Quantification of bull sperm characteristics measured by computer-assisted sperm analysis (CASA) and the relationship to fertility.

摘要

In the 1st of 2 experiments, semen was collected on 3 days from 6 bulls, 6 years of age, twice daily at 3- to 4-day intervals. In the 2nd experiment, semen was collected on 4 days at the same interval as in the 1st experiment from 11 bulls, aged 6-11 years, that had extensive breeding information. Standard semen analysis and computer-assisted sperm analysis (CASA) with the Hamilton Thorne IVOS, model 10 unit, were performed on 36 first and second ejaculates in the 1st experiment and on 44 first ejaculates in the 2nd experiment. 16 fields (2 chambers with 8 fields per chamber) were examined per sample. In the 1st experiment, the correlation between sperm concentrations estimated by spectrophotometry and CASA was 0.91 (P<0.01). The percentage of motile spermatozoa among bulls ranged from 52 to 82 for CASA and 62 to 69 for subjective measurements. Thus, CASA provided a better discrimination of the percentage of motile spermatozoa with high repeatability than did the subjective procedure. Bull effectwas much greater than any other variable. Chamber differences were small and so the results for the 2 chambers with 8 fields each were combined. Most CASA variables were correlated (r2 = 0.63-0.68) with bull fertility, defined as 59-day non-return ratecorrected for cow and herd effects. The percentage of motile spermatozoa, however, accounted for only a small fraction of the variation in fertility (r2 = 0.34). Higher r2 values were obtained when 2-5 variables were included in multiple regression equations.