University of Georgia
College of Agricultural and Environmental Sciences

Conception rate for beef service sires

The adoption of beef bull semen in dairy herds presents advantageous opportunities for farmers. Dairy farmers rely on replacement females to be of equal or greater value than those of the previous generation. A breeding strategy that is growing in popularity is to use sexed dairy semen on the best females to generate replacement heifers and to use beef semen on the remainder. When used, sexed semen yields the predetermined calf sex with about 90 percent probability, minimizing the chance of an unwanted male calf. Females not selected to produce the next generation of replacement heifers are increasingly being bred to beef bulls to produce crossbred calves for beef production. With the increasing use of beef semen in dairy herds, evaluating fertility of beef bulls becomes of utmost importance. UGA animal and dairy scientists developed a measure of sire conception rate for beef service sires. This meaure evaluates the effect of bulls on the breeding outcomes (success or failure), while taking into account the mating cows‘ effects. As the beef sire conception rate is based on the approach used for evaluating dairy bull fertility, dairy farmers can now compare sire conception rates between dairy and beef bulls. They found that fertility levels between beef and dairy service sires are comparable, although beef sires are more frequently used in cows known to be problem breeders. They created a toll to evaluate beef service sire fertility that is comparable to dairy service sire fertility, and will help dairy producers to select the best beef sires to reduce breeding failure. Mating beef bulls to dams not producing replacement heifers will result in more valuable crossbred calves for beef output.

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