%0 Journal Article
%T Estimates of genetic trends for daily milk yield and somatic cell score of primiparous Holstein cattle in Iran
%A Khabat Kheirabadi
%J Journal of Applied Animal Research
%D 2019
%R https://doi.org/10.1080/09712119.2019.1663741
%X ABSTRACT Genetic and permanent environmental correlations between milk yield and somatic cell score (SCS) were estimated. The data set used in this analyse contained a total of 204,438 test-day (TD) observations of milk yield and SCS from 22,903 primiparous daughters of 554 dairy Holstein sires. A multiple-trait random regression TD model was employed in the analyses using the Gibbs sampling method. Obtained results showed that daily heritabilities were highest in the second half of lactation and varied from 0.086 to 0.250 for milk yield and 0.041 to 0.086 for SCS. Undesirable genetic relationships with milk yield were found for SCS with genetic correlations ranging from £¿0.093 to 0.319 that the highest was estimated between SCS days in milk (DIM) 305 and milk DIM 5. Based on these results, we can conclude that the cows with high yield potential in the initial stage of lactation had the highest genetic potential for SCS at the end of lactation. This emphasizes the need for including udder health traits in the breeding goal. However results of this investigation, based on genetic trends, indicate that more emphasis is paid to increase milk yield of Holstein cows in Iran with no or a little emphasis on SCC
%U https://www.tandfonline.com/doi/full/10.1080/09712119.2019.1663741