Optimizing dairy cattle breeding goals to improve production and udder health of crossbred cows

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Abstract

Crossbreeding is known to increase economic profitability by benefiting from heterosis and breed complementarity. Breeding goals (BG) used to select dairy cattle breeds have so far been aimed at improving purebred performance which may be sub-optimal when the goal is crossbred performance. The aim of this study is to compare various purebred BGs in a two-way terminal crossbreeding system for dairy cattle over several generations of crossbreeding. We postulated that differentiating BGs in purebred parental lines could be more efficient to increase crossbred performance. Breeding schemes of Danish Jersey (DJ) and Nordic Holstein (NH) cattle were simulated using real haplotypes of 200 founders sampled from each breed. We simulated a founder population where NH had a higher breeding value for milk production and a lower breeding value for udder health compared to DJ. First, genomic reference populations were constituted for 20 years to predict genomic breeding values with appropriate reliabilities. In year 21-30, a genomic selection scheme for NH and DJ aimed at crossbred performance was simulated. Each year, 2,000 young bulls and 2,000 heifers were genotyped. Out of the young bulls, 50 were selected as sires. Three scenarios were set up to test the hypothesis: (1) a reference scenario resembling the economic values in the present Nordic total merit index for DJ and NH; (2) the same BG in NH as in 1, but a higher value on health in the BG of DJ; and (3) BGs only weighing production in NH and only health in DJ. In year 25-30, a population of crossbred cows was simulated alongside the two pure breeding schemes by mating Jersey cows with Holstein bulls. Purebreds in both nuclei were evaluated both for purebred and crossbred performance. For evaluation of crossbred performance, SNP-BLUP breeding values were estimated by using allele frequencies of the purebred population that an animal was bred to, whereas GBLUP was used for purebred evaluation. Outcomes of this study will be useful to assess the importance of updating BGs in purebred breeding schemes to optimize crossbred performance.
OriginalsprogEngelsk
TitelBook of Abstracts of the 74th Annual Meeting of the European Federation of Animal Science
UdgivelsesstedWageningen
ForlagWageningen Academic Publishers
Publikationsdatoaug. 2023
ISBN (Trykt)978-90-8686-384-6
ISBN (Elektronisk)978-90-8686-936-7
StatusUdgivet - aug. 2023
NavnEAAP Book of Abstracts
Vol/bind29
ISSN1382-6077

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