Characterization of the
testicular semen of the African catfish, Clarias gariepinus
(Burchell, 1822), and its short-term storage
N. Mansour, F. Lahnsteiner, B. Berger-2004
Aquaculture
Research, 35(3): 232-244
Abstract:
Semen of the African catfish, Clarias gariepinus
(Burchell, 1822), was investigated with respect to its cellular composition,
sperm cell density, maturation grade, motility and fertility. Storage
conditions were tested, whereby sperm viability was assessed by measurement
of the motility after activation and by fertility tests. Testicular semen
differed in its composition, i.e. the sperm density and numbers of
spermatids, according to the maturity grade of the testis. Two semen types
could be distinguished: semen type I was characterized by high sperm
densities and low numbers of spermatids and semen type II had lower sperm
densities and higher numbers of spermatids. Two semen types did not differ
in motility and fertility (when adjusted for differences in sperm density).
During storage, the sperm viability was influenced by the sodium
concentration of the storage medium, temperature, membrane stabilizers as
bovine serum albumen (BSA) or hen egg yolk, antibiotics and oxygen. Semen
viability was maintained best when it was diluted at a ratio of 1:5 in
storage solution (150 mmol L-1 NaCl, 2.5 mmol L-1
KCl, 1 mmol L-1 CaCl2, 1 mmol L-1
MgSO4, 20 mmol L-1 Tris (pH 8.5) and 0.5%
BSA or 0.5% hen egg yolk) and stored at 4 °C. Oxygen gassing and addition
of antibiotics (1 mg mL-1 gentamycine sulphate) to the
storage solution affected the two semen types in different ways. Antibiotics
had no effect on type I semen, but had a positive effect on type II semen.
Oxygen gassing had a positive effect on type I semen but a negative effect
on type II semen.
(Institute for Zoology, University of Salzburg,
Hellbrunnerstrasse 34, 5020 Salzburg, Austria. E-mail of F. Lahnsteiner: franz.lahnsteiner@sbg.ac.at)