THE EFFECT OF ALTERNATIVE MATING DESIGNS AND SELECTION-STRATEGIES ON ADULT MULTIPLE OVULATION AND EMBRYO TRANSFER (MOET) NUCLEUS BREEDING SCHEMES IN DAIRY-CATTLE

The impact of alternative mating designs and selection strategies on rates of response and inbreeding in closed adult multiple ovulation and embryo transfer (MOET) nucleus breeding schemes in dairy cattle was investigated by Monte Carlo simulation. Results were compared with those from schemes using hierarchical mating designs and with one male chosen at random from each selected male full sib group. The use of more than one male from each selected sibship reduced inbreeding rates by 24-34% because more sires were used. With one male chosen from each selected sibship, factorial mating designs increased response rates by up to 13% because the number of sibships, and hence the number of male candidates, was increased. Finally, factorial sibship schemes, which employed both of these strategies, increased response rates by 5-14% and, with one exception, reduced inbreeding rates by 14-30%.