LEVELS OF SOME NORMAL CONSTITUENTS OF BULL SEMEN DURING REPETITIVE EJACULATION

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Abstract
Four consecutive ejaculates were collected within 1 hr, at weekly intervals for 4 weeks, from each of 5 mature Holstein bulls to determine the influence of repetitive ejaculation on the levels of some seminal constituents. The pH of the fresh semen and the concentrations of fructose and citric acid in the seminal plasma increased (P<0.01) while the concentration and total amount of free amino nitrogen declined from 1st to 4th ejaculates (P<0.01). Repetitive ejaculation did not significantly influence the concentrations of protein and zinc in the seminal plasma (P0.20) or the total citric acid and fructose per ejaculate (P0.20). Moving boundary electrophoresis of the proteins and agar-gel-diffusion studies of the antigens in seminal plasma revealed that each protein component observed in 1st ejaculates was also found in 4th ejaculates. However, the proportion of the protein components in 4th ejaculates differed from that in 1st ejaculates. The results suggested that the total contribution of the seminal vesicles to the seminal plasma was relatively constant, but their relative contribution increased, from the 1st to the 4th ejaculate, at least partly at the expense of the contribution of the epididymides.