Study of growth and development indicators of purebred and hybrid sheep

Hybridization is important for establishing patterns of inheritance of phenotypic and genetic characteristics, for clarifying the existing zoological classification of animals and phylogenetic origin. It is also considered from the perspective of breeding new breeds of farm animals, characterized by high adaptive qualities, resistance to diseases, good productivity, and less demands on the quality of feed. It has been noted that in first-generation crossbreeds the effect of heterosis is observed; such animals often surpass the parental forms in terms of growth and development, and also have a higher growth rate. The aim of our research was to compare the growth and development indicators of purebred sheep and hybrid individuals obtained using argali sperm. The experiment was carried out on lambs of the Tajik meat-greasy-wool, Gissar breeds, as well as hybrids - the Tajik meat-greasy-wool breed with a hybrid of the Romanov sheep and argali and the Gissar breed with a hybrid of the Romanov sheep and argali. A comparison of the TMSSH and TMSSH x (R x A) groups showed differences in terms of live weight, so purebred sheep were inferior to hybrids by 1.06 kg (P≤0.001), in chest depth by 1.3 cm (P≤0.05), and in pastern girth by 0.69 cm (P≤0.001). Purebred individuals of the Tajik meat-grease-wool breed were inferior to hybrids G x (R x A) in terms of live weight by 1.06 kg (P≤0.05), in height at the withers by 1.73 cm (P≤0.001) and in chest depth by 1.54 cm (P≤0.05). The results of the studies showed that hybrid animals exceed purebred animals in live weight, chest depth, chest width and pastern girth.