48 NEBRASKA CATTLEMAN March 2026 Environment Ofsspring Performance No GxE Only “additive” genetic differences Environment Offspring Performance GxE (Reranking) Environment-dependent performance Environment Offspring Performance GxE (No reranking) Environment-dependent performance Environment Offspring Performance Robustness Genetic Tools for Breeding Better Adapted Cattle TROY ROWAN, PH.D. | ASSISTANT PROFESSOR – BEEF CATTLE GENOMICS, UNIVERSITY OF TENNESSEE There is no such thing as an average environment! While it is easy enough to calculate an average environment, it is unlikely to be representative of any actual environment in which we’re managing our cattle. That means that there is no one-size-fits-all cow that will function optimally across all environments. These are ideas that breeders have known for centuries, leading to the development of locally adapted breeds that can address environmental challenges, stressors and local needs. This even held as we brought new breeds into the United States, where breeders largely exchanged genetics locally or regionally. In a way, this self-selected for animals adapted to the local environment. Animals that were maladapted to, say, elevation were less likely to be retained as replacements or used as herd bulls. The widespread use of artificial insemination has completely changed this situation. Commercial herds and seedstock breeders are no longer restricted to using genetics sourced from their neighbors. We can bring Nebraska genetics to Tennessee without any real hurdles. The progress enabled by artificial insemination has had an enormous positive impact on the industry. Breeders have access to better genetics than ever before. That said, we run an increased risk of placing genetics in situations where they cannot express their full potential. The importance of artificial insemination will continue to grow in the industry. Still, it may negatively affect the local adaptability of our herds if we don’t work to identify animals whose genetic potential can be expressed in the environments we need it to be expressed in. Genotype-by-Environment Interactions The idea that different genotypes perform better or worse depending on the environment they are in is called genotype-by-environment (GxE) interaction. In other words, when GxE variation affects a trait, an animal’s genetic potential will depend on the environment they are in. The figures within this article shows four different instances of two “genotypes’” performances across an environmental stressor. CONTINUED ON PAGE 50 PRODUCTION
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