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A systematic study was made on the semen characteristics of crossbred bull and their changes, if any, during preservation in egg yolk – citrate, Tris and skim milk diluent upto 72 hours.
A total of 72 ejaculates, from five crossbred bulls maintained at A. I. Centre attached to College of Veterinary and Animal Sciences, Mannuthy were utilised for the study.
Immediately after collection semen was subjected to routine evaluation and smears were prepared, stained with Giemsa stain and examined for various types of sperm abnormalities and sperm head biometry. Semen samples were then diluted at the rate of 1:20 in EYC, Tris and skin milk diluent and stored at 50 C. To study the effect of preservation in the above diluents at 0, 24, 48 and 72 hours, motility, various sperm abnormalities and sperm head biometry were observed during the above storage periods.
The overall average concentration and livability of sperm was 1.59 + 0.025 million per cmm and 83.45 + 0.522 per cent, respectively. No significant difference in concentration and livability of sperm was found between bulls.
The overall average initial motility was 83.00 + 1.00 per cent before dilution. During preservation upto 72 hours in EYC. Tris and skin milk diluent sperm motility declined significantly to 57.10, 58.00 and 55.80 per cent respectively. There was no significant variation between the diluent used in maintaining sperm motility but significant difference was noticed between the bulls.
The mean percentage of free normal head, free abnormal head, detached acrosome, pear shaped head, narrow at the base; knobbed head, abnormal contour and underdeveloped head was 2.20 + 0.151, 1.56 + 0.132, 1.26 + 0.180, 1.80 + 0.130, 1.22 + 0.086, 0.80 + 0.122, 1.52 + 0.08 and 0.82 + 0.082 respectively, before dilution. Among all the head abnormalities, detached acrosome increased significantly with the advancement of storage period upto 72 hours irrespective of the diluent used. However, no variation in sperm head abnormalities was noticed between the diluents. All types of head abnormalities varied significantly between bulls.
The average percentage of proximal protoplasmic droplets and middle piece defect was 1.18 + 0.156 and 0.90 + 0.083 per cent respectively, before dilution. They remain unchanged upto 72 hours of storage in all the three diluents. Though, significant difference was found between the bulls, no variation could be noticed between the diluent used.
Simple bent tail and coiled tail showed significant variation between bulls and between the storage periods; mean values being 2.18 + 0.106 and 1.24 + 0.102 per cent, respectively, before dilution. They increased significantly at 72 hours of storage in EYC, Tris and skin milk diluent, the mean values being 2.74 + 0.150, 2.74 + 0.050 and 3.06 + 0.037 per cent, respectively, for simple bent tail and 1.44 + 0.092, 1.44 + 0.092 and 1.48 + 0.215 per cent, respectively for coiled tail. Though, in the case of simple bent tail significant variation was found between the diluents, no such variation could be noticed in case of coiled tail.
The average length and breadth of sperm head was found to be 9.51 and 4.72 microns, respectively, before dilution, No significant variation in spermatozoan head length and breadth could be noticed as the storage period advanced to 72 hours. There was no significant variation between the diluents. However, significant variation was found between the bulls. Thus it could be inferred that all the three diluents were found to be equally good for preservation of bull semen upto 72 hours at 50 C.