In vitro fertilization (IVF) technologies have great potential in the preservation of endangered species. In the current study, an IVF experiment was carried out to evaluate whether reproductive technologies are suitable for Kazakh Whiteheaded cattle, aimed at preserving this breed whose population has reduced drastically over the last thirty years. The reproduction characteristics of Kazakh Whiteheaded cows were compared to Aberdeen Angus cows. Transvaginal ultrasound-guided ovum pick up sessions were carried out followed by in vitro embryo production and embryo transfer and pregnancy diagnosis. The total and viable oocytes per OPU procedure were 12.8 ± 1.18 and 8.7 ± 0.85 for the Aberdeen Angus breed, and 8.8 ± 1.04 and 6.2 ± 0.83 for the Kazakh Whiteheaded breed. Similarly, the mean number of cleaved oocytes and morula/blastocyst stage embryos produced by OPU/IVF were 4.8 ± 0.49 and 1.4 ± 0.15 for the Aberdeen Angus breed, and 2.4 ± 0.46 and 0.18 ± 0.05 for the Kazakh Whiteheaded breed (p ≤ 0.02). From fifty Kazakh Whiteheaded donor animals, 2585 oocytes were aspirated following six ovum pick up sessions. One thousand eight hundred and seventy-six (72.5%) oocytes were chosen for maturation and were further fertilized. The number of embryos cleaved was 720 (38.3% out of oocytes fertilized) on day four post-fertilization. Of these cleaved embryos, 56 (7.5%) developed into the late morula/blastocyst stage on day seven post-fertilization, averaging 1.12 embryos per donor animal. Pregnancy was detected in 12 recipients; 4 healthy calves have been born to date. The outcomes of our study have demonstrated that reproductive technologies can be applicable in preserving the endangered Kazakh Whiteheaded cattle. The findings in this report will enhance knowledge of the reproductive characteristics of endangered domestic animals and help develop sophisticated reproductive protocols for animals with unique reproductive mechanisms.

The article presents the results of research aimed at improving sheep productivity in the Republic of Kazakhstan through the effective use of genetic resources and reproductive crossbreeding. The objective of the study was to examine the live weight, exterior, and phenotypic characteristics of newborn lambs obtained from various breeding combinations in the farms “KH Bepen” (Abai region) and “LLP KH Aq Bas-Pavlodar” (Pavlodar region). A comparison was made between purebred and crossbred groups of animals in terms of live weight, wool yield, fertility rate, total lamb crop, and morphological parameters of newborns. The results of the research showed that the use of reproductive crossbreeding contributes to an increase in live weight and improvement of exterior traits in the offspring. Under the conditions of “Bepen,” crossbred lambs (KMW×KFTCW) demonstrated an increase in birth weight by 0.85–0.59 kg compared to purebred counterparts, as well as a more harmonious body conformation. In the “LLP Ak Bas-Pavlodar” farm, the differences were less pronounced, indicating that the manifestation of heterosis depends on the combination of breeds and management conditions. It was established that the offspring from interbreed crossbreeding exhibited greater diversity in coat color and tail shape, reflecting the genetic influence of paternal lines. An analysis of body conformation indices revealed an advantage of crossbred lambs in terms of body length and chest indices, indicating better trunk and chest development. The obtained results confirm the effectiveness of reproductive crossbreeding as a means of enhancing meat and wool productivity in sheep and improving the exterior characteristics of young stock. The conducted research has practical significance for the further improvement of breeding and selection programs, optimization of breed composition, and the development of strategies to increase the economic efficiency of sheep farming in Kazakhstan.

В данной статье представлены результаты научного исследования, посвящённого анализу роста и развития ягнят, полученных как от чистопородного разведения, так и в результате различных вариантов межпородного скрещивания. Проведённые наблюдения показали, что новорождённые ягнята всех исследуемых групп отличались высокой жизнеспособностью и хорошим физическим развитием, что подтверждается их достаточной живой массой при рождении. Особое внимание в работе уделено сравнению показателей живой массы чистопородных и помесных ягнят. Установлено, что у помесных ягнят данный показатель был значительно выше, чем у их чистопородных аналогов, что является свидетельством проявления эффекта гетерозиса. Гетерозис проявился, прежде всего, в ускоренном темпе роста, улучшенном развитии и повышенной жизнеспособности помесных животных. Также исследованы и проанализированы морфологические особенности телосложения ягнят. Полученные данные показали, что помесные ягнята отличались более приземистой и компактной конституцией тела, хорошо развитой грудной клеткой и облегчённым костяком. Такие характеристики приближают их по типу телосложения к животным мясного направления продуктивности. В первом поколении от мясошерстной породы помесные ягнята унаследовали ряд типичных признаков, что может свидетельствовать о целесообразности использования межпородного скрещивания с целью улучшения мясных качеств молодняка. Полученные результаты могут быть полезны для дальнейшего совершенствования методов разведения и селекционной работы в овцеводстве.

Sheep are the most widespread farm animal species on the globe due to many valuable biological and constitutional features, especially their high adaptive capacity. They are more technologically advanced animals, suitable for any industry system, namely, from purely stabling to year-round pasture keeping. One of the main directions of sheep breeding in Kazakhstan is meat sale, which gives a significant amount of the cheapest mutton and coarse wool necessary for the industry. Curd sheep by number of livestock occupy one of the first places in the country. The main mass of them is spread in semi-desert, desert, and dry-steppe zones of Abay and Pavlodar regions. The relevance of our study is due to the high importance of sheep breeding in the agrarian sector of the Republic of Kazakhstan. This industry provides production of meat, wool, leather and other demanded products, which have a stable demand both in domestic and foreign markets. However, for the sustainable development of sheep breeding, it is necessary not only to preserve the existing gene pool but also to ensure its rational use and improvement. Changes in climatic conditions, growing requirements for product quality, and high competition in the market require the application of modern approaches in breeding and stock management. The research aims to develop and apply modern breeding-technological and molecular-genetic methods to improve the genetic resources of sheep of different productivity directions. The results of the research were used to develop plans of selection and breeding work, which include the formation of new highly productive genotypes of sheep of different directions of productivity using the potential of domestic and foreign gene pools for the approbation of new breeding achievements. Thus, the conducted work confirms the efficiency of the developed selection-technological approaches.

The article presents a comprehensive analysis of the growth and development of bulls of the Kazakh white-headed breed of different body types (tall, moderate and compact) in the conditions of the peasant farm "Kairat" of the Pavlodar region. The main attention is paid to the study of the dynamics of live weight, measurements and body indices in different age periods (from birth to 18 months), as well as the relationship between body type and productive indicators. The study included regular weighing, body measurements, and body index calculations using variation statistics and correlation analysis methods. The results show that the tall body type shows the highest rates of weight gain and linear growth, which makes it promising for breeding work aimed at increasing meat productivity. The compact type is distinguished by more pronounced meat forms, latitudinal measurements and economy of feed use, which makes it preferable for breeding in conditions of limited resources. The moderate type, due to its balanced characteristics, can be considered as universal for meat production in various climatic conditions. The article emphasizes the importance of choosing a body type in the context of optimizing production processes and increasing the efficiency of the use of forage lands. The data obtained are of practical importance for improving breeding work, developing resource-saving technologies for growing young animals and adapting production to the conditions of the continental climate of the Republic of Kazakhstan.