A recent analysis of DNA data from 60 years’ worth of frozen bull semen has shown that, while the genes for fertility and productivity have improved over time, genes that enable adaptation to environmental stresses have faded among cattle.
The results of this study, published recently in PLOS Genetics, indicate that, as a result of selective breeding for specific desirable physical traits, today’s herds are losing the genes that enable them to adapt to changes in environment, such as increased temperature or humidity, higher altitude or different types of grass.
Study co-author Jared Decker is an associate professor and Wurdack Chair in Animal Genetics in the College of Agriculture, Food and Natural Resources at the University of Missouri.
“We can see that, for example, historically cows in Colorado are likely to have adaptations that ease the stress on their hearts at high altitudes,” explained Professor Decker. “But if you bring in bulls or semen from a different environment, the frequency of those beneficial adaptations is going to decrease. Over generations, that cow herd will lose advantages that would have been very useful to a farmer in Colorado.”
Professor Decker and his team recognize that this is not the fault of cattle farmers since they have no cost-effective genetic test to determine whether the bull they choose to inseminate their cows is adapted for the environment where the herd resides and the calves will be born.
The research has enabled the team to develop genetic mapping techniques that help identify regions of the bovine genome containing genes that contribute to local adaptation. This paves the way for genetic tests of cattle that can look for the presence of specific adaptations, such as heat or altitude tolerance, and identify locally adapted individuals. This is particularly important in the light of changes in current environmental stressors due to climate warming.
“Efficiency and productivity have vastly improved in the last 60 years,” said Professor Decker, but environmental stressors are never going to go away. Farmers need to know more about the genetic makeup of their herd, not only for the short-term success of their farm, but for the success of future generations.”
“As a society, we must produce food more sustainably and be good environmental stewards,” said Professor Decker. “Making sure a cow’s genetics match their environment makes life better for cattle and helps farmers run efficient and productive operations. It’s a win-win.”