1 GOAT SEMEN COLLECTION AND PROCESSING BY DR. LOUIS ...

In addition to the role the method of collection plays as discussed above, there are a number
of other factors which influences the size and sperm content of the ejaculate.
A. Seasonal Factors
In bucks and rams, changes in day length influenced testicular activity by modifying the
release of GnRH and thus the gonadotropins. In seasonal breeders, the volume of the ejaculate is
high in the breeding season and decreases in the non-breeding season (Fig. 20). Sperm concentration
follows an opposite trend. However, no seasonal variations in total sperm numbers per ejaculate are
reported. When the volume increases or decreases, the changes of volume are mainly due to changes
in quantities of fluids secreted by the accessory glands and the epididymis which are androgen
dependent. The androgen receptors in target organs need a preliminary preparation in which
prolactin has been implicated. In turn, prolactin secretion is associated with daily photoperiod of
long duration (i.e., spring and summer days at northern latitudes). The latter knowledge was brought
about by studies in rat and sheep, but may well apply to the male goat in which blood plasma
prolactin levels rise in the spring to culminate in summer and drastically decline in the fall, while the
androgen abruptly rise takes place in the middle of the Summer to culminate in the Fall and decline
in the middle of winter.
Figure 20. Seasonal Variations in Volume and Sperm Concentration of Ejaculates
(m ± sd).
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