By Lance Bauer, BBU Director of Breed Improvement
As we begin a new year, it’s a great time to reflect on the last year and plan. As a breed Beefmasters experienced a great year and the demand for our cattle is high, which has been great and a testament to the work that everyone has put in as breeders. As a breed we have seen a trend in the right direction in terms of performance measures and EPDs. As we continue to move forward as a breed it is important to realize that EPDs are the best genetic selection tool that is available. An EPD is an expected progeny difference, or how we expect one animal’s calves to perform on average against another animal’s calves.
When evaluating cattle, it is important to realize that phenotype refers to all observable or measurable traits. This means that all weight and carcass traits as well as any structural or visual evaluation is considered phenotype. Phenotype is made up or genotype and environment, and the simple equation is Phenotype= Genotype + Environment (P=G+E). Genotype is simply the genes an individual possesses. Genotype and environment can both be broken down further into different components. An EPD is designed to take out the environmental effects so that the predictions made are based on the genotype of the animal. This is done because environmental effects are not inherited by offspring.
If an animal is developed in an environment where it has all its nutrient requirements met or exceeded, it should be able to express its genetic potential better. Environment is not altering the genetic potential that we are estimating. I grew up in an environment where I had all the nutrients that I required (plus some), if I had grown up in a different environment with less nutrients, I would probably not be the same size as I am now, but my genetic potential would be the same and my ability to pass on those genetics would be the same. Taking the environment out of the equation is why sometimes animals that have “outstanding” individual performance may not excel in their EPDs, or animals with what some would consider to be lower individual performance have better EPDs.
EPDs also consider all data in the BBU database and all relationships within the database. All animals in the database are related somehow, no matter how distant. Using these relationships helps in the calculation of EPDs by establishing genetic relatedness. EPDs are more accurate than analyzing individual phenotypes and using the phenotypes of parents because these ratios and phenotypes still have an environmental effect to them. Therefore, it is important to have an accurate pedigree and preferably a genotype on animals, to make this portion of EPD calculation more accurate.
As we move into the next year and continue to focus on continual progress, remember that EPDs are the most accurate tool that we have for genetic selection of animals. By using EPDs the environmental effects on phenotype are taken out so that producers can use just the genetic portion of the P=G+E equation in the selection of animals. Environment can play a large role in the observed phenotype, especially if an animal has all it needs to reach its genetic potential vs one that may not have enough to reach its true genetic potential. This is the reason that some people say an animal’s observed phenotype does not match the EPD, the other reason is that all data and relationships are used to calculate EPDs. Remember houses are not built with simple handsaws and hammers anymore, they are built with the best and most efficient tools available, so it is important in cattle breeding to use the best tools available for genetic selection.