Identification of interspecific hybrids argali (Ovis ammon) and domestic sheep (Ovis aries) of different generations by exterior indicators

When creating new breeds and breeding forms, various breeding methods are used, including hybridization. For a long time in the Ernst Federal Science Center for Animal Husbandry, work is underway to use the genetic resources of wild species, in particular argali ( Ovis ammon ), to obtain interspecific hybrids with domestic sheep ( Ovis aries ) in the framework of creating new breeding forms and studying the biological characteristics of certain species of the genus Ovis . This raises the question of identifying the obtained interspecific hybrids. Along with conducting expensive studies on the genotyping of such animals, it is of interest to use informative phenotypic indicators characteristic of hybrid individuals. In this work, for the first time, comparative results of differentiation by exterior characteristics of interspecific hybrids of different generations from mating argali with sheep are presented. Romanov breed and original parental forms. The possibility of using exterior indicators for preliminary identification of hybrid individuals without expensive genomic studies was confirmed. Hybridization in the second and subsequent generations resulted in the splitting of hybrid individuals by genotype and phenotype. The work aimed at comparing morphometric parameters of the purebred Romanov sheep and their interspecific hybrids with argali and to reveal informative exterior indicators for identifying hybrid individuals. The lambs of Romanov breed ( n = 20) and the interspecific hybrids 1/2 Romanov sheep 1/2 argali (F1, n = 12), 3/8 Romanov sheep 5/8 argali (F3, n = 17), and 7/16 Romanov sheep 9/16 argali (F4, n = 18) were reared from birth under the conditions of vivarium (the Ernst Federal Science Center for Animal Husbandry, 2019-2020). The following measurements were recorded: height in withers, height at the sacrum, back height, oblique body length, body length, chest width, sacrum width, chest depth, metacarpal girth. Linear measurements were taken at the age of 6, 42 days, and 3 months using a measuring tape, tape measure, and a measuring compass. The animals were weighed on an electronic balance. To assess the development of animals on the basis of weight and linear measurements, the body indices were calculated: long-legged index, elongation index, overgrowth index, breast index, bone index, body mass index. The SPSS v.23 software was used for statistical analysis. As a factor influencing the linear measurements of lambs, the breed of individuals was chosen. Hybrid animals at the age of 3 months in comparison with purebred individuals of the Romanov breed had higher indicators of the long-legged index, which is typical for argali. The advantage of F1, F3 and F4 hybrids over purebred animals for this indicator was 4, 8 and 2 %, respectively. At the same time, hybrids F1, F3, and F4 had a more compressed rectangular body shape, therefore, they were inferior to purebred lambs in terms of elongation index, respectively, by 18, 22 and 18 % (p 1, F3 and F4 hybrids was 18, 20 and 14 % in oblique body length, 35, 33 and 20 % (p 1/2 and 5/8 argali bloodlines were grouped in one cluster. Hybrids with 9/16 bloodiness according to the argali and purebred Romanov sheep formed separate clusters. The results obtained confirm that the exterior pa