EFFECTS OF Trypanosoma brucei brucei AND Trypanosoma evansi ON SCROTAL CIRCUMFERENCE, SEMEN CHARACTERISTICS AND HAEMATOLOGICAL PARAMETERS OF YANKASA RAM (Ovis aries Linnaeus, 1978)

The effects of trypanosomosis on the scrotal circumferences and semen characteristics of Yankasa rams were studied for ninety eight days (14 weeks). Sixteen Yankasa rams aged between 24 to 30 months and weighed between 22 to 25 kg were acclimatized for a period of two months in a clean flyproof house and were adequately fed and given water ad libitum. Of the sixteen rams, twelve that were clinically fit for the experiment at the end of the acclimatization were randomLy divided into four Groups: I, II, III and IV, of three rams each. Groups I and II were each challenged singly with experimental T. brucei brucei (Federe strain) and T. evansi (Sokoto strain) respectively, while Group III was challenged with mixed T. brucei brucei and T. evansiparasites (50% of each species in the infective inoculum) and Group IV was left as uninfected control. Each infected ram received 2 mL containing 2 x 10 trypomastigotes via the jugular vein. All the infected groups developed clinical signs typical of trypanosomosis at various prepatent periods, with significant (P<0.05) decrease in values of haematological indices. There was a drastic and significant decrease in scrotal circumferences in the infected rams with significant deterioration (P<0.05) in semen quality of all the infected rams, characterized by decrease in volume or cessation of semen production, a significant (P<0.05) decrease in progressively motile sperm, elevated numbers of dead sperm and significant increase (P<0.05) in spermatozoa morphological abnormalities in all the infected rams. The rams especially in Groups I and III were all deemed unfit for breeding by the end of the 98 days post infection. However, the uninfected rams were healthy and had normal semen characteristics throughout the study period. The results indicate that trypanosomosis due to experimental T. b. brucei or T.evansi or Mixed infections (of both parasites) caused significant decrease in scrotal circumference and severe deterioration in semen quality with resultant infertility in Yankasa rams.