A METHOD THAT PREDICTS THE GENETIC COMPOSITION AND INBREEDING OF THE FUTURE AUSTRALIAN DAIRY HERD

摘要

A method that predicts future inbreeding (F), using information on the current cow population, semen use (mating decisions) and progeny test (PT) bulls, is described. The genetic composition of the future cow herd of Australian Holstein-Friesian (HF)(upto 9 years into the future) is predicted. There are about 650,000 cows with both parents known and about 450,000 cows with four grandparents known. The F of cows born in 2000 is 0.014 (known parents) or 0.017 (known grandparents). The average F of HFcattle born in 2003 was estimated to be about 0.02 and is predicted to reach 0.03 in animals that are expected to be born in 2008. The average F of the prospective progeny of the top 10 bulls (on estimated breeding value) randomly mated to active cows of2004 was 0.024 and was reduced to 0.012 when bulls are mated selectively to minimise F. The information on the genetic composition of the current and future cow herd can be used to identify potential bull sires and/or young bulls that can be used to minimise future F. This can be combined with the information on genetic merit when breeding companies decide to cull bulls after PT or when selecting bull sires.