|NORMAN, H - Council On Dairy Cattle Breeding|
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2017
Publication Date: 6/24/2017
Citation: Hutchison, J.L., Van Raden, P.M., Cole, J.B., Fok, G.C., Norman, H.D. 2017. Bull fertility evaluations for Angus service sires bred to Holstein cows. Journal of Dairy Science. 100(Suppl. 2):242(abstr. T45).
Technical Abstract: Sire conception rate (SCR), a phenotypic evaluation of service-sire fertility implemented in August 2008, is based on data from the most recent 4 years, conventional-semen breedings up to 7 services, and cow parities 1 through 5. Many US dairy cows are now being bred to Angus sires because beef prices are high and there is a surplus of dairy heifers in many herds. The same procedure was used to derive SCR for Angus sires bred to Holstein (HO) cows, with service-sire inbreeding and expected inbreeding of resulting embryo set to 0 because pedigree data were unavailable. Service-sire age was combined into 3 groups (1.8 to 4.5; 4.6 to 7.5; and > 7.5 yr). A total of 97,987 breedings were available and included observations on 947 service-sires and 64,061 cows. A mean conception rate of 30% was observed (46% standard deviation), compared to 32% for breedings with a HO cow mated to a HO sire. Publishable Angus bulls were required to have 100 total matings, 10 matings in the most recent 12 months, and breedings in 5 or more herds. Mean SCR reliability was 56% for 95 publishable bulls, with a maximum reliability of 97% based on 8,840 breedings. Average SCR was near 0 (on an Angus base), with a range of -3.4 to 3.3. There were a small number of breedings for other beef breeds, including Charolais, Gelbvieh, Hereford, and Limousin (557, 190, 1642, and 141 breedings, respectively). Breedings to HO heifers were also examined. A total of 8,446 breedings were available consisting of 399 service-sires and 6,570 cows. A mean conception rate of 49% was observed (50% standard deviation), compared to 57% for breedings with a HO heifer mated to a HO sire. This difference is explained by HO sires being used for early services, with an average service number of 1.77 services. Angus sires are used mainly for later services of problem breeders and have an average service number of 2.90 services. Mating dairy cows to beef bulls may be profitable if the calf price is higher, fertility is better, or if practices such as sexed semen, genomic testing, and improved cow productive life allow herd owners to produce both higher quality dairy calves for replacement and beef calves for market.