The effects of plunging temperature in liquid nitrogen and cryoprotectant dilution methods were evaluated for compacted mouse morulae frozen in 1.5 M ethylene-glycol (E), 1.5M propylene-glycol (P) or 1.4M glycerol (G). Morulae were equilibrated for 10 minutes in cryoprotectant solution and loaded into 0.25 ml straws with cryoprotectant solution in 3 columns (groups E1, P1, G1) or cryoprotectant in the center and PBS in the lateral columns (E2, P2). Straws were cooled at 0.5ºC/min to -25 or -30ºC and plunged into liquid nitrogen. Straws were thawed in water at 22ºC for 20 seconds. Cryoprotectant was diluted in 3 steps for group G1 and in one step for groups E1 and P1 (direct transfer to PBS + 10% FCS) and E2 and P2 (shaken to mix the 3 columns before transferring to PBS+ 10% FCS). Plunging temperature had no significant effect on the proportion of morulae developed to blastocysts in vitro; this proportion was higher (p < 0.0001) in E1 (69.2%) than in E2 (60.3%), G1 (51.9%) and combined for P1 and P2 (46.9%). In second experiment, the proportion of transferred morulae that developed to viable fetuses was lower (p < 0.07) for E1-25 than for E1-30, G1-30, E2-25 or unfrozen (control) embryos (8.7, 20.0, 20.0, 17.4 and 19.8%, respectively). In conclusion, the ethylene glycol diluted directly in PBS (E1) exhibit the highest rate of in vitro embryos development, but based on in vivo embryos development was more efficacious in plunging temperature at -30ºC (E1-30). | Os efeitos das temperaturas de imersão em nitrogênio líquido e dos métodos de remoção dos crioprotetores foram avaliados em mórulas de camundongos congeladas em etilenoglicol (E), propilenoglicol (P) e glicerol (G). Os embriões foram equilibrados em E (1,5M), P (1,5M) ou G (1,4M) por 10 minutos e envasados em palhetas de 0,25 ml com crioprotetor nas três colunas (E1, P1 G1) ou PBS nas colunas das extremidades (E2, P2). As palhetas foram resfriadas a 0,5ºC/minuto até -25 ou -30ºC e imersas em nitrogênio líquido. A descongelação dos embriões foi feita em água a 22ºC por 20 segundos. O crioprotetor dos embriões congelados em glicerol (Gl) foi removido em 3 etapas, dos congelados em etilenoglicol e propilenoglicol com crioprotetor nas 3 colunas (El e Pl) removido diretamente em PBS e dos congelados em etilenoglicol e propilenoglicol com PBS nas colunas das extremidades (E2, P2), após mistura das três colunas dentro da palheta, em PBS. Não houve influência da temperatura de imersão sobre o desenvolvimento embrionário in vitro, observando maior taxa (p < 0,0001) para El (69,2%) que para E2 (60,3%), Gl (51,9%) e a combinação P1 e P2 (46,9%). Para o desenvolvimento in vivo, a taxa de fetos foi menor (p < 0,07) para o grupo E1-25 do que para o Controle; Gl-30ºC; El-30ºC e E2-25ºC. Pode-se concluir que in vitro o melhor crioprotetor foi o etilenoglicol com remoção direta em PBS e que in vivo o etilenoglicol e o glicerol foram semelhantes a -30ºC.

An effort to demonstrate the mechanism of homeostatic alteration of high-producing cows at the period of increasing milking capacity and peculiar features of its changing in the conditions of introduction into cattle diets of carbohydrate containing and carbohydrate compensative additives was realized in the conditions of the Republic of Belarus. In course of the experiment there were used white-and-black breed cows of 3-4 lactations with body weight of 700 kg and milk yield over the last lactation of 7000-8000 kg of milk. Experimental cows in two weeks before the supposed calving were administrated with 50 ml of propylene glycol, 6 g of niacin and 50 ml of glycerin; and in course of 60 days after calving the administration of the additives was realized in doses of 125 ml; 6 g; 50 ml, respectively. Research results showed that application of mentioned above additives rendered the positive effect on cow liver that was proved by the improved hemic function of experimental cows: increasing of quantity of erythrocytes, hemoglobin, and hematocrit