ABSTRACT
The genetic picture of horses bred for cutting and reining is indeed interesting and is quite different from racing horses. When cutting- or reining-futurity horses are measured and studied, we are dealing with a very narrow segment of the total horse population or breed. Because of the selectiveness of the group being studied, most of the variation observed is because of environment, training, riders, etc., and the resulting estimate of heritability is low. In studying pedigrees, one should be cautious about going too far back in an attempt to introduce the blood of a certain horse into his breeding program. Linebreeding requires mating of animals that are more closely related than are the average of the breed. Inbreeding is the mating of closely related animals. Both linebreeding and inbreeding, when practiced with careful culling, have the effect of increasing the desirable genes for which the breeder is selecting.
