Quantifying the use of and the genetic progress from advanced mating strategies in US dairy herds

Abstract

The use of mating technologies, including genomic testing and sexed semen, has recently increased in the breeding programs of commercial dairy herds, along with the use of beef semen. We aimed to quantify the utilization of advanced mating strategies in US dairy herds and the influence of these strategies on genetic merit. Breeding records (n = 35,124,479) that resulted in successful pregnancies of cows and heifers by semen type (conventional dairy, sexed dairy, and beef) and records of genomic testing of female dairy cattle were extracted from the National Cooperator Database for the years 2008 to 2023. Herds were categorized within year by semen type used and use of genomic testing of heifers and the genetic merit of heifers born in 2023 (n = 678,064) was compared by herd mating strategy. Female dairy cattle in the US are genotyped, on average, at 6 months of age. When the net merit of a genotyped heifer increased by one standard deviation, the odds that she remained in the herd through first lactation increased by 13%. Breeding values of net merit ($1,203) and most of the traits investigated were most favorable in heifers born in herds that used all mating strategies investigated (genotyping of heifers, and a combination of beef, sexed, and conventional semen). Calves born in herds that used a combination of sexed and conventional semen had the least net merit ($532) and generally had the least favorable breeding values across production, fertility, and longevity traits. Results confirm that the incorporation of advanced mating strategies has increased rapidly in US dairy herds. Heifers were more likely to enter the milking herd as their genomic merit increased and herds that incorporated all strategies investigated had the greatest genetic progress.