Effect of propylthiouracil on puberty initiation and semen production in broiler breeder roosters

This experiment was conducted to study the effect of induced transient hypothyroidism on pubertal initiation, histological traits of testis and semen quality in breeder roosters. A total of sixty-six broiler breeder male chicks were randomly assigned to two experimental groups of control or hypothyroidism in a completly randomized design with three pens per group. In hypothyroidism group, chicks were fed dietary treatment of 0.1% propylthiouracil from 6 to 12 week of age. Body weight, thyroxin and testosterone concentrations were measured at 3-week intervals from 6 to 18 and also at 26 week of age. Histological caracteristics and the expression of connecxin 43 gene in testis were assayed in experimental groups and semen quality was evaluated for 10 weeks after photostimulation. Connexin 43 gene expression was higher in control group (1.181) than hypothyroidism one (0.782) at 18 week of age (P<0.05) and was similar at 26 week of age (P>0.05). Semen volume was greater in hypothyroidism group (0.46 ml) than that of control one (0.39 ml). Also, sertoli cell number was greater in hypothyroid group at 18 (159.9 /mm2) and 26 (165.9 /mm2) week of age than that in control group (P 0.05). Also, relative testis weight was greater in hypothyroidism group (749 mg/100gBW) than control group at age 26 week of age (P<0.05). Therefore, addition of propylthiouracil in breeder male chicks diet in prepubertal period, probably resulted in higher sertoli cell number and testicular weight via delay in puberty.