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Predicted producing value: Formula to account for actual inbreeding in a mating program framework.

S. Westberry

Events

06-24-2020

Abstract:

297
Predicted producing value: Formula to account for actual inbreeding in a mating program framework.
S. Westberry*, C. Heuer, N. Deeb, D. Kendall. STgenetics Navasota, TX.

Increasing herd profitability is essential to dairy producers desiring to withstand the ever-changing dairy industry climate. When optimizing future herd performance based on parent average, a crucial piece of the mating value is missing. The actual relationship of each mating pair needs to be determined and how the resulting inbreeding will affect the producing value of the progeny. In the US, PTA evaluations produced by the CDCB are penalized for expected inbreeding depression based on the Expected Future Inbreeding (EFI) of the animals. The Predicted Producing Value (PPV) formula first removes the inbreeding penalty from sire and dam PTA values. The next step of the formula is to determine the expected progeny inbreeding or actual relationship of each mating pair which utilizes the genomic relationship between all pairs in the proposed matings. The expected inbreeding of the calf can then be multiplied by the inbreeding depression of the selected trait for optimization by utilizing the inbreeding depression factors published by the USDA. In a recent study, STgenetics compared utilizing a parent average PTA optimization mating program and a PPV optimization mating program in Chromosomal Mating. The mating scenario included optimizing Lifetime Net Merit (NM$) across 26,500 females and 100 bulls. The PPVNM$ of the projected progeny was calculated for both optimization strategies so that the 2 results could be compared. The mating that optimized PTANM$ had an average progeny PPVNM$ of 1604, while the mating that optimized PPVNM$ had an average progeny PPVNM$ of 1631. This means that optimizing for PPVNM$ increased the value of the progeny by $27 over the lifetime of the progeny on average. The mating that optimized PPVNM$ also yielded projected progeny with 1.3% lower inbreeding on average compared with the projected progeny from optimizing PTANM$. Utilizing PPV to optimize progeny value in a mating program allows producers to make the most accurate mating decisions based on profitability.

Keywords: inbreeding, mating program, genomic selection.