Vle CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. Il

EFFECT OF AGING OF BOAR SEMEN ON THE DNA
CONTENT OF LIVE AND DEAD SPERMATOZOA

A. S. ANAND@ and N. L. FIRST
University of Wisconsin, Madison, Wisconsin, U. S. A.

Embryonic losses are known to result from the fertilization of
ova by aged spermatozoa8,3 or temperature damaged spermatozoa’. It
has been hypothesized that this may be due to damage or loss of gen-
etic material (DNA)9. Direct proof of a relationship between DNA
loss or damage and embryo loss is not available. Since it is believed
that only a live spermatozoon is capable of fertilizing an ovum A
would be desirable to know which kind of spermatozoa loses DNA, addi-
tionally if dead cells are low in DNA, spermatozoal populations of
differing DNA content could be constructed and used in breeding
studies to determine the relationship between DNA and embryo loss.

The purpose of this study was to determine the effect of aging
of boar semen on the DNA content of live and dead spermatozoa.

METHODS. For this study, aged spermatozoa are those which have been
Thoubated with boar seminal plasma and physiological saline of pH

7.0 at 370C. for 12 hr. Only the spermatozoa-rich fractions of semen
were collected. Each trial was carried out by using split ejaculates
(fresh vs. aged). Each split-ejaculate was further subdivided into
two aliquots containing live + dead (unfiltered) and live (filtered)
spermatozoa, respectively. The live spermatozoa were obtained by
filtering the extended semen-aliquot through a glass-bead columnl.
Both the percent motile and the percent live spermatozoa in the un-
filtered and the filtered aliquots of fresh and aged ejaculates,
respectively, were determined. The DNA quantitation was carried out
by color reaction with diphenylamine following extraction with tri-
chloroacetic acidl. The study involved four boars, each replicated
twice in a factorially designed experiment. The data were analyzed
by conventional analysis of variancelO.

RESULTS. The results of the present study are presented in the
Tables (1, 2 and 3). In each trial, the aged-unfiltered spermatozoa
consistently contained less DNA (table 1). Also, the DNA loss after
aging was from the dead spermatozoa. The glass-bead filtration
system effectively separated live from dead spermatozoa as evidenced
by the fact that there were significantly (P £.01) more motile and
live spermatozoa in the filtered than in the unfiltered population of
aged spermatozoa (table 2 and 3). There was a significant difference
between boars in the DNA content of their spermatozoa.

 

8present address: Wisconsin State University, Oshkosh, Wisconsin

1209