Spermatogenic Capacity of the Male Bovine. I. A Measurement Technique

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Abstract
A series of partial exhaustions (10 consecutive ejaculates within 90 minutes) with 1.5-4-year-old dairy bulls showed that 7 days were adequate for a severely depleted sperm supply to be completely restored. Extending the interval between partial exhaustions to 30 days resulted in no more spermatozoa than allowing an interval of seven days. The daily rate of sperm production in 6 two-year-old Holstein bulls, as indicated from partial exhaustions at 1-, 4-, and 7-day intervals, was 1949 billion. It was calculated that each gram of testis was producing a minimum of 2,880,000 sperm cells each day (20 x l06/week). In situ measurements with a set of calipers provided a satisfactory estimate of testis size. The correlation between testis weight and the measurement of length x width of testis was r = 0.94. Data on 11 bulls showed a correlation of r = 0.80 between testes-epididymides weight and the total number of sperm ejaculated in 10 consecutive ejaculates. The correlation between seminal vesicles weight and total volume of semen produced in 10 consecutive ejaculates was r = 0.73. Partial exhaustion at various intervals appears to be an effective means of evaluating experimental treatment effects upon the spermatogenic capacity of the male.

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