Title: Genetic evaluation of stillbirth in US Brown Swiss and Jersey cattle Authors
|Yao, Chen -|
|Weigel, Kent -|
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 4, 2013
Publication Date: April 1, 2014
Repository URL: http://handle.nal.usda.gov/10113/58868
Citation: Yao, C., Weigel, K.A., Cole, J.B. 2014. Genetic evaluation of stillbirth in US Brown Swiss and Jersey cattle. Journal of Dairy Science. 97(4):2474-2480. Interpretive Summary: Stillbirth is an economically important calving trait. Currently, the US computes genetic evaluations only for Holsteins. The existing sire-maternal grandsire threshold model was modified to support a multi-breed genetic evaluation for Brown Swiss, Holstein, and Jersey bulls. Average predicted transmitting abilities for sire and daughter stillbirth of Brown Swiss, Jersey, and Holsteins bulls were 4.8% and 6.5%, 5.6% and 6.5%, and 5.5% and 7.7%, respectively, with average reliabilities of 45% to 50%. Favorable (decreasing) phenotypic and genetic trends were observed. Crossbreeding of Brown Swiss and Jersey bulls with Holstein cows is an effective way of lowering the stillbirth rate in the population.
Technical Abstract: Stillbirth (SB) has been associated with reduced milk yield, compromised reproductive performance, and decreased dam longevity. Genetic evaluations for stillbirth were initiated in 2006 for Holsteins (HO) in the US, but evaluations for Brown Swiss (BS) and Jersey (JE) cattle were not feasible at that time due to insufficient data. In this study, a sire-maternal grandsire threshold model was used to perform a multi-breed genetic evaluation for BS, HO, and JE stillbirth using 14 million records including both purebred and crossbred calvings. Phenotypically, the percentage of stillbirths (%SB) were 3.7% in JE, 5.1% in BS, and 6.3% in HO. Compared to HO, crossbred calvings of BS and JE bulls with HO cows lowered %SB by 1.5% and 1.2%, respectively. In general, %SB increases considerably as calving difficulty increases in both HO and BS. The relationship in JE was consistent with BS and HO for calving ease scores of 1 (no difficulty) through 3 (needed assistance), but scores 4 (considerable force) and 5 (extreme difficulty) had similar stillbirth rates as score 3. Stillbirth rates were the highest in primiparous cows regardless of calf sex, and were lower in multiparous dams. Male calves in HO had higher %SB than female calves. Stillbirth rates of female calves in JE, however, were higher than male calves, and female calves from BS purebred calvings also had higher %SB in later parities. Favorable (decreasing) phenotypic and genetic trends from 1999 to 2009 were observed in all three breeds. Heterosis for BS and JE SB was -0.026 and -0.149 on the underlying scale, which corresponds to effects on service sire (SSB) and daughter (DSB) PTA of -0.3% and -0.5% in BS, and -1.5% and -2.7% in JE. Overall, BS had the most desirable SSB PTA, with an average of 4.8%, compared to 5.6% for JE and 5.5% for HO. The average DSB PTA in JE and BS were 6.5% in both cases, and 7.7% in HO. Mean reliabilities of SSB and DSB in three breeds ranged from 45% to 50%. Multi-breed genetic evaluation including BS, JE, and HO records is feasable. Brown Swiss and JE have more desirable PTA for SSB and DSB as compared to HO, and crossbreeding BS and JE bulls with HO cows is an effective way to lower stillbirth rates in the population.