ABSTRACT
The objective of this study was to adopt an accurate in vitro test (sperm DNA damage) to predict
fertility through ram spermatozoa. Semen was collected once a week for 8 collection weeks from six rams of
Rahmani and Romanov breeds, 3 rams from each breed. Semen was evaluated for ejaculate volume, sperm
concentration, progressive motility, livability and abnormality of spermatozoa. DNA damage test was
applied with Halosperm kit. Results showed significant (P<0.05) individual differences in percentages of
abnormality and DNA damage in both breeds as well as in percentages of progressive motility, livability
and total sperm output in Romanove breed. Breed had a significant (P<0.05) effect only on ejaculate volume
and total sperm output, being higher in Rahmani compared to Romanove breed. Sperm abnormality, sperm
cell concentration and DNA damage showed an opposite trend with respect to breed effect. Rams showed
the best semen quality in both breed had the highest conception rate (CR). Mean of CR was higher (P<0.05)
in Rahmani than Romanov breed (88.38 vs. 78.79%, respectively). Percentages of progressive motility and
livability of spermatozoa were negatively correlated (P<0.05) with DNA damage and positively with CR
only in Rahmani breed. In both breeds, DNA damage had (P<0.01) a positive and strong correlation with
percentage of abnormal sperm where it was r= 0.557 in Rahmani and r=0.840 in Romanov. In addition, CR
had a positive correlation with sperm cell concentration in Rahmani and Romanove rams. The correlation
between CR and sperm DNA damage was strong and negative (P<0.01) in both breeds (r=-0.699 for
Rahmani and -0.795 for Romanov). In conclusion, the present study indicated the strong negative
correlations between sperm DNA damage percentage of abnormal spermatozoa and conception rates
especially for Romanov rams which showed lower CR. Thus, in vitro sperm DNA damage test can used for
evaluating fertility, in accompany with standard semen analysis assays.