Biotechnologie, Agronomie, Société et Environnement (Jan 2010)
Influence d'une infection expérimentale à Trypanosoma congolense sur la fonction sexuelle des béliers Djallonké et Sahéliens en zone subhumide
Abstract
Influence of an experimental Trypanosoma congolense infection on the reproductive function of Djallonké and Sahelian rams in subhumid zone. To measure the effect of African animal trypanosomosis (AAT) on male reproductive function, eight 18-24 month old Djallonké (ID; 31.2 ± 2.95 kg) and Sahelian (IS; 41.7 ± 4.64 kg) rams were infected with 104 Trypanosoma congolense. Eight other Djallonké (CD) and Sahelian (CS) rams with similar bodyweight and ages were used as uninfected controls. Four weeks after infection, ID and IS were treated with a trypanocidal drug, while maintained under observation. The evolution of clinical parameters shows a higher aptitude of Djallonké than Sahelian to control the effects of infection. This interbreed difference in susceptibility to AAT was confirmed by the higher weight losses in IS (-31.3 g) when compared to ID (-12.8 g) as to CD and CS rams. The effect of a T. congolense infection consisted in a decreased libido in IS (33 s) when compared to ID (22.1 s) (P > 0.05). The results indicate a significant effect of breed on ejaculate volume (CS: 1.23 ml vs CD: 0.88 ml; P < 0.05). Otherwise, breed did not significantly affect the other spermatic parameters. CD sperm cells concentration (3,293.4 x 106.ml-1), total abnormality rate (15.3%), dead sperm cells rate (13.9%), mobile sperm cells rate (75.5%), individual (3.76) and mass motilities (3.94) did not differ (P > 0.05) from those of CS (respectively 3,481.7 x 106.ml-1; 17.3%; 12.4%; 74.9%; 3.77; 3.36). However, the later produced 26% more total sperm cells than CD (P > 0.05). The infection reduced ejaculate volume by 15.8 and 14.5%, (P > 0.05), production of total sperm cells by 18.2 and 13.3% (P > 0.05) and the rate of mobile sperm cells by 14.2 and 27.9% (P < 0.05) respectively for Djallonké and Sahelian rams. The results show a dysfunctional state of testicles due to the harmful effects of AAT infection, hence the increase in dead sperm cells by 69.8 and 74.3% (P > 0.05) and in the rate of total abnormal sperm cells by 23.6 and 24.1% (P > 0.05) respectively for ID and IS rams when compared respectively to CD and CS animals. Harmful effects often more pronounced in Sahelian breeds during this experiment could indicate a higher susceptibility of this breed to AAT in comparison with Djallonké. One Sahelian ram died two weeks post-infection and azoospermia was observed in another one six weeks after chemotherapy and the disappearance of parasites from the bloodstream.
