We investigated the feasibility of cryopreservation of zebrafish (Danio rerio) blastomeres and primordial germ cells (PGCs) by rapid freezing of dechorionated whole embryos at the blastula, gastrula and segmentation stages. Initially we examined the glass-forming properties and embryo toxicities of 5 cryoprotectants: methanol (MeOH), ethylene glycol (EG), dimethyl sulfoxide (DMSO), propylene glycol (PG), and 1,3-butylene glycol (1,3-BG). Embryos at the blastula and gastrula stages had high sensitivities to cryoprotectant toxicities and were fragile against mechanical damage. Thus the segmentation stage embryos, the PGCs of which were visualized by injecting green fluorescence protein-nos1 3'UTR mRNA, were frozen using solutions containing each cryoprotectant at 6 M (first trial) and 2 types of cryoprotectants at 3 M each (second trial). In the first trial, live PGCs were recovered from most of the embryos frozen with EG (about 2 cells/embryo); however, a few embryos had live PGCs when embryos were frozen with other cryoprotectants. In the second trial; a mixture of EG + PG better preserved the viability of PGCs in frozen embryos. Live PGCs were recovered from all embryos frozen with EG + PG (about 3 cells/embryo), and the survival rate of PGCs was estimated to be about 25% based on the number of live PGCs in fresh embryos (about 12 cells/embryo). The present study indicates that we can utilize rapid freezing of dechorionated whole embryos at the segmentation stage for the cryopreservation of PGCs.

Results of estimation of metabolic processes state in pregnant sows at different stages of sow pregnancy realized in the conditions of the Republic of Belarus were presented. Research results showed that there were changes in the analyzed indexes (total protein; albumins; total lipids; triglycerids; lactate; urea; creatinine; glucose; cholesterin; bilirubin; ALP; AAT; SGPT; amylase; gamma GTP; calcium; phosphorous; magnesium; iron) of biochemical blood profile at different stages of sow pregnancy. The most expressed divergences of the analyzed indexes were stated at pregnant sows on the 90-th day of pregnancy (10 out of 19 indexes) which were caused first of all by feeding uncertainty. It was established that level of total lipids was low during all analyzed pregnancy days, notably that the lowest indexes were registered on the 60-th day period (2,81+/-19 g/l). The lowest level of triglyceride (0,12+/-0,04 mmol/l) was stated at the same period ,too. At a later stage, this index was within the limits of physiologic standard. High level of urea in blood was registered on the 80-th day of pregnancy. Low indexes of glucose were stated on the 90-th and 100-th days of pregnancy (3,44+-/0,63 and 3,38+/-0,26 mmol/l, respectively). High level of cholesterol was stated in course of all pregnancy stages. There was low content of protein in blood in 20% of pregnant sows at the second stage of pregnancy. High indexes of creatine were registered in 80% of animals, urea – in 20% of animals. High content of bilirubin was noted in 23% of pregnant sows, high concentration of lactic acid – in 100% of animals; low content of glucose – in 38%, low level of lipids in blood – in 61%; low level of triglyceride – in 23%

In the conditions of the swine breeding complex in the Republic of Belarus where had been applied the three-way crossing and self-replacement of swine herd there was studied the productivity of swine depending on duration of their embryonic development. There was developed new method of selection replacement gilts which made it possible to select a breeding swine flock with high adaptation abilities to the industrial housing conditions. Research results showed that the duration of pregnancy in the conditions of three-way rotational crossbreeding and self-replacement of swine herd was 114,5 +/- 0,03 days with variance between 103 and 121 days. In the majority of breeding sows (93%) the duration of pregnancy period was within the limits from 112 up to 117 days. Season of a year rendered influence on the duration of sow pregnancy: the longest one was in winter and spring, the shortest – in summer and autumn. With advancing age there was stated the increased duration of pregnancy period. Difference in duration for first-pregnant sows and sows with 8 farrows was 0,51 days. With increase of pregnancy duration there was noted the lowering of multiple fetation, but there was the increasing of live weight of piglets at birth, their growth energy and viability

Analysis of the main indexes of embryo productivity of cow donors with a view to application of progestagenic intravaginal devices in technology of cattle embryo transplantation was realized in the conditions of the Republic of Belarus. Research results showed that application of progestogenic implants independently of the day luteal phase of sexual cycle in schemes of animal treatment made it possible to regulate the folliculogenesis of cows by mean of formation of new wave of follicles growth that could be used in increasing the efficiency of technology of transplantation of cattle embryos. Application of intravaginal devices in schemes of superovulation treatment of cows made it possible to obtain high-grade results of the main indexes of embryo production of donors in technology of cattle embryo transplantation. The technology of application of implant PRID in course of 7 and 9 days in the luteal phase of sexual cycle of donors proved to be the most optimal. It was determined that the indexes of quality composition of embryos, transplantability of fresh and frozen embryos obtained from cows induced by superovulation with application intravaginal devices corresponded to the control indexes. Application of progesterone extracting implants in the schemes of donor cows treatment schemes did not render influence on obtaining of viable animal yield after transplantation of biological material to recipients