In addition to production decisions, genomic results also provide important genetic information that assists in making successful matings, including:
HAPLOTYPE IDENTIFICATION – Several haplotypes, which are sections of DNA inherited as a group, have been identified that negatively affect fertility. In Holsteins, they are HH1, HH2 and HH3. One has been identified in Brown Swiss (BH1) and one in Jerseys (JH1). These haplotypes are fairly common within their respective breeds, so culling based on their presence is not advised. But Hoffman says it is important to avoid breeding a female haplotype carrier to a haplotype-carrier bull, which would increase the likelihood of failed conception or early embryonic loss by about 25 percent. “Lost pregnancies are very expensive in heifers,” says Hoffman. “Using genomic information is an easy way to avoid a widespread problem in the industry.”
INBREEDING AVOIDANCE – Inbreeding is a silent scourge that can rob dairies of milk production potential, reproductive performance, and calf health and vigor. It also increases the risk potential for recessive genetic disorders. Genomic reports include the percent of homozygous genes an animal carries, meaning the animal received the same gene from both parents. Heifers identified as moderately to highly inbred can either be culled or carefully mated to diversify the genetic makeup of their offspring.
Jeff Ziegler, genomic program manager for Select Sires in Plain City, Ohio, acknowledges that genomics potentially could accelerate inbreeding. “Based on genomic data, we’re winnowing down the best of the best fairly quickly,” he says. “If we’re not careful, we could rapidly breed ourselves into a very narrow gene pool.”
To address this issue, Select Sires studied the diversity strategies of other genetics-based industries, including the seed corn industry. They recognized the importance of creating bloodlines that are not very closely related. Those bloodlines then can be crossed to reap the benefits of hybrid vigor.
The commercial result of those efforts is a Holstein sire genetic development program from Select Sires called StrataGENTM. For several years, Select Sires has been mating and sorting bulls — both daughter-proven sires and young sires — specifically designed to fit one of five distinct bloodlines. Herds then can apply the information to a three- to five-line rotation over multiple generations using a simple, color-coded system.