Browsing by Subject "valintaero"

Genomic selection was adopted by dairy cattle breeding industry approximately ten years ago. The aim of this study was to compare realized selection differentials and generation intervals of ayrshire and holstein cows in two selection paths, sires of cows and dams of cows in breeding programs that were based either on progeny testing or genomic selection. Progeny testing was characterized by cow calves that were born in 2008–2009 and genomic selection by calves that were born in 2015–2016. These age groups were split further into groups of first calving heifers that had calved during 2010–2011 or 2017–2018. Data for this study was received from Faba co-op and analysis of the data was performed with R-software. Selection differentials in the selection path of dams of cows increased by 1,55 NTM units in ayrshire and 1,69 NTM units in holstein breed between the age groups. Selection differentials of the dams of the first calving heifers were a bit higher than that of the dams of the cow calves. Selection differentials in the sires of cows path were 4,83 NTM units higher in ayrshire and 1,98 NTM units higher in holstein in the breeding program based on genomic selection than progeny testing. Generation interval reduced from 5,3 to 3,3 years in ayrshire and from 5,0 to 3,1 years in holstein breed. Biggest reduction in generation interval was observed in the selection path of sires of bulls, where the generation interval reduced 61 % in ayrshire and 65 % in holstein breed. Sires of cows path showed 31 % reduction in ayrshire and 32 % reduction in holstein and dams of bulls path 45 % reduction in ayrshire and 30 % reduction in holstein breed. Transfer from breeding program based on progeny testing to breeding program based on genomic selection had no influence on the generation interval of the dams of cows path. Selection differentials in the sires of cows path were higher in holstein than in ayrshire in both progeny testing and genomic selection schemes and they increased more in ayrshire breed. Selection differentials of the sires and dams of first calving heifers were a bit higher than of the dams and sires of all cow calves. As expected, genomic selection has reduced generation interval and the biggest change has occurred in sires of bulls path.