The purpose of research was to study the association of polymorphic variants of growth hormone gene with development, slaughter traits and carcass composition in crossbred Red Angus × Kalmyk bull-calves. The experiment was carried out at LLC “Agrofirma Aduchi” in Republic of Kalmykia. The object of the study was crossbred Red Angus × Kalmyk (F2) bull-calves. The use of Red Angus sires with a high concentration of G allele in GH gene in the reproduction system of a herd made it possible to obtain second-generation crossbred progeny with a genotype distribution of 0.0625: 0.5: 0.4375, respectively, VV: LV: LL. The frequency of V allele reached 0.3125. The superiority of heterozygous individuals in live weight reached 18.0 kg by the age of 18 months (P>0.05). The maximum carcass weight was established in the group of heterozygous individuals, their superiority was 25.3 kg (P <0.01). The advantage in carcass yield of carriers of the minor allele V was 1.7% (P<0.05). The heterozygous animals were superior in flesh part weight in half-carcass by 11.1 kg (P <0.001). A less pronounced intergroup difference was found in bone weight, which reached 1.2 kg (P> 0.05). The monitoring the genetic structure of the herd taken into account the allelic distribution in growth hormone gene will provide the development of meat productivity potential.
В статье изложе ны результаты сравнительной оценки кожно-волосяного покрова бычков породы обрак французской селекции и сверстников-симменталов отечественной популяции при их выращивании до 19,5-месячного возраста в условиях Центрального Черноземья. Существенных различий между животными обеих пород по структуре волосяного покрова, диаметру волос, их массе, длине и густоте, а также по массе, выходу и толщине шкур в возрасте 15,5 и 19,5 мес. не выявлено. Эти материалы, наряду с другими, являются подтверждением успешно протекающей акклиматизации животных породы обрак в зоне Центрального Черноземья.
The climatic conditions of the sharply continental climate of the Stavropol Territory influenced the skin of gobies of the Kalmyk, Kazakh white-headed and Hereford breeds. During the year, the skin of animals changed, which contributed to the adaptation of the body to the climatic conditions of the dry zone. These conditions influenced the histology and morphology of the skin of 18-month-old gobies of Kalmyk, Kazakh white-headed and Hereford cattle breeds (6 animals of each breed). The results of the study showed that the greatest thickness of the skin has the Kazakh white-headed bullocks (6544±153 microns). The smallest thickness of skin was in animals of the Hereford breed (5602±140 microns). Kalmyk and Kazakh white-headed bulls had a higher content of fine (downy) hair than Hereford bulls did. The content of sebaceous glands in Kalmyk bulls was 1.5 times higher than that in Hereford bulls and 1.1 times higher than that in the Kazakh white-headed breed. The number of sweat glands in the Hereford breed was 1.4 times higher than that in animals of the Kalmyk breed and 1.3 times higher than that in the Kazakh white-headed. The highest content of type I collagen is detected in the skin of animals of Kalmyk and Kazakh white-headed breeds. The presence of a greater thickness of the dermis in combination with an increased content of sebaceous glands in the skin indicates a higher adaptive capacity of animals of the Kazakh white-headed and Kalmyk breeds of cattle to live in extreme weather conditions and affects the quality of raw materials.
Using a complex of morphological methods, the muscle tissue of 18-month-old gobies of three cattle breeds (Hereford, Kazakh white-headed and Kalmyk) was studied. The results of the study showed that in the biceps femoris muscle and the longest muscle of the back of bulls of Hereford breed, the average diameter of muscle fibers was higher than in animals of the Kazakh white-headed and Kalmyk breeds. The thickness of the endomysium in the muscles of the animals studied was in the range of 6–13 μm and had no pronounced breed differences. Among the cellular elements of endomysium, endotheliocytes prevailed. Their share was about 80%. Type 1 collagen was higher in Hereford animals. In the muscles of animals of the Kazakh white-headed and Kalmyk breeds, the content of adipose tissue was higher than in animals of the Hereford breed. The results obtained reflect typical patterns of the structural and functional characteristics of cattle muscle tissue, and also show the range of in-breed variability of the muscle tissue of these animals.
Based on the existing experience on combining the heredity of the Kalmyk cattle during breed development, we have developed a program to create a new type of beef cattle based on a combination of genotypes of Red Angus of American selection and Kalmyk breed in the Republic of Kalmykia in a dry steppe climatic zone. The purpose of work was to identify the potential weight growth in purebred Kalmyk heifers and daughters of the Red Angus sires of American breeding. For the study, 3 groups of heifers with 20 heads each were formed: Group I-purebred, II-crossbreed of the 1st generation: Red Angus×Kalmyk, III group-crossbred of the 2nd generation. Control rearing continued from birth to 18 months of age in the Republic of Kalmykia. Daughters of fathers of imported origin were relatively large-fruited. In the rearing period, intergroup differences in live weight were insignificant. At pre-weaning period until the end of the control rearing, the distance in weight growth between heifers of different genotypes increased. At 18 months of age, the difference reached 21.9-34.1 kg, the progeny of the 2nd generation had the maximum value. Half-blood daughters at all stages of live weight control were characterized by intermediate expression of the trait. The combined chick genotypes differed in long-growth, demonstrating a high growth rate up to 15 months of age. Influence of fathers on live weight variability of progeny increased with age, reaching a level of 26.65 % Лв 18 ЦШЧЭСs (P≤0.001).
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