Effect of different glycerol concentrations on freezing of buck semen

Abstract

With the object of studying the effect of different concentrations of glycerol on post-thaw motility and fertility of frozen buck semen, five Malabari crossbred (Alpine x Malabari) bucks maintained at Artificial Insemination Centre and 75 does in heat, brought to the A. I. centre, College of Veterinary and Animal Sciences, Mannuthy, Thrissur were used. The average volume of semen was 0.71 ± 0.02 mI. Semen volume varied significantly between bucks. The average colour index was creamy, density was DDDD and the mass activity was ++++. The average pH of semen was 6.85 ± 0.01. The average sperm motility percentage was 85.83 ± 1.05. Motility percentage varied significantly between bucks. The average sperm concentration was 2842.33 ± 153.93 millions/mI. Highly significant difference in sperm concentration was noted between bucks. The average live sperm percentage was 91.03 ± 0.56. There was highly significant difference in live sperm percentage between bucks. Significantly higher percentage of sperm motility was noted in spermatozoa with seminal plasma than in spermatozoa without seminal plasma at 60 minutes of incubation. Slight increase in motility percentage was noted for spermatozoa with and without seminal plasma at 10 minutes of incubation. From 10 minutes to 60 minutes motility was gradually decreasing. Between bucks there was highly significant difference in sperm motility of incubated spermatozoa. Live sperm percentage was significantly higher for spermatozoa without seminal plasma at all time periods of cold shock. There was a rapid reduction in live sperm percentage at five minutes of cold shock. The live sperm percentages between bucks were significant at different time periods except at 10 minutes and 30 minutes of cold shock. The average time taken for reduction of methylene blue by spermatozoa with and without seminal plasma were 173.16 ± 8.77seconds and 197.00 ± 9.97 seconds respectively. Significant difference was noted in methylene blue reduction time between bucks. Average percentage sperm motility after washing was 76.71 ± 0.79. Maximum percentage motility after glycerolisation was obtained in six per cent glycerolated semen (67.85 ± 1.39). There was highly significant reduction in motility percentage after glycerolisation. Maximum post-thaw motility was obtained in six per cent glycerolated extender (42.00 ± 1.84). Highly significant reduction in motility percentage was noted after freezing. The conception percentage and kidding percentage were 47 .36 and 43. 85 respectively. Average gestation length was 149.85 ± 4.45 days. The number of kids per kidding averaged 1.7. Percentage of male and female kidsborn were 51.16 and 48.83 respectively. From this study it could be inferred that Tris extender with six per cent glycerol was superior to Tris extender with four per cent, five per cent or seven per cent glycerol for better post-thaw motility and fertility of frozen buck semen.