Rough hair coat has long been associated with Tall Fescue toxicosis, a condition in cattle consuming endophyte-infected tall fescue. This fungus produces toxins that decrease production and make rough hair coats in cattle that consume infected fescue. All cattle tend to get rougher hair coats in late winter, but by April to early May, cows should have shed their winter hair coats. Cattle that are well suited to their environment suffer less stress. One of the greatest environmental challenges for beef producers is heat stress. This is especially true where relatively high humidity levels intensify hot temperatures in which cattle must cope to remain comfortable and productive. Recent research has shown that hair shedding scores are an easy and effective way to measure cattle's ability to cope with heat stress.

Hair shedding scores are simply a visual appraisal of the extent of hair shedding and are reported on a 1 to 5 scale. A score of 5 indicates an animal that retains its complete winter coat and exhibits no evidence of shedding while a score of 1 is given when cattle have completely shed their winter hair coat and exhibit a slick summer hair coat. The amount of the winter coat shed by Mid-May is an effective predictor of a cow’s ability to cope with heat stress. Earlier shedding can be an indication of improved productivity and adaptation to the production environment. Regardless, calves from cows that shed their winter hair coat weigh more at weaning, with some estimates as large as 24 pounds. 

Early research has found that the heritability of hair shedding has been estimated to be approximately 0.35, meaning that 35% of the variation in hair shedding is due to genetic differences. Also, data suggest early shedding of the hair coat early may be controlled by only a few alleles and the possibility exists to find a genetic marker predicting the ability of cattle to tolerate tall fescue, the predominant forage in KY. Although a hair shedding genetic prediction (i.e, Hair Shedding Expected Progeny Difference) would be the preferred method to select for increased hair shedding, these predictions are not yet available. 

We have identified 25 farms (about 1000 cows) to evaluate the cattle's ability to shed hair coats and its implications on animal performance. Outliers (scores 1 and 5) will be blood sampled and these cows will enter our database. The blood samples will be evaluated by researchers at the USDA Meat Animal Research Center in Clay Center NE with the goal of developing a valid genetic prediction tool for fescue tolerance. Data will be collected in a two-three year study.