Exogenous energy sources for spermatozoa in cervical mucus of the cow at oestrus.

Bovine spermatozoa have been shown to metabolize exogenous substrates both aerobically and anaerobically (Mann, 1964). Fructose (Mann, 1946) and sorbitol (King & Mann, 1958) have been unequivocally identified in seminal plasma, but evidence for the presence of metabolizable substrates in the cervical mucus rests on much less secure foundations. A number of reports that glucose is present in cervical mucus have appeared and indeed Doyle (1958) proposed to use the presence of glucose in human cervical mucus as an index of ovulation. This test has not attained widespread acceptance although there is a general impression that the sugar is present (see e.g. Moghissi, 1973). The original authority for the presence of glucose in bovine cervical mucus at oestrus is Olds & VanDemark (1957) who used, as others have done since, measurements of reducing value which are appropriate for deproteinized