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Virginia Cooperative Extension - Knowledge for the CommonWealth

Key factors for genetic improvement

Dairy Pipeline: February 2002

Bennet Cassell
Extension Dairy Scientist,
Genetics and Management

Most dairy producers in Virginia do not remember the time when we had no bull proofs, only 3 or 4 AI bulls per breed using fresh semen, in other words, the good old days. We have come a ways - perhaps all the way to complacency about genetic improvement. The dairy cow you milk today is the present end product (she is still improving) of many years of careful selection and progeny testing by producers across the country and, increasingly, internationally. Even if you don't use AI, genes from bulls in AI are almost certainly in the bulls you buy from neighbors. There are two key factors behind all this genetic progress. The first is the accurate identification of cows, their ancestors, and their descendants. The second is accurate records of performance for traits we want to change through selection. Without these two key factors, the dairy cow you milk would be a different animal, and a less efficient one at that. Today's dairy managers have plenty on their plates and may not recognize the value of these two factors to their most important single resource, the cow herself. We could improve cow identification in this state. About 79% of cows in supervised DHI programs have sire identity recorded. Only 37% of cows in unsupervised DHI plans have sire ID. While on the subject of DHI, only about two thirds of cows in Virginia are on DHI milk recording systems. DHI is a herd management tool with important genetic benefits. Genetic evaluations for milk, fat, protein, productive life, and somatic cell score all come from DHI records. In the next few years, a national system for genetic evaluation of reproductive performance based on DHI records will be developed. These genetic evaluations help all dairy producers, directly or indirectly, through AI or through natural service use of sons of AI bulls. But it all goes back to some producers being willing to record parentage, progeny, and performance information. If you're one of the record keepers, thanks, and please keep it up. If you are not, well, how long has it been since somebody asked you to test and identify your dairy cows? I just did.

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