Abstract :
Seasonal changes of scrotal circumference, blood plasma testosterone concentration and
semen characteristics were studied over a period of 12 months in rams of the Hungarian
Black Racka breed. Significant differences between seasonal averages of the parameters
measured were established in multiple cases. As regards changes in scrotal circumference,
the highest average value obtained in September (31.92 cm) exceeded the lowest
value measured in January (22.08 cm) by 44.7%. It has been found that the season significantly
affects the testicular dimensions (r = 0.87, P < 0.01). Significant correlations were
found between scrotal circumference and day length (r = 0.43, P < 0.05) as well as between
scrotal circumference and monthly average temperature (r = 0.73, P < 0.01). The lowest
blood plasma testosterone (T) level (2.31 ± 0.14 ng/ml) was measured in winter and the
highest in autumn (17.81 ± 0.7 ng/ml). Significant differences between the seasonal values
were observed on multiple occasions. The GnRH-provoked maximal testosterone level
(Tincr) was found in autumn, in the breeding season (54.02 ± 3.78 ng/ml). A significant correlation
was found between T and Tincr on the one hand and scrotal circumference on
the other (r = 0.62, P < 0.01 and r = 0.69, P < 0.01, respectively). Ejaculate volume tended
to increase from spring (0.52 ± 0.03 ml) to autumn (0.88 ± 0.03 ml). The lowest sperm
concentration (4.92 ± 0.13 × 109/ml) was measured in winter and the highest in summer
(6.56 ± 0.21 × 109/ml) (P < 0.001). Total sperm count per ejaculate was the lowest in
spring (3.15 ± 0.23 × 109/ml) and the highest in autumn (5.22 ± 0.45 × 109/ml) (P < 0.001).
Sperm motility was at a low level in February (4.42 ± 0.20) and subsequently showed
the highest values in the summer months, with similar monthly averages in June–August
(5.00 ± 0.00, P < 0.001). The percentage of abnormal spermatozoa was the highest in winter
(18.48 ± 3.23%) and the lowest in autumn (7.95 ± 1.58%) (P < 0.001), and it was significantly
higher in February than in other months of the year (22.17 ± 1.61%, P < 0.001–P < 0.02). The
lowest number of deformed spermatozoa was observed in October (6.15 ± 0.72%).
