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Virginia Cooperative Extension - Knowledge for the CommonWealth

Are you losing money by making inbred matings?

Dairy Pipeline: January 2001

Bennet Cassell
Extension Dairy Scientist
Genetics and Management

Are you losing money by making inbred matings? Each 1% increase in inbreeding in a mating will cost about $24 in lifetime profit from the calf. A few minutes of planning can avoid most of those losses. Of nearly 600 Holstein bulls actively marketed in our area, over a third are sired by one of eight different bulls. Luke has 36 sons in those 600 bulls. Aerostar, and his half brother, Prelude account for 32 and 21 sons, respectively. Elton has 36 sons, Blackstar and Mandel each have 24 sons, Bellwood has 23 sons and Leadman has 20 sons in that group of 600 bulls. Most of these "sires of sons" are related among themselves through Elevation and Chief lines of breeding. What individual dairy farmers need to watch are matings that are closer than they realize. If you breed an Elton daughter back to one of those Elton sons, you have just made a half-sib mating that produces at least 12.5% inbreeding that costs about $300 in lifetime profit. Most breeders wouldn't miss that one very often, but some relationships are harder to pick up when a mating sire is chosen. For instance, Blackstar has had proven sons in AI for several years, and many cows in Virginia herds are sired by Blackstar sons. If you mate one of those cows to one of those 24 Blackstar sons still being marketed, the resulting inbreeding is at least 6.25%. The loss in lifetime profit is about $150 compared to a mating that produces no inbreeding. Another mating that generates 6.25% inbreeding occurs when the sire of the cow and the maternal grandsire of the bull are the same. Jersey breeders face even greater challenges from inbreeding, because the number of bulls available are more limited. Of almost 100 Jersey sires in the AI marketplace, 26 are sired by Berretta. Alf, Lester, and Sooner account for another 26 sons, so those four bulls are sires of over half the Jersey bulls currently available. It does pay to watch pedigrees when service sires are chosen. You cannot "un-inbreed" a calf after the mating is made.

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