Use of MOET in Merino breeding programmes: a practical and economic appraisal

Abstract

Commercial application of multiple ovulation and embryo transfer (MOET) technology will be subject to practical constraints and economic rationalism. This study examines use ofMOET in its most profitable arena: to breed stud rams which will disseminate genetic improvement widely through multiplier studs to commercial flocks. A deterministic prediction is used to evaluate schemes based on an open nucleus MOET group within a Merino parent stud, taking account of genetic merit and inbreeding. Selection is based on clean fleece weight with an assumed heritability of 0-4. Embryos are collected at a rate equivalent to 3-45 live lambs per donor. Benefits of MOET were calculated from the discounted expressions of rams sold, and compared with the costs incurred. As the proportion of the flock born from MOET increases, the rate of genetic gain increases rapidly at first, but diminishing returns are observed. The costs ofMOET increase linearly with the number of lambs produced, so the optimum proportion ofMOET lambs is for practical purposes always less than 100%. Some use of MOET was profitable provided the stud sells sufficient stud rams each year. Sensitivity tests found that other parameters had only a small impact on the optimum level ofMOET. In general however, changes which increased the rate of genetic gain (heritability, flock size) or increased its value (wool price, lower discount rate) increased the optimum number ofMOET lambs. The results should provide guidelines to optimum investment in MOET for the wool industry. An across flock genetic evaluation scheme is probably necessary to motivate this investment.

Increased genetic gains in sheep, beef and dairy breeding programs from using female reproductive technologies combined with optimal contribution selection and genomic breeding values

“…Furthermore, if MOET was used and the age of selection candidates decreased, breeding schemes would increase genetic gain by another 9 % [ 3 ]. These gains were similar also in beef and sheep breeding programs, for which MOET was estimated to yield an extra 67 to 100 % of genetic gain for beef [ 4 , 5 ] and 17 to 74 % for sheep [ 6 – 8 ]. However, all these studies agreed that MOET breeding programs would also increase annual rates of inbreeding by up to 110 % compared to traditional mating programs.…”

“…Our study estimated that the benefit of MOET in sheep breeding programs without using GS, was up to 50 % while maintaining the rate of inbreeding at 1 % per generation. Previous studies [ 7 , 8 ] using MOET in sheep breeding programs also predicted such gains but without restricting inbreeding rates. Our beef MOET breeding programs achieved 35 to 43 % more genetic gain than AI programs without GS which was less than previous studies, which reported extra gains of 67 to 138 % [ 7 , 9 , 10 ], but we achieved these gains at the same rate of inbreeding per generation, while rates of inbreeding increased by 87 to 300 % in the aforementioned studies.…”

“…The use of males below their natural or artificial insemination capabilities was needed to maintain diversity without sacrificing too much genetic gain. The concept of reducing inbreeding while implementing reproductive technologies by using more sires under their reproductive capacity has been described previously by Kinghorn [ 33 ], Arendonk and Bijma [ 34 ], Pryce et al [ 14 ] and Lillehammer et al [ 35 ] in dairy, and by Brash et al [ 8 ] in sheep breeding schemes.…”

“…It is clear from previous studies [ 3 – 8 , 10 , 13 , 14 ] that increasing selection intensity for females in breeding programs can significantly increase rates of inbreeding. Optimal contribution selection (OCS) is a method that balances longer-term genetic merit and genetic diversity in breeding populations.…”

Optimizing female allocation to reproductive technologies considering merit, inbreeding and cost in nucleus breeding programmes with genomic selection

“…However, these reproductive technologies have the pitfall to increase the rate of inbreeding (Van der Werf & Marshall, ). There is also a substantial financial cost absorbed by seedstock breeders when carrying out breeding programs that use MOET and/or JIVET (Brash, Wray, & Goddard, ). Therefore, selection decisions in breeding programmes that use reproductive technologies need to account for a variety of considerations to achieve a desirable outcome for seedstock breeders.…”