Avaliação de diferentes crioprotetores intra e extracelulares na criopreservação de sêmen de touros / Evaluation of different intra and extracellular cryoprotectants on bull semen cryopreservation

Em um delineamento experimental usando o fatorial 3x2, três crioprotetores internos, glicerol (GLI), etilenoglicol (EG) e dimetilformamida (DMF), e dois externos, gema de ovo (GEMA) e lipoproteína de baixa densidade (LDL), avaliaram-se a motilidade ao descongelamento de GLI-GEMA 53,9±1,96, sendo superior aos demais tratamentos (P<0,05). Na avaliação de morfologia ao descongelamento, não houve diferença (P>0,05) entre os tratamentos EG-GEMA 68,3±1,58, EG-LDL 72,2±2,39 e DMF-GEMA 68,7±1,67 que foram mais altos que os demais (P<0,05). A avaliação de integridade de membrana por fluorescência ao descongelamento GLI-GEMA 34,2±2,28 e EG-GEMA 30,9±1,32 não diferiram entre si (P>0,05), mas foram mais elevados que os demais (P<0,05), enquanto que a HOST dos tratamentos DMF-GEMA 13,6±1,30 e DMF-LDL 9,8±0,78 diferirem entre si (P<0,05) e foram mais baixas que as demais (P<0,05). O uso de etilenoglicol associado à gema de ovo pode ser uma alternativa ao uso de glicerol nos protocolos de congelamento de sêmen de touros.(AU)

The experiment was designed as 3 x 2 factorial design, with three internal cryoprotectants, glycerol (GLY), etileneglycol (EG) and dymethilformamide (DMF) and two external, egg yolk (YOLK) and density low lipoproteina (LDL). The motility at thawing for GLY-YOLK (53.9±1.96) was higher than other treatments (P<0.05). The percentage of cells with normal morphology at thawing was not different between EG-YOLK (68.3±1.58), EG-LDL (72.2±2.39) and DMF-YOLK (68.7±1.67), but they were higher than the others (P<0.05). The evaluation of membrane integrity through fluorescent probes at thawing indicate that GLY-YOLK (34.2±2.28) and EG-YOLK (30.9±1.32) were not different (P>0.05), but were higher than the others (P<0.05). The evaluation of membrane integrity through hypoosmotic swelling test (HOST) indicate that DMF-YOLK (13.6±1.30) and DMF-LDL (9.8±0.78) were different (P<0.05) and lower than the others (P<0.05). The use of ethylene glycol associated to egg yolk can be a viable alternative to the use of glycerol in bull semen freezing protocols.(AU)

Aumento da qualidade de ovócitos recuperados por punção folicular de vacas submetidas previamente à superovulação / Increasing of oocytes quality retrieved by ovum pick-up from cows previously superovulated

O objetivo deste estudo foi avaliar a qualidade de ovócitos obtidos por meio de punção folicular de vacas doadoras submetidas à superovulação após a coleta de embriões. Foram utilizadas 22 vacas mestiças (Bos taurus x Bos indicus), que foram divididas em dois grupos: 1) grupo-controle (GC; n = 11), composto por vacas em fase aleatória do ciclo estral, pois não sofreram nenhum tratamento hormonal, e 2) grupo corpos lúteos (GCL; n = 11), vacas que haviam sido utilizadas em um programa de superovulação e coleta de embriões. Todas as vacas foram submetidas à punção folicular ovariana a cada sete dias após a coleta de embriões do GCL, totalizando cinco seções de punção por grupo. Houve uma maior taxa de recuperação de ovócitos de qualidade I e II no GCL do que no GC (28,6 e 6,4%, respectivamente; P < 0,001). Os resultados indicam que ovócitos recuperados após um programa de superovulação e coleta de embriões apresentam melhor qualidade do que ovócitos coletados em fase aleatória do ciclo estral.

The aim of this study was to evaluate the oocyte quality retrieved by ovum pick-up (OPU) after the embryo collection in cows subjected to superovulation procedure. Twenty two crossbred cows were separated into two groups; 1) Control Group (CG; n = 11), cows in random stage of the estrous cycle that did not received any hormonal treatment and 2) Corpus Luteum Group (CLG; n = 11), cows that had been used in a superovulation protocol and embryo collection. All cows were subjected to OPU procedure every 7 days after embryo collection of the CLG. The CLG had higher rate of oocytes quality I and II retrieved than the CG (28.6 e 6.4%, respectively; P < 0.001). The results indicate that oocytes retrieved from cows subjected to protocols of superovulation and embryo collection are of better quality than oocytes collected in random stage of the estrous cycle.

Effect of circulating progesterone on in vitro developmental competence of bovine oocytes

This study evaluated the effects of systemic progesterone concentration on oocyte quality and in vitro embryo production. Oocytes were retrieved from 15 crossbred cows (Bos taurus x Bos indicus). These cows were randomly allocated into three groups to provide low; high, or very low (LP4, HP4 and VLP4, respectively) plasma progesterone concentrations and received either a previously used CIDR, two new CIDR devices, or no progesterone treatment (Day 0). The CIDR devices were replaced every 8 days along with 150 µg of D-cloprostenol injections. The ovum pick-up (OPU) procedure was performed every 4 days from Day 4 to 24. Simultaneous to OPU procedure, plasma was collected to measure progesterone and on Day 18, serial blood samples were collected to assess the pattern of LH release. Hormone concentrations were analyzed by ANOVA and the binomial variables were analyzed by Chi-square. Plasma progesterone concentration was higher in the HP4, intermediate in the LP4, and lower in the VLP4 group (3.6, 1.6, and 0.5 ng/ml; P < 0.05). Plasma LH was higher in the LP4, intermediary in the VLP4, and lower in the HP4 group (1.6, 1.0, and 0.8 ng/ml). A greater percentage of viable oocytes (grades I to III) was retrieved from LP4 (79.4%; 131/165) than from the HP4 (68.4%; 119/174) group (P = 0.07); the VLP4 group did not differ from the others (72.3%; 60/83). Furthermore, the blastocyst production and blastocyst rate was higher in LP4 (1.3 ± 0.4; 28.2%), than in HP4 (0.8 ± 0.4; 16.0%) or the VLP4 (0.4 ± 0.4; 15.0%) group (P = 0.06 and 0.03 for blastocyst production and rate, respectively). In conclusion, intermediate plasma P4 concentration that results in higher circulating LH in cows may improve in vitro embryo production.(AU)

Effect of circulating progesterone on in vitro developmental competence of bovine oocytes

This study evaluated the effects of systemic progesterone concentration on oocyte quality and in vitro embryo production. Oocytes were retrieved from 15 crossbred cows (Bos taurus x Bos indicus). These cows were randomly allocated into three groups to provide low; high, or very low (LP4, HP4 and VLP4, respectively) plasma progesterone concentrations and received either a previously used CIDR, two new CIDR devices, or no progesterone treatment (Day 0). The CIDR devices were replaced every 8 days along with 150 µg of D-cloprostenol injections. The ovum pick-up (OPU) procedure was performed every 4 days from Day 4 to 24. Simultaneous to OPU procedure, plasma was collected to measure progesterone and on Day 18, serial blood samples were collected to assess the pattern of LH release. Hormone concentrations were analyzed by ANOVA and the binomial variables were analyzed by Chi-square. Plasma progesterone concentration was higher in the HP4, intermediate in the LP4, and lower in the VLP4 group (3.6, 1.6, and 0.5 ng/ml; P < 0.05). Plasma LH was higher in the LP4, intermediary in the VLP4, and lower in the HP4 group (1.6, 1.0, and 0.8 ng/ml). A greater percentage of viable oocytes (grades I to III) was retrieved from LP4 (79.4%; 131/165) than from the HP4 (68.4%; 119/174) group (P = 0.07); the VLP4 group did not differ from the others (72.3%; 60/83). Furthermore, the blastocyst production and blastocyst rate was higher in LP4 (1.3 ± 0.4; 28.2%), than in HP4 (0.8 ± 0.4; 16.0%) or the VLP4 (0.4 ± 0.4; 15.0%) group (P = 0.06 and 0.03 for blastocyst production and rate, respectively). In conclusion, intermediate plasma P4 concentration that results in higher circulating LH in cows may improve in vitro embryo production.