This work presents the material of research and production experiments on the crossing of stud rams of the North Caucasian meat and wool breed and Australian meat merino with fine wool ewes of a commercial herd. It is identified that the use of North Caucasian rams on fine wool ewes serves to increase the fertilizing ability and milk production of the breeding stock, to increase viability and resistance of young animals, as confirmed by the best morphometrical differences of crossbred offspring placentas. Crossbred offspring from semi-fine wool rams had a large live weight at birth at 21 days and at 4 months of age. The use of Australian producers did not have a significant effect on the above indicators of economically useful traits in comparison with purebred breeding.

Organizing and conducting scientific and farm experiment is one of the most important components of any scientific and research work. The features of the modern period of animal husbandry development, the state of the feed base in all categories of farms, the availability of qualified specialists, the level and culture of conducting selection and technological techniques, create the main conditions for reliable performance of experimental researches. In sheep breeding the success of research work on the selection plan depends to a large extent on careful individual accounting of the results of insemination and lambing of ewes. Currently, in different categories of sheep farms crossbreeding is used as one of the methods for faster improvement and increasing the productivity of animals. At the same time, it is not always clear from the materials of many researches how the experimental groups of breeding stock were formed, what rules of selection were observed during artificial insemination, how accounting was carried out during insemination and lambing of ewes, what justifies the calculation of some indicators of economic effectiveness of the research without taking into account important economically useful features. The recommendations on how to eliminate possible errors when conducting research and production experiments by young scientists have been provided in the article. In particular, the main principles of forming experimental groups of sheep by age, productivity and origin have been shown. The necessity of housing all sex and age groups of experimental animals with complete feeding has been noted. The most important condition is the same number of ewes inseminated every day with the semen of each mating stud ram. It has been recommended to use vasectomy teaser rams for the authenticity of the origin of the obtained off spring. Special attention has been paid to the need to take into account all valuable economic useful features studied in the course of scientific and production experiments to calculate some indicators of economic effectiveness when rearing off spring of different origin.

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