other authors

The rate of genetic improvement in Ireland up until the mid-80’s was low (approx. 0.5 % per year) compared to North America where genetic merit for milk production was increasing by 1.5 % per year (Funk, 1993). Since 1985 the rate of genetic improvement increased markedly to about 1.5 % per year in 1992 (Coffey, 1992). This high rate of genetic progress has mostly been achieved through the importation of North American and European genetics. The relative merit of these sires has been obtained from the performance of their progeny in systems of milk production which differ greatly from those operated in Ireland. The term “high genetic index ” (HGI) is used to describe a cow, which as a result of selection, is generally predisposed to produce significantly more milk than a cow of lower merit status. Studies from New Zealand have shown that cows of high “genetic index ” at pasture, produce more milk (20 to 40%), consume more herbage (