Abstract
The present experiment was conducted to determine the temperature and time of sperm preparation described by Cheng (1985) on in vitro fertilization of sheep. Method A was followed by that of Cheng (1985) except 1 h storage at a concentration of 1×108 spermatozoa /ml in modified 199-sheep serum medium (pH 7.4) at 39°C under 5% CO2 in air. In methods B and C, the sperm suspension at a concentration of 2×108 cells/ml in 2 ml of the medium (pH 7.8) was kept for 40 min either at 39°C under 5% CO2 in air or room temperature (20°C) under an aerobic condition. Follicular oocytes obtained from ovaries stimulated with FSH or from ovaries of animals killed at an abattoir, were matured in vitro.
In vitro maturation rate was 92.7% (153/165). Fertilization rates were 85.2%, 74.5% and 80.4% for methods A, B and C, respectively. There was no significant differences in the fertilization rates among and between the methods. The present results indicated that temperature (39°C or 20°C) for the high pH treatment was not an important factor, and that the high pH treatment for 40 min might be not necessary if the final sperm suspension (1 × 106 cells /ml) in the medium (pH 7.4) was stored at 39°C for 1 h before in vitro insemination.
