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

Abstract

Female reproductive technologies such as multiple ovulation and embryo transfer (MOET) and juvenile in vitro fertilization and embryo transfer (JIVET) have been shown to accelerate genetic gain by increasing selection intensity and decreasing generation interval. Genomic selection (GS) increases the accuracy of selection of young candidates which can further accelerate genetic gain. Optimal contribution selection (OCS) is an effective method of keeping the rate of inbreeding at a sustainable level while increasing genetic merit. OCS could also be used to selectively and optimally allocate reproductive technologies in mate selection while accounting for their cost. This study uses stochastic simulation to simulate breeding programmes that use a combination of artificial insemination (AI) or natural mating (N), MOET and JIVET with GS. OCS was used to restrict inbreeding to 1.0% increase per generation and also to optimize use of reproductive technologies, considering their effect on genetic gain as well as their cost. Two Australian sheep breeding objectives were used as an example to illustrate the methodology-a terminal sire breeding objective (A) and a dual-purpose self-replacing breeding objective (B). The objective function used for optimization considered genetic merit, constrained inbreeding and cost of technologies where costs were offset by a premium paid to the seedstock breeder investing in female reproductive technologies. The premium was based on the cumulative discounted expression of genetic merit in the progeny of a commercial tier in the breeding programme multiplied by the proportion of that benefit received by the breeder. With breeding objective B, the highest premium of 64% paid to the breeder resulted in the highest allocation of reproductive technologies (4%-10% for MOET and 19%-54% for JIVET) and hence the highest annual genetic gain. Conversely, breeding objective A, which had a lower dollar value of the breeding objective and a maximum of 5% mating types for JIVET and zero for MOET were optimal, even when highest premiums were paid. This study highlights that the level of investment in breeding technologies to accelerate genetic gain depends on the investment of genetic improvement returned to the breeder per index point gain achieved. It also demonstrates that breeding programmes can be optimized including allocation of reproductive technologies at the individual animal level. Accounting for revenue to 80 | GRANLEESE Et AL. | 81GRANLEESE Et AL.

Intensified Use of Reproductive Technologies and Reduced Dimensions of Breeding Schemes Put Genetic Diversity at Risk in Dairy Cattle Breeds

“…In addition, increasing the number of female donors from 150 to 300 always resulted in significantly higher ∆ G TBV regardless of the intensity of RT use. These results were all consistent with the findings of previous studies [ 9 , 10 , 19 , 20 ]. Instead, changes in the number of female donors did not seem to have any consistent effect on inbreeding rate, ∆ F ROH ; this was also in agreement with a previous report that increasing the intensity of RT use (i.e., the number of calves per female donor) had a greater impact on ∆ F ROH than increasing the number of female donors [ 9 ].…”

“…Our results were obtained from simulations of a breeding scheme that used random mating and that imposed constraints on the number of calves per bull and female donor that could become bulls or donors themselves. With this design, we might have overestimated genetic gains and inbreeding rates in comparison with breeding schemes that use avoidance mating [ 45 ] or optimal contributions (OC) [ 19 , 46 , 47 ]. The recommendations provided by OC algorithms can be quite useful, as this technique aims to produce a list of individuals for breeding in which global relatedness is minimized.…”

“…In large dairy cattle breeds, RTs such as multiple ovulation and embryo transfer (MOET) and ovum pick-up and in vitro fertilization (OPU-IVF) are commonly used. In combination with genomic selection, RT appears to be very beneficial for genetic gain in dairy breeds [ 19 , 20 , 21 , 22 , 23 ]. The increased genetic gain associated with RT is due to an intensification in the use of the best females, with higher selection intensity [ 24 ], and to a reduction in the intervals between generations.…”

Genotyping strategies of selection candidates in livestock breeding programmes

“…However, bulk amounts of MOET and/or JIVET may not be practical or affordable at nucleus level, but could be considered to contribute to some part of a nucleus breeding programme. Granleese, Clark, Kinghorn, and Werf () demonstrated that optimal contribution selection can consider the cost of respective reproductive technologies in the objective function when selecting female candidates. Commercial mating programmes like Matesel (Kinghorn, ) can help optimize matings when using different combinations of reproductive technologies with natural mating and/or artificial insemination.…”

Review: Environmental impact on early embryonic development in the bovine species

“…The additional harvesting of embryos using multiple ovulation and embryo transfer (MOET) programs in cattle offers an extensive platform for introducing valuable breeding steps and thus significantly controlling the effects on breeding quality and progress. Thus, assisted reproduction techniques (ARTs) open up not only classical applications but also innovative approaches such as evaluation of the genomic breeding value and genome editing (Cornelissen et al, 2017;Fujii et al, 2017, Granleese et al, 2018, Jaton et al, 2018, Menchaca et al, 2018, Georges et al, 2019. Since the recovery of embryos by means of superovulation is associated with limitations, significantly more embryos could be provided with the development and establishment of in vitro production (Galli et al, 2003).…”