The chemical composition of the pre-sperm fraction of bull ejaculate obtained by electrical stimulation

Abstract

When semen is ejaculated, its different components are not discharged all at once, but follow one another in a definite order of sequence. It has been possible to demonstrate this clearly in man, through the application of the so-called 'split-ejaculation' method. In man, the ejaculation is initiated by the secretion of Cowper's gland; the prostatic secretion comes next, to be followed by the sperm and the vesicular secretion (Huggins & Johnson, 1933;MacLeod & Hotchkiss, 1942). According to more recent data provided by Lundquist (1949), less than 10 % of the human ejaculate is contributed by the sperm and epididymal secretion, 12-8-32-5 % by the prostatic secretion, and 46-3-80-4 % by the vesicular secretion.In experiments on animals the technique of fractionate collection has been successful in species in which the ejaculation is physiologically a slow process. An animal well suited to this type of experimental approach is the boar, with an ejaculation period lasting up to 30 min. According to McKenzie, Miller & Bauguess (1938), less than 5 % of the boar e j aculate is made up by the sperm and the epididymal secretion, whereas the urethral glands contribute up to 70 %, Cowper's glands 10-25 %, and the seminal vesicles 15-20 %, of the total ejaculate. Somewhat similar conditions prevail in the stallion (Lambert & McKenzie, 1940; Day, 1940).In the bull, however, unlike in the boar and stallion, the ejaculation is rapid and is completed within a few seconds. Therefore, it is not practicable to collect separate fractions of bull semen ejaculate by means of the artificial vagina. As an alternative method, several investigators have applied to bulls the massage method of collection (cf. Anderson, 1945). However.for the purpose of distinct fractionation, specimens obtained in this manner were seldom of practical value.In the present investigation, use has been made of the electro-ejaculation method, developed by Thibault, Laplaud & Ortavant (1948). By applying electrical stimulation, we have been able to collect and examine two main well-defined fractions of bull semen, an early one during the initial phase of stimulation, very copious and completely spermfree, and following upon it, a later one, containing the sperm. We have devoted our attention to a study of the chemical composition of the pre-sperm Journ. Agric. Sci. 43 fraction; furthermore, the findings made with this secretion were compared with results obtained on the sperm-containing fraction, as well as with bull semen specimens collected in the ordinary way, without electrical stimulation, and occasionally also with the seminal vesicle secretion collected from the glands of freshly killed bulls. EXPERIMENTALThe collection of bull semen fractions by electrical stimulation was carried out according to the technique described in detail by Thibault et al. (1948), with the aid of a rectal electrode, which was kindly made available to one of us (L.E.A.R.) by Dr Thibault. The ejaculate was collected into several separate glass tubes; the samples which were found ...

An Effect of Bovine Seminal Plasma on the Impedance Change Frequency of Epididymal Spermatozoa Collected From the Living Bull

“…However, when the bull with a fistula was stimulated by applying a low voltage across a small bipolar rectal probe, a clear fluid (esp) was obtained from the penis which was fructose-free and, virtually, free from nitrogen and therefore did not contain vesicular secretion. The esp had a Ca and Mg concentration and pH similar to the pre-sperm fraction of a complete electric ejaculation as defined by Lutwak-Mann & Rowson (1953); that fraction did not contain vesicular secretion.…”

On the composition of boar semen

“…In man, the seminal vesicle secretion is well known to be ejaculated immediately after the sperm (Huggins & Johnson, 1933;Lundquist, 1949). In the bull, Lutwak -Mann & Rowson (1953) were able to obtain with the aid of electric stimulation at least two fractions, the first consisting of a copious sperm-free and fructose-free urethral secretion, the second containing the sperm but also some fructose and citric acid; occasionally, they obtained a third fraction consisting almost entirely of the seminal vesicle secretion, and very rich in fructose and citric acid. SUMMARY 1.…”

The biochemistry of semen

“…Obviously, such incomplete ejaculations create a further complication in the assessment of analytical results obtained with semen, at any rate in those species in which the ejaculation is a fractionated one. But even in the bull where under physiological conditions ejaculation appears to be instantaneous, the 'splitejaculate method' applied by Lutwak-Mann and Rowson (1953) with the aid of electric stimulation, demonstrated the occurrence in electrically-induced ejaculates, of at least two distinct fractions; of these, the first was a copious sperm-free fraction, slightly viscous, colourless, and of urethral origin, in which there was no fructose or citric acid and very little protein; the next was a creamy spermcontaining fraction, followed by, or more often mixed with, a yellowish-coloured post-sperm fraction which represented an almost pure secretion of the seminal vesicles, with a characteristically high content of fructose, citric acid, and 5-nucleotidase. Criteria for the rating of semen quality General medical and veterinary experience indicates that the successful fertihzation of the ovum and initiation of pregnancy, while it is brought about primarily by the spermatozoa present in an ejaculate, demands nevertheless the attainment of certain qualitative and quantitative standards by the semen. We should therefore, be able to define what constitutes normal fertile semen, and what criteria if any, can be applied in the appraisal of ejaculated semen.…”