As we approach the time of year that spring-calving operations will be weaning, selection decisions will be made regarding how many heifers should be developed as replacements, developed for marketing or culled. Likewise, bulls will be selected to be developed as potential herd sires to either use or sell.
These decisions impact marketing success and how we will utilize feed resources, and the accuracy of these selection decisions dramatically impacts how much long-term genetic improvement we will make. With this in mind, using available DNA testing technology can be a cost-effective way to reach our breeding goals faster.
By working with your breed association to order the tests, submitting DNA samples and obtaining the lab results, current DNA testing technology can: verify parentage; determine genotypes for simply-inherited, qualitative traits; and identify genes that have an additive genetic effect on the variation of quantitative, polygenic traits, resulting in more accurate genomically enhanced EPDs.
This information is typically available within a few weeks of when DNA samples are submitted, yielding genetic information that would otherwise take generations of calf crops to obtain.
Determining genotypes for qualitative, simply-inherited traits when dominant/recessive gene action is occurring at a locus can identify homozygous or “carrier” genotypes of animals with the same phenotype.
For example, the horned/polled phenotype where the polled allele is dominant to the horned allele means that polled cattle can be either homozygous polled or heterozygous polled. If our breeding objectives include producing polled calves, parents with the homozygous polled genotype will sire/produce nothing but polled calves. Traits like coat color and most of the identified genetic defects are also simply inherited.
Genomically enhanced EPDs increase the accuracy of selection for traits influenced by thousands of genes. This would include traits like calving ease, weaning and yearling weights, carcass traits and maternal performance.
Breeders should contact their breed association for information and proper procedures for submitting DNA samples. DNA samples can be submitted in the form of blood (in a purple-topped tube or on a DNA card), tissue samples from an ear notch, hair follicles collected from the switch (from cattle weaning age or older) and straws of semen.
Prices for DNA testing have come down dramatically over the past several years. Information on available tests and prices through your breed association should be taken into account when considering the return on investment.
Identifying genetically superior animals early in life not only can increase the effectiveness of selection in your program, but it also provides more reliable estimates of genetic potential to customers purchasing registered, pedigreed seedstock. — Mark Z. Johnson, Oklahoma State University Extension beef cattle breeding specialist
