If inbreeding is avoided, how much heterosis can be retained in a composite?
The more breeds in a composite, the more heterosis can be retained. Heterosis can range from 50 percent of the maximum possible heterosis for a two-breed composite to 75 percent for a four-breed composite. Retained heterosis can be estimated from the formula n – 1, in which n is the number of breeds in the composite. For example, n 4 – 1 4 = 75% for a four-breed composite. Levels of maximum heterosis for various mating systems are given in Table 1. Are there other considerations in forming a composite? Selection of the breeds that go into the composite is a critical step. Breed differences (complementarity) should be fully exploited so as to match the composite with the environment in which it will be used and to match it with market specifications (carcass size, percent retail product, marbling, etc.). In addition, special attention should be paid to lowly heritable traits and to traits that are difficult to measure (e.g., mammary system, sheath, skeletal soundness, etc.) to minimize