The productivity of sheep depends on a number of quantitative characteristics and, above all, on the live weight, clip, length, fineness, and density of wool. The article presents the nature of the heritability of these traits in meat breeds of Etti merino, Dohne, and Australian meat merino breeds imported to the foothills of the southeastern region of Kazakhstan. It has been established that the efficiency of breeding in experimental sheep depends on the degree of heritability of the bred trait, and that the improvement of productive traits of sheep largely depends on their heritability and variability. As a result of comparing the level of development of live weight, clip, density, length, and fineness of wool by the method of a single-factor variance complex, it was found that the genotypic diversity of economically useful traits in experimental animals is mainly objective. This is especially noticeable when determining the live weight and clip of wool from mother-sheep and daughter-sheep received from them at the same age. Moreover, the older the animals, the clearer this manifestation becomes. Approximately the same pattern is observed in both the density and length of the wool.