Ronen Yehuda

Influence of Campylobacter fetus subsp. fetus on ram sperm cell quality

Campylobacter fetus subsp. fetus infection can occur in female sheep, causing infertility or abortion. Despite extensive research on the effect of these bacteria on female fertility, little research has been done on the influence of C. fetus subsp. fetus on the male factor. Our objective was to examine the influence of C. fetus subsp. fetus on ram sperm. Motility index, percentage of live spermatozoa, mean alphat value (an indication of the chromatin stability of the sperm cell) and percentage of sperm cells expressing the FAS receptor were measured in sperm incubated in the presence or absence of C. fetus subsp. fetus. The motility index and viability of sperm incubated with the bacteria were lower than those of untreated sperm samples after 5 h. In bacteria-incubated sperm cells, the percentage expressing FAS receptor was already significantly elevated at 15 min. Bacteria-incubated sperm showed a greater prevalence of morphological damage. The bacteria were attached to tail and acrosome regions, and the sperm damage was concentrated in both the motility and chromatin regions. Bacteria-infected sperm cells showed a decrease in motility, increase in early acrosome reaction and chromatin damage. Similar effects were induced by incubation of the sperm with supernatants from C. fetus subsp. fetus cultures. Thus this study demonstrates that C. fetus subsp. fetus has a detrimental effect on the quality of ram sperm.

Effect of hCG injection on prostaglandin E concentrations in ram seminal plasma

Ram and bull seminal plasma, respectively, contain 0.5-20 microg PGE/ml and 5-10 ng PGE/ml. To demonstrate that PGE concentrations in the seminal plasma are related to sperm quality and could be affected by hormonal stimulation in vivo, four rams were injected with 500 IU hCG, in and out of season. The rams responded 1 week after hCG with a 1.5- to 4-fold increase in seminal plasma PGE. The PGE peak was temporally separate from the hCG-induced rise in seminal plasma testosterone which was observed after 1 day. Using a simulated cryptochid ram, peaks in seminal fluid PGE were found to be associated with increased sperm velocity and sperm counts. In bulls, PGE concentrations in the seminal plasma of good bulls were significantly higher than that found in poor and cryptorchid bulls.