Effect of Tribulus terrestris Extract on Sperm Motility, Testosterone Concentration and Relative Expression of Catsper Gene in Older Male Broiler Breeder

The aim of this study was to investigate the effect of adding thistle extract to the basal diet on sperm motility and the relative expression of Catsper gene in the testes of older broilers due to the role of this gene in normal sperm motility. A total of 50 Ross 308 broiler roosters at 47 weeks of age were randomly assigned to five groups (n = 10) and were daily feed with a basic diet containing different levels of Tribulus terrestris including: 1) 0 mg of Tribulus terrestris (control), 2) 5 mg of Tribulus terrestris (Kh-5mg), 3) 10 mg of Tribulus terrestris (Kh-10mg), 4 ) 15 mg of Tribulus terrestris (Kh-15mg), and 5) 20 mg of Tribulus terrestris (Kh-20mg) per kg of body weight for 13 weeks. All roosters were weekly sampled to assess motility of sperm. At the end of the experiment, in order to measure testosterone concentration and evaluate the expression of Catsper gene, seven roosters were randomly slaughtered from each treatment and their testes were sampled. Results showed that Tribulus terrestris feeding improved total sperm motility in Kh-5, Kh-10, Kh-15 and Kh-20 groups by about 6, 4, 3 and 5%, respectively, compared to the control group (P<0.05). Plasma testosterone concentrations were not statistically significant between treatments (P <0.05).  Relative expression of Catsper gene in roosters receiving 5 mg level of Tribulus terrestris tended to increase compared to the control group (P = 0.09); however, at doses of 10 and 15 mg of Tribulus terrestris extract showed a significant difference (P <0.05). But with a dose of 20 mg of thistle extract did not show a significant difference (P<0.05). In summary, in this study, feeding thistle extract at the level of 5 mg increased sperm motility and expression of Catsper gene (one of the genes responsible for sperm motility).