The aim of this study was to create balanced media for the cryopreservation of rooster semen in pellets to maintain the functional state of the sperm after thawing. Fructose was replaced by trehalose in experimental media in proportions of 10% (LCM-T10) and 20% (LCM-T20), while LCM was used as a control. After artificial insemination of the hens, the eggs were incubated (n = 400). To determine the functional safety of spermatozoa in the genital tract of hens after 5, 10, and 15 days from the last insemination, we used a method for assessing the interaction of sperm with the perivitelline membrane. Significantly higher rates of egg fertilization (82–86%) were obtained when using LCM-T10 and LCM-T20 compared to control (79%, p < 0.05). Egg fertility on the 5th day from the last insemination with the LCM-T20 diluent reached 100% versus 86% in the control; on the 10th day, the fertility rates were 55% versus 20%, respectively. The best results for fertility duration were obtained by freezing spermatozoa with LCM-T20 medium. The numbers of interaction points of spermatozoa with the perivitelline membrane were as follows: on the 5th day from the last insemination with LCM-T20—461.5 ± 11.5 holes/cm2 (LCM-control—13.7 ± 2.7 holes/cm2), p < 0.01; on the 10th day with LCM-T20—319.3 ± 12.9 holes/cm2 (LCM-control—14.9 ± 3.5 holes/cm2); and on the 15th day with LCM-T20—345.2 ± 11.1 holes/cm2 (LCM-control—0 holes/cm2). In conclusion, the use of trehalose in LCM diluent medium can increase the fertility of frozen/thawed sperm and the duration of their fertility in the genital tract of hens.

Summary Local breeds can serve as an important source of genetic variability in domestic animal species. This study aimed to assess the genetic diversity and population structure of Belarusian Red cattle and their differentiation from other European cattle populations based on genome‐wide SNP genotypes. Twenty pedigree‐recorded non‐closely related cows of Belarusian Red cattle were genotyped using the Illumina BovineHD BeadChip. Genotypes of 22 other European cattle breeds were included in the study for comparison. A total of 28 562 SNPs passed through the quality control checks and were selected for analysis. The Belarusian Red cattle displayed a moderate level of genetic variability (UHE = 0.341, HO = 0.368), and the highest heterozygote excess (UFIS = −0.066), among the studied breeds; this reflects the contribution of multiple breeds to their formation. The principal component analysis, FST‐based Neighbor‐Net tree and Admixture clustering, clearly distinguished the Belarusian Red cattle from the other European cattle breeds. Moreover, the presence of ancestral genomic components of Danish Red and Brown Swiss breeds were clearly visible, which agrees with the breed's history and its recent development. Our study highlights the importance of maintaining the specific genomic components, which makes a significant contribution to the global genetic diversity in the modern population of Belarusian Red cattle, allowing us to consider them a valuable national genetic resource. Our research results will be useful for the development of conservation programs for this local cattle breed.

Currently, there is virtually no information on genetic factors affecting the yield of allanto-amniotic fluid, which is the raw material for the production of human and animal vaccines. Association studies including this trait are beneficial for increasing productivity of a biotechnological line of chickens used for the production of 'Clean Eggs'. We examined here a population of the Russian White breed for the effects of indels in the prolactin (PRL) and dopamine receptor D2 (DRD2) genes on the yield of extraembryonic fluid (YEF) and embryo weight at 12.5 days of development. A 24-bp insertion in the 5' flanking region of the PRL gene significantly (P<0.01) increases YEF in the embryos. The heterozygous embryos contained the highest YEF (9.6 mL) than that of the homozygous insertion (9.4 mL) and deletion embryos (8.4 mL). We also found a significant association (P<0.001) between the PRL genotypes and egg weight (EW). The results of the present study suggest a significant association between the PRL gene variation and quantitative traits in the Russian White chickens, contributing to a long-term programme on the effective use of the genetic potential of Russian gene pool breeds and populations of chickens.

The combination of saccharides in the composition of a cryopreservation medium may represent a promising method for the preservation of the reproductive cells of male birds. In the current study, cryoprotective media with a combined composition of mono- and di-saccharides were developed. The degree of penetration of reducing saccharide molecules (maltose—Mal20 medium) and non-reducing disaccharide molecules (trehalose—Treh20 medium) from the cryoprotective medium into the cytosol of rooster spermatozoa was studied. LCM control media without disaccharides were used as the control. The number of maltose molecules penetrating from the outside into the cytosol of the spermatozoon was 1.06 × 104, and the number of trehalose molecules was 3.98 × 104. Using a combination of maltose and fructose, the progressive motility of frozen/thawed semen and the fertility rates of eggs were significantly higher ((p < 0.05) 40.2% and 68.5%, respectively) than when using a combination of trehalose and fructose in a cryoprotective diluent (33.4% and 62.4%, respectively). A higher rate of chromatin integrity at the level of 92.4% was obtained when using Treh20 versus 74.5% Mal20 (p < 0.05). Maltose positively affected the preservation of frozen/thawed sperm in the genital tract of hens. On the seventh day from the last insemination when using Mal20, the fertilization of eggs was 42.6% and only 27.3% when using Treh20. Despite the same molecular weight, maltose and trehalose have different physicochemical and biological properties that determine their function and effectiveness as components of cryoprotective media.

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