The fertilizing ability of stallion sperm after freezing is lower than in other species. The search for the optimal extender, combination of extenders, and the freezing protocol is relevant. The aim of this study was to compare lactose-chelate-citrate-yolk (LCCY) extender, usually used in Russia, and Steridyl^® (Minitube) for freezing sperm of stallions. Steridyl is a concentrated extender medium for freezing ruminant semen. It already contains sterilized egg yolk. Semen was collected from nine stallions, aged from 7 to 12 years old. The total and progressive motility of sperm frozen in Steridyl was significantly higher than in semen frozen in LCCY. The number of spermatozoa with normal morphology in samples frozen in LCCY was 60.4 ± 1.72%, and with Steridyl, 72.4 ± 2.10% (p < 0.01). Semen frozen in Steridyl showed good stimulation of respiration by 2.4-DNP, which indicates that oxidative phosphorylation was retained after freezing–thawing. No differences among the extenders were seen with the DNA integrity of spermatozoa. Six out of ten (60%) mares were pregnant after artificial insemination (AI) by LCCY frozen semen, and 9/12 (75%) by Steridyl frozen semen. No differences among extenders were seen in pregnancy rate. In conclusion, Steridyl was proven to be a good diluent for freezing stallion semen, even though it was developed for ruminants.

Interest in the use of assisted reproductive technology in reindeer husbandry has gradually increased during the last decades. This article reviews Western and Russian literature on reindeer semen collection, semen cryopreservation and artificial insemination. In addition, literature on the synchronisation of the stage of reindeer oestrous cycle among females, recovery of in vivo embryos, embryo transfer, the production of in vitro-produced embryos and pregnancy diagnosis is reviewed.

To assess sperm quality, it is important to evaluate energy metabolism. The test substance 2.4-dinitrophenol (2.4-DNP) is an agent for destroying oxidative phosphorylation. 2.4-DNP shuts off the production of adenosine triphosphate (ATP) from oxidation and then, the respiration rate increases. If the respiratory chain is damaged, there is little or no response to adding 2.4-DNP. The aim of this study was to analyze the respiratory activity and oxidative phosphorylation in semen before and after freezing and compare the obtained data with the fertilizing ability of sperm. There was a reduction in sperm respiration rates in all species after thawing. The respiration of spermatozoa of boars, bulls, stallions, reindeers and chicken showed responses to 2.4-dinitrophenol. The only difference is in the strength of the response to the test substance. After freezing and thawing, respiratory stimulation by 2.4-DNP decreased. The results of our study show that respiration rate is not correlated with pregnancy rates and egg fertility. However, there was a high correlation between the stimulation of respiration by 2.4-dinitrophenol and pregnancy rates. The test for an increase in respiration rate after adding 2.4-dinitrophenol could be a suitable test of the fertilizing ability of sperm.

The analysis of relevant and significant scientific research on the physiological and biochemical aspects of ketosis, and the main mechanisms of influence on reproductive function in this metabolic pathology is presented. Strengthening breeding potential and creating conditions for its implementation through modern feeding and maintenance technologies led to the spread of diseases of non-communicable etiology, including ketosis diseases. Ketotic diseases cause various disorders in carbohydrate-lipid, protein, water-electrolyte and vitamin-mineral metabolism. The monitoring of studies on the biological role of ketosis showed its effect on animal fertility, quality of female gametes and fetal development. When considering ketosis, it is important to understand precisely the mechanisms of influence, since many methods for diagnosing and combating ketosis diseases are based on their knowledge. The key mechanisms of ketone bodies formation, the reasons for increase in their concentration were considered. It is of great practical importance for development of diagnostic tests that make it possible to determine the direction of disturbances in energy and plastic processes. Based on the data presented in the studies, conclusions were drawn about the role of -hydroxybutyric acid as a direct factor in reducing the reproductive function of Bos taurus .

У клинически здоровых коров голштинской породы (n=25) изучена динамика гормонального обмена в первый триместр стельности коров. С этой целью у коров в сыворотке крови определяли концентрацию кисспептина, 17βэстрадиола, прогестерона и кортизола. За животными вели регулярное наблюдение с проведением клинических и акушерско-гинекологических исследований. Уровень кисспептина в первый триместр стельности возрастал практически на протяжении всего рассматриваемого периода с понижением концентрации до 194,23±23,61 пг/мл на 98 день. Уровень эстрадиола на протяжении первого триместра возрастал с 49,66±9,68 до 76,20±17,84 пг/мл, соответственно, что также объясняется включением в его синтез и секрецию фетоплацентарного комплекса. Концентрация прогестерона и кортизола была в среднем на одном уровне. В ходе эксперимента из 25 животных у 14-ти на 30-ый день после осеменения зафиксирована эмбриональная гибель. Вследствие этого было сформировано две группы: 1-ая группа – животные с нормальным течением беременности и 2-ая группа с эмбриональной гибелью. Анализируя данные иммуноферментного анализа у животных 1-й группы, можно отметить снижение уровня кисспептина на 11% на 28-ой день в сравнении с 14-м днем после осеменения. При этом концентрация эстрадиола напротив повысилась на 29%. Во-второй группе напротив уровень кисспептина и эстрадиола не изменился и в среднем остались практически на одном уровне. На 28-й день после осеменения в первой группе концентрация кортизола была достоверно выше по сравнению со второй группой – 15,32±3,23 и 9,00±0,89 нмоль/л, соответственно. Данные по кисспептину и эстрадиолу не показали достоверных различий. Однако интерес представляет то, что в первой группе при повышении уровня эстрадиола происходит понижение уровня кисспептина. В частности, это согласуется с ранее проведенными исследованиями, согласно которым подобное взаимовлияние данных гормонов, может регулироваться высокой концентрацией прогестерона.

The fundamental goal of animal husbandry is the cost-effective production of human food from healthy animals, which includes production, reproduction. The method of whole-genome association study (GWAS) is actively used in various fields, including agriculture. Genome-wide association analyzes were generated as an identifier for genomic variations associated with economically significant traits in different livestock species. This method of genomic selection provides new priorities for improving the productive and reproductive qualities of livestock.The purpose of this review article is a comprehensive analysis of the current state of GWAS in cattle, focusing on the identification of SNPs associated with reproduction, productivity, growth, behavior and genetically determined diseases. The scope of the article covers the study of GWAS results worldwide, both in dairy and beef cattle, with special emphasis on the identification of candidate genes, QTL and genome regions related to the direction of productivity. Additionally, the organization of this review will include a classification of GWAS results based on the specific traits studied, providing a comprehensive overview of the genetic determinants of reproduction, growth, behavior, and disease traits in cattle.