Abstract
In the fowl, the relationship between the dilution rate and the fertility of semen have beer reported by some workers but there is very little information available in the duck.
In the present experiments, semen was collected electrically; a composite sample from five 8-month-old drakes was diluted 5 times with the fowl egg-yolk citrate buffer, gradually cooled to 5°C withir a half hour and stored in a refrigerator at 5°C. Thirty ducks of 8-months of age were divided into flocks, each consisting of 6 ducks ( Flock I to V). Each diluted semen sample was injected simultaneously to each flock with a dose of 0.3 ml. per bird. Fertility tests were made with the semen samples stored for 0, 24, 48, 72 and 96 hours respectively.
The results of the last two gronps were quite negative, no fertile egg being produced ; thence the results obtained in Flock IV and V were omitted from Table 1. Results are summarized as follows:
1. In this medium the semen injected immediately after collection showed 100 percent daily fertility with a slight intermediate decreasing of the rate from the third to fifth day following insemi-nation. The fertility potential was maintained until the twelfth day after insemination (Table 1, Flock I).
2. The Semen of 24-hour storage showed 83.3 percent fertility on the third day following insemination; the fertility potential was maintained until the nineth day (Table 1, Flock II).
3. The daily fertility of the semen stored for 48 hours was almost the same as that of the semen stored for 24 hours. However, the duration retaining the fertility potential was quite different; it was maintained only for 5 days in the case of 48-hour storage (Table 1, Flock III).
