Background Sheep were among the first animals to be domesticated. They are raised all over the world and produce a major scale of animal-based protein for human consumption and play an important role in agricultural economy. Iran is one of the important locations for sheep genetic resources in the world. Here, we compared the Illumina Ovine SNP50 BeadChip data of three Iranian local breeds (Moghani, Afshari and Gezel), as a population that does not undergone artificial breeding programs as yet, and five other sheep breeds namely East Friesian white, East Friesian brown, Lacaune, DorsetHorn and Texel to detect genetic mechanisms underlying economical traits and daptation to harsh environments in sheep. Results To identify genomic regions that have been targeted by positive selection, we used fixation index (Fst) and nucleotide diversity (Pi) statistics. Further analysis indicated candidate genes involved in different important traits such as; wool production included crimp of wool (PTPN3, NBEA and KRTAP20–2 genes), fiber diameter (PIK3R4 gene), hair follicle development (LHX2 gene), the growth and development of fiber (COL17A1 gene)), adaptation to hot arid environments (CORIN gene), adaptive in deficit water status (CPQ gene), heat stress (PLCB4, FAM107B, NBEA, PIK3C2B and USP43 genes) in sheep. Conclusions We detected several candidate genes related to wool production traits and adaptation to hot arid environments in sheep that can be applicable for inbreeding goals. Our findings not only include the results of previous researches, but also identify a number of novel candidate genes related to studied traits. However, more works will be essential to acknowledge phenotype- genotype relationships of the identified genes in our study.

The results of the studies highlight the usefulness of application of the concept of the desired type for herd of Jersey breed. The researches have conducted in the herd of the Jersey breed of «Dan-Milk» subsidiary of Chernyakhiv district of Zhytomyr region. Zootechnical and breeding records have been established at a high level. The implementation of various zootechnical and technological operations greatly facilitate by the introduction of the automated information system "Uniform Agri". The conditions for raising, feeding, keeping and using cows ensure the realization of their genetic potential for milk production. Milking of cows held on the "Parallel". Keeping cows unattached to rest boxes. The rations have made according to the physiological state and the level of productivity of the animals. The correspondence of the indices of first-calf cows of cognate groups, offspring of booger-breeders, differentiated groups by the value of the animals of the desired type was determined by the mean normalized deviation (t) in fractions of the mean square deviation (σ) according to the concept of the desired type by the method of M. Pelekhaty and L. Piddubna. The cows were characterized by 6 indicators of dairy productivity and 5 – reproductive ability of the first lactation. Improving the economically useful traits of cows to parameters of the desired type were carried out by using various breeding techniques. The offspring of bulls Headline 114114336 (t = -0.27) and DJ Jante 302761 (t = -0.30) had the best fit for the parameters of animals of the desired type according to the studied characteristics, the worst was Karl 67037285 (t = -0.77). As a result of researches it has been established that indices of cows of different cognate groups have characterized by less conformity to parameters of animals of the desired type, in comparison with the results of daughters of individual sires on the average value of normalized deviation. Cows of the Fallneva’s 593883 (+0.01) cognate group are closer in terms of reproducibility to animals of the desired type of cows, Surville’s 604694 (-0.06) are the least, and in the milk productivity, the Observer’s 553236 (-0.56) related group and Fallneva’s 593883 (-0.82), respectively. With the increase in the milk yield of Jersey cows, there was a decrease in the difference between the indices of animals of different groups with corresponding parameters of animals of the desired type. With the increase in the level of milking from 10 thousand. slightly better cows (t = +0.06) have observed for the parameters of the animals of the desired type, but this result is due to the very low reproductive ability of the cows and long lactation, which makes it impossible to repair the herd in time for its own young. In 36 cases out of the 55 cows with different levels of dairy productivity were significantly inferior to parameters of the animals of the desired type, accounting for 65.5% of the total number of comparisons. It is advisable to select animals with a milk yield of at least 9000 kg of milk, which will lead to an increase in the number of cows of the desired type in the herd. The most usefulness methods of creating a high-performance dairy herd for «Dan-Milk» subsidiary have been identified and presented. They identified the use of Jersey sires cows and the selection of cows by milk yield (the average normalized deviation on reproduction ability were -0.07 and -0.08, on the basis of dairy productivity -0.73 and -0.72).

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The aim of the work was to study the influence of biological periods of reproduction of first-born cows of Simmental breed on their productive features of organic and conventional milk production. Research materials and methods. The research was carried out in the herds of Simmental breed PС "Halex-Agro" (organic milk production, n = 272) and LLC "Myroslavel-Agro" (conventional milk production, n = 120) Novograd-Volyn district of Zhytomyr region according to conventional methods. Research results. The article presents the results of research on the influence of the age of the first fertile insemination, age of first calving, the duration of service and dry periods of Simmental cows in their productive traits in organic and conventional milk production. The best indicators, regardless of the technology of milk production, were characterized by animals of the middle group, the age of the first fertile insemination of these animals in PE "Galex-Agro" ranged from 526 to 678 days, and in STOV "Miroslavel-Agro" – from 505 to 648 days. The value of this indicator within farms was 462.5 and 458.0 kg, respectively. Therefore, both early insemination and late insemination were not desirable for this herd, because with early insemination farmers don’t get enough milk and there is a high probability of giving birth to calves with lower live weight, while with late insemination there is an irrational overuse of investments in uncovered heifers. their future milk productivity. In the conditions of both farms there is a clear pattern that animals with an earlier age of the first fertile insemination are characterized by more intensive formation of live weight. Animals of the first and second experimental groups were statistically significantly superior to peers of the third experimental group in live weight at the age of 3 to 18 months in PE "Galex-Agro", and from 6 to 18 months in STOV "Myroslavel-Agro" (P < 0.05–0.01). There is almost the same live weight of heifers at different ages in both farms, due to the common origin of the breeding stock imported from the Czech Republic. It has been established that with increasing age of the first calving milk productivity of cows increases. The highest yield for 305 days (6117.2 and 5937.6 kg) and all lactation (6920.9 and 6953.4 kg) were observed in cows whose age of first calving was 995 and older and 917 and older days in the conditions of PE "Galeks-Agro” and STOV “Myroslavel-Agro” respectively. The lowest yield for 305 days (5733.9 and 5863.0 kg) and all lactation (6528.2 and 6424.6 kg) were in cows with the age of the first calving 835 and less and 778 and less days in both farms, respectively. There was a statistically significant effect (P < 0.01–0.001) of the duration of the service period in both farms on the duration of lactation of cows (58.6 and 63.9%), hopes (22.8 and 34.2%), as well as on the fat content in milk (2.2%) only in the conditions of PE "Galex-Agro". In the conditions of intensive management of the dairy industry in organic and conventional production, it is necessary to take into account the rate of reproduction of the herd, which is largely determined by the length of the service period. The service period is one of the key indicators that determines not only the reproduction of animals, but also their future milk productivity. Conclusions. According to the results of our own research, it was found that the extension of the service period leads to an increase in the duration of biological periods of reproduction and to a decrease in the coefficient of reproducibility (from 1.06 to 0.68; from 1.05 to 0.72), which is predictable. Statistically significant effect (P < 0.001) of the value of the service period was found in the conditions of PE "Galex-Agro" and LLC "Miroslavel-Agro" on the duration of the interbody period (74.2 and 68.8%), the coefficient of reproducibility and 78.2), as well as the duration of the dry period (2.6%) and the age of the first calving (2.7%) only in the conditions of PE "Galex-Agro". When comparing animals with a shortened and optimal duration of the dry period, a statistically significant difference was found in the conditions of organic production in the duration of lactation (25.3 days), milk yield during lactation (673 kg) and 305 days (359 kg), milk fat (13.7), milk protein (13.4 kg), total milk fat and protein production (26.2 kg). In terms of conventional production, animals with a shorter dry period are characterized by longer lactation and higher milk yield.

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