Criopreservação do sêmen ovino em pellets com etileno glicol

Abstract

Com a finalidade de avaliar a eficácia do etileno glicol para a preservação do sêmen ovino, utilizou-se 16 pools de sêmen, sendo cada um dividido em quatro alíquotas com concentrações de 0,3M, 0,5M e 0,7M de etileno glicol par a comparação com 0,72M de glicerol. A avaliação do sêmen por teste de termo-resistência demonstrou que a motilidade inicial, final e vigor final foram semelhantes para 0,5M de etileno glicol e 0,72M de glicerol, e superiores aos demais tratamentos. No entanto, o grupo que utilizou o etileno glicol em 0,5M proporcionou uma melhor proteção acrossomática. Setenta ovelhas divididas em três grupos (etileno glicol 0,5M, glicerol 0,7 2M e sêmen fresco), foram submetidas a sincronização de cios, inseminação, pela via cervical e diagnóstico de gestação aos 45 dias de gestação por ultra-sonografia. Não foram observadas diferenças significativas entre o grupo do etileno glicol com os do sêmen fresco e glicerol, porém verificou-se diferença entre os grupos do sêmen fresco e do glicerol. Considerando os resultados obtidos, conclui-se que o etileno glicol utilizado na concentração de 0,5M propicia motilidade e vigor semelhantes ao glicerol (0,72M), porém proporciona uma melhor proteção acrossomática. _______________________________________________________________________________ ABSTRACT

The aim of the present study was to verify the efficiency of ethylene glycol for freezing ram semen. A total of 16 pools of semen was used and each pool was divided in four fractions, which were frozen with ethylene glycol (in concentration of 0.3M, 0.5M or 0.7M) or glycerol (0.72M; control group). The percentage of motile spermatozoa after thawing (initial motility) and after 5 hour of incubation at 37°C (final motility) as well as the final sperm vigor were similar after freezing with ethylene glycol (0.5M) and glycerol (0.7 2M). The other concentrations of ethylene glycol resulted in lower sperm motility and vigor. However, ethylene glycol, in the concentration of 0.5M, was able to increase the number of sperm with intact acrosomes. Seventy ewes were divided into three different treatments (ethylene glycol-0.5M, glycerol-0.72M and fresh semen). The estrous were synchronized and the ewes were inseminated by cervical technique. Forty-five days after finishing the artificial insemination program, pregnancy diagnosis was performed by ultrasound. The pregnancy rate was similar when the ethylene glycol treatment group was compared to the glycerol and fresh semen. However, the percentage of pregnancy was higher in the group of ewes inseminated with fresh semen than with semen frozen with glycerol (p<0.0003). Considering these results, we can conclude that ethylene glycol in a concentration of 0.5M is efficient for freezing ram semen, allowing post-thaw sperm motility similar to glycerol (0.72M) but with higher number of intact acrosomes.