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How much genetic progress are dairy producers making?
Dairy Pipeline: December 2001
Bennet Cassell
Extension Dairy Scientist,
Genetics and Management
540/231-4762
email: bcassell@vt.edu
Virginia dairy farmers are getting a lot of milk out of cows these days. Production per cow for DHI herds has been at an all-time high for the past year. There are lots of reasons of course, not the least of which is more specialized dairy operations that manage nutritional programs very closely. Genetics plays a role as well. I did some checking on genetic trend for the past three years to see just how much genetic progress we are currently making for milk production. National average annual genetic trend in breeding value of cows (that's twice their PTA) has been 253 lbs./year for milk in Holsteins for the last three years. Genetic progress in Jerseys was 188 lbs./year for the same period, while Swiss progressed at 224 lbs./year, Guernseys at 177 lbs/year, and Ayrshires at 118 lbs./year. High producing cows work their bodies hard, and more than a few of them are showing the strain. Reproduction and general health are emerging as management problems, causing some breeders to question whether continued selection for higher production is worth the extra costs that come with it. I was curious to see if recent genetic trend for milk production had changed from what it was in the past. USDA figures showed that Holsteins improved at 155 lbs. per year (again in breeding values) in the three years' prior to 1973, about the time we started to make real genetic progress in dairy cattle breeding. That number increased to 195 lbs./year in 1978, 213 lbs./year in 1983, 218 lbs./year in 1988, and peaked at 261 lbs./year for the three years leading up to 1993. Current genetic progress is just below that at 253 lbs./year. Have we peaked in rate of genetic progress for milk yield? If so, the trends aren't so clear just yet. What is clear is that dairy farmers should select for traits that make them the most money. The bottom line should dictate breeding programs. Healthy cows that last are a worthy goal, but the best breeding goal on any farm is lifetime economic merit. Production will remain prominent in that picture, though perhaps less prominent, in the years to come.