HO evaluations were not adversely affected by BS data and BS sires were re-ranked as compared to the BS-only evaluation. The joint evaluation will be implemented in February, 2005.