Abstract
1. Fractionated semen was diluted in a ratio of 1:1 or 1:2 with a specially prepared buffer diluent consisted of 3.24g of skim milk, 1.62g of glucose, 0.28g of sodium bicarbonate, 0.36g of Tris, 0.23g of glycine, and 100ml of distilled water, and adjusted to a pH of 7.2 by adding 6% citric acid solution.
The diluted semen was stored in two ways: one being gradual cool-down to 15°C spending 4 hours, by means of immersion in a beaker containing luke-warm water and storage in a low temperature incubator (15°C), followed by further storage at 15°C, while the other being immersion in a thermos containing warm water, followed by storage in a refrigerator (3-5°C) with gradual lowering of temperature down to 5°C spending approx. 24 hours, and then kept stored at 5°C.
The progress in motility change of the sperm was comparatively evaluated with the two sample groups. The test on the activity and livability of the sperm was made by the microscopic examination of the stored semen following warming and shaking for 20-30 minutes at 37°C.
The motility of the sperm stored at 15°C was found to be better than that of the semen stored at 5°C for the initial 3 days of the continued storage, but was sharply lowered on the 4th day.
The semen stored at 5°C were certainly showed less motility for the initial period of storage than that of the semen stored at 15°C, dut further lowering of motility was not noted, maintaining up until the 7th day the active livability of semen which could be used for insemination.
2. The boar semen stored at 5°C for 1-7 days were warmed and shaken at 37°C for 20 minutes in order to infuse the semen which raised the temperature up to 37°C and then restored their motilities.
Of the 17 sows and 13 gilts tested, 13 sows and 9 gilts, 22 in total, were successfully concieved and duly farrowed. The conception rate was 73.3%. The mean litter size was 8.5, 10.8 for sows and 5.2 for gilts, respectively. No trend of reduction in conception rate or litter size was noted with longer storage of the diluted semen.
