Abstract

The present study explored the possibility of selection for uniformity of days from calving to first service (DFS) in dairy cattle. A double hierarchical generalised linear model with an iterative reweighted least-squares algorithm was used to estimate covariance components for the mean and dispersion of DFS. Data included the records of 27113 Iranian Holstein cows (parity, 1-6) in 15 herds from 1981 to 2007. The estimated additive genetic variance for the mean and dispersion were 32.25 and 0.0139; both of these values had low standard errors. The genetic standard deviation for dispersion of DFS was 0.117, indicating that decreasing the estimated breeding value of dispersion by one genetic standard deviation can increase the uniformity by 12%. A strong positive genetic correlation (0.689) was obtained between the mean and dispersion of DFS. This genetic correlation is favourable since one of the aims of breeding is to simultaneously decrease the mean and increase the uniformity of DFS. The Spearman rank correlations between estimated breeding values in the mean and dispersion for sires with a different number of daughter observations were 0.907. In the studied population, the genetic trend in the mean of DFS was significant and favourable (-0.063 days/year), but the genetic trend in the dispersion of DFS was not significantly different from zero. The results obtained in the present study indicated that the mean and uniformity of DFS can simultaneously be improved in dairy cows.

Keywords

fertility; hierarchical model; uniformity

Published in

Animal Production Science
2017, Volume: 57, number: 4, pages: 760-766

SLU Authors

• Felleki, Majbritt

  • Department of Applied Animal Science and Welfare, Swedish University of Agricultural Sciences
    
  • Department of Animal Biosciences, Swedish University of Agricultural Sciences
    

Associated SLU-program

Beijer Laboratories in Uppsala


UKÄ Subject classification

Animal and Dairy Science
Genetics and Breeding


Publication identifier

DOI: https://doi.org/10.1071/AN15643

Permanent link to this page (URI)

https://res.slu.se/id/publ/87617