The recent and escalating emphasis on gene discovery has major implications for genetic improvement of the NZ sheep industry. However, the long lag phase in the dissemination of new genetic material through current breeding structures is a major impediment to rapid uptake of the improvements. Effective reproductive technologies are considered necessary for achieving the desired rates of dissemination but there is little evidence of their practical and economic values. To provide evidence, a series of modelling exercises were undertaken. This involved defining a particular commercial outcome (advancing the pattern of lamb kill in Otago/Southland by 1 month without changing lambing date), deciding on the relevant genetic trait to achieve this (terminal sires with a 20% increase in mature size), modelling the rate of genetic gain using a number of breeding scenarios that included artificial insemination (AI) and multiple ovulation and embryo transfer (MOET), to determine the time required for sufficient commercial rams to be available to achieve the outcome. Selected scenarios were then chosen for more detailed modelling to ascertain the economic implications to the farm (Otago/Southland lamb finishing farm) and to the industry of adopting the technology. The advancement of the kill pattern by one month was worth $12,714 on the commercial farm. Based on a two-tiered breeding system (stud and commercial) without any reproductive technology it takes 26 years to achieve the outcome (assuming that the animal with this genetic advantage had been identified at the start). The use of AI at the stud level reduced this time by 11 years. The additional use of MOET on stud ewes gave a further reduction in time of 7 years and the application of AI using stud rams at the commercial level an additional 2 years. These results confirm the importance of reproductive technologies in reducing the lag phase in gene dissemination and their value to the industry. There is a need to further refine the efficiency and efficacy of the chosen technologies.

JF, Smith, I Vetharaniam, DG McCall, and HR Tervit

Proceedings of the New Zealand Society of Animal Production, Volume 60, Hamilton, 36-40, 2000
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