Vie CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. I

SEMINAL CHARACTERISTICS AND FERTILITY
OF STALLIONS

C. VAN DUIJN Jr.
Biophysics Dept., Research Institute for
Animal Husbandry 'SCHOONOORD'
Zeist, The Netherlands

According to Van Duijn's (2,3,4) theory of the
relationship between seminal characteristics and
fertility it is expected that correlations exist
between the logarithm of fertilization results F
and the logarithms of total numbers of spermatozoa
rer ejaculate N y the total number of progress-
ively moving spggfiatozoa N s the percentage of
progressively moving spermE%Xzoa M and the fract-
ion of spermatozoa that are morphologically normal
p. Since according to the theory these relation-
ships follow a linear trend they would provide the
true correlation coefficients, whereas calculations
of Corr. F X N, M and p, respectively, would give
too low values.

This expectation was checked with experimental
data collected previously by Bielafski (1). These
included two groups of stallions with a total number
of 54. The mverage values of seminal characteristics
were ‘available, classified according to different
fertility levels: 0%, 1-25%, 26-50%, 51-75% and
76-100% fertilizations. For the analysis the averaged
means per class of the two groups were used.

There were no data available on longevity of the
spermatozoa, to be expressed as the half-life period
of the number of moving spermatozoa t%(N). However,
because decrease of numbers of moving®spermatozoa
is an exponential process, it can be shown that log M
may be taken as an approximative aequivalent of ?_%N)
if the motility estimations have been performed %
at a constant time after ejaculation. The fertility
criterion t,(N).log N may then be approximated by
(log M).(loé N) for checking the theoretical relation-
ship, although it will obviously be less accurate than
it could have been with direct determinations of the
half-life periods.

The results of the analysis are shown in Table 1.

In the non-logarithmic form all correlations but
ohe are insignificant, whereas in the logarithmic
form even those correlation coefficients that do not
yet reach significance are on the whole much higher
and may be expected to need only some more extensive

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