Joint estimation of (co) variance components and breeding values for mean and dispersion of days from calving to first service in Holstein cow

Ghiasi, Heydar; Felleki, Majbritt

doi:10.1071/AN15643

Forskningsartikel2017Vetenskapligt granskad

Joint estimation of (co) variance components and breeding values for mean and dispersion of days from calving to first service in Holstein cow

Ghiasi, Heydar; Felleki, Majbritt

Sammanfattning

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.

Nyckelord

fertility; hierarchical model; uniformity

Publicerad i

Animal Production Science
2017, volym: 57, nummer: 4, sidor: 760-766

SLU författare

Felleki, Majbritt
- Institutionen för tillämpad husdjursvetenskap och välfärd, Sveriges lantbruksuniversitet
- Institutionen för husdjurens biovetenskaper, Sveriges lantbruksuniversitet

Associerade SLU-program

Beijer Laboratories in Uppsala

UKÄ forskningsämne

Husdjursvetenskap
Genetik och förädling inom lantbruksvetenskap

Publikationens identifierare

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

Permanent länk till denna sida (URI)

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