Polymorphism of the genes associated with the formation of productive traits of animals is studied in order to increase the breeding efficiency. The article presents the results of DNA genotyping and live weight indices of replacements of the Dagestan mountain sheep in the age dynamics. The animals carrying the desirable breeding-relevant allele GHB and having heterozygous genotype GHAB surpassed their peers carrying homozygous genotype GHAA in live weight by 2.9 % at the age of 2 months, by 3.5 % at the age of 4 months, and by 5.4 % at the age of 8 months. The index of live weight of the animals carrying the desirable breeding-relevant allele GDF9A with heterozygous genotype GDF9AG and homozygous genotype GDF9AA was several times higher than the one of their peers carrying homozygous genotype GDF9GG; they differed by 5.0 and 10.1% at the age of 2 months, by 2.0 and 5.7% at the age of 4 months, and by 2.4 and 6.1% at the age of 8 months, respectively. The study revealed complex genotypes with the allelic profile represented by one (GHAAGDF9AG), two (GHAAGDF9AA), and three (GHABGDF9AA) selection-relevant marker alleles. It was noted that greater values of live weight were in the animals carrying complex genotypes GHAAGDF9AA, GHAAGDF9AG and GHABGDF9AA, amounting to 14.8, 14.5, 15.3 kg at the age of 2 months, 26.4, 26.2 and 26.9 kg at the age of 4 months, and 33.6, 33.8 and 34.9 kg at the age of 8 months, respectively, against the peers carrying complex genotype GHAAGDF9GG, amounting to 14.3, 25.8 and 32.8 kg, respectively.

The article presents the results of DNA genotyping of sheep of different breeds. It is the first time polymorphism of genes GH-HaeIII and CAST-MspI of replacement sheep of different breeds has been studied and analyzed. The testing results identified specific features of the allele spectrum of the studied genes associated with meat production, expressed in different frequencies of occurrence of both genotypes and alleles. Carrier animals with desirable alleles for breeding were identified in the gene loci under study. Genetic and statistical analysis allows to conclude that the specific weight in the studied populations of sheep of different breeds of particularly valuable genotypes is relatively low. In order to accumulate selection-significant genetic markers in the breeding herds of sheep of different breeds, bred under conditions of the Stavropol Krai and the Republic of Dagestan, regular screening will create conditions for identifying desirable alleles and genotypes, as well as their wide inclusion in the breeding process.

Мелихова Надежда Павловна, канд. с.-х. наук, старший научный сотрудник отдела орошаемого земледелия и агроэкологии, Всероссийский научноисследовательский институт орошаемого земледелия. Россия. Зибаров Анатолий Александрович, канд. с.-х. наук, зав. отделом орошаемого земледелия и агроэкологии, Всероссийский научно-исследовательский институт орошаемого земледелия. Россия.

Here is presented the analysis of sheep meat productivity of the Russian meat Merino breed  and the effectiveness of selection for large size of animals, the severity of meat forms, and their higher precocity is shown. The selection differential for live weight in animals of different gender and age groups was determined, which is 5.0-26.0 kg, or 10.0-32.5%. The number of Russian meat Merino sheep (n=1045) is characterized by the severity of meat forms (T5) and has a desirable type of physique, exterior and meat productivity (100%), which confirms the consolidation of the herd on this basis. It was found that the genetic resources of the herd allow young sheep to receive a high average daily increase in live weight (170.4 g) from birth to 4.5 months. It is experimentally proved that the offspring of the PMM breed with intensive feeding is characterized by a higher growth energy. It is noted that the descendants of meat Merino have a large carcass mass of 12.4%, a slaughter yield of 2.2 abs. percent and a meat content coefficient of 21.3%, compared to the Stavropol sheep breed of wool productivity. Experimental data confirm that the sheep’s meat of the Russian meat Merino breed is " marbled, has high quality and consumer properties.

An analysis of the wool productivity in Caucasian breed sheep of various sex and age groups is presented, and the effectiveness of selection in terms of the length, fineness, thickness and yolk of wool is shown. It was revealed that in the CJSC of “Plemzavod named after V.V. Kalyagin, the Hero of Socialist Labor”, the average clip of greasy wool is 5.8 kg when the yield of washed fiber is 59.1%. It has been established that the genetic recourses of the herd enable the farm to receive an average clip of 3.4 kg of washed wool. The selection differential for washed wool clip in animals of different sex and age groups was determined, which has made 0.9-3.3 kg, or 28.8-63.5%. The sheep capita of the Caucasian breed in the breeding plant is characterized by very thick wool (95.7%), which is confirmed by experimental data, where the total thickness of the hair follicles is 59.1 pieces per 1 mm2 of skin. It was established that the selection differential by the length of wool in the context of sex and age groups varies within 1.5-3.5 cm, or 16.7-43.8%. The revealed differentiation of wool fineness in Caucasian breed sheep confirms the consolidation of the herd by this trait, where the 64th quality is the leading fineness. It was experimentally established that the amount of wool fat in greasy non-fatted wool is 8.3%, the amount of wool sweat has made 12.1%, and the amount of diphilic substances is 3.2%. The ratio of wool fat: wool sweat is 0.70. It is noted that animals of the Caucasian breed have a white wool yolk (94.9%) and a sufficient amount of it (95.6%), which indicates a good consolidation of this trait in the sheep capita.