MOET RESULTS FROM A DISPERSED HYBRID NUCLEUS PROGRAM IN DAIRY-CATTLE

A dispersed hybrid MOET nucleus project was implemented in the Canadian dairy industry. Embryo yield, pregnancy rate, and effects of management and selection practices are reported. Repeatability of viable embryo yield was 0.31. Average viable embryo yield was 6.85 (s.e. 5.35) embryos per collection, with average pregnancy rates of 0.58, 0.46 and 0.51 for grade 1 fresh, frozen, and split embryos, respectively. Of the donors selected, 80% produced enough embryos to form a family of at least 15 offspring. Based on observed results, expectations of family size and structure and generation intervals were calculated. Only 10% of completed families are expected to result in less than three milking daughters. Generation interval for sib-tested sires was 58 months of age under practical field conditions, which was shorter by a factor of 0.1 9 than a traditional progeny test but longer than original theoretical estimates by a factor of 0-32. Realized selection intensities for a total merit index were 2.22 for sires and 3.77 for dams of embryos. Accuracies of selection for sires and dams were 0.93 and 0.73 respectively. To improve the scheme, use of more fresh embryos, embryo splitting and less delay in transferring frozen embryos are recommended.