Browsing by Subject "udder traits"

Genetic parameters and relationships were estimated for production, herd life, and udder traits for Finnish Ayrshire and Holstein cows. Data consisted of 25,521 Ayrshire cows and 7703 Holstein cows, born from 1994 to 2005. The estimated production traits were first lactation milk yield and lifetime milk yield, estimated herd life traits were total days in milk and number of lactations. The estimated udder traits were fore attachment, fore teat placement, median suspensory, total udder, rear attachment width, rear attachment length, rear teat placement, balance, teat length, teat thickness, and udder depth. Heritabilities and genetic correlations between traits were calculated by REML using the DMU software. Heritabilities for lifetime milk and herd life traits were near zero. Heritability for first lactation milk was 0.25 for Ayrshire and 0.19 for Holstein. The estimates of heritabilities for udder traits were mainly low to moderate ranging from 0.15 to 0.32. Teat length (Ayrshire 0.32; Holstein 0.29) and udder depth (Ayrshire 0.30; Holstein 0.31) had the highest heritabilities. The genetic correlations between first lactation milk and lifetime milk were moderate (Ayrshire 0.37; Holstein 0.47). Teat length and thickness had a negative genetic correlation to lifetime milk and both herd life traits. The highest positive genetic correlations were between udder depth and herd life traits and between total udder and herd life traits in Ayrshire, ranging from 0.35 to 0.37. Direct selection on lifetime and herd life traits would not be effective because of the low heritabilities and, because longer generation intervals are associated with these traits. Alternatively, progress can be made in herd life traits by putting selection emphasis on udder depth and avoiding thick and long teats.