پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 2 2017 08 23 The effect of dietary Letrozole on plasma gonadotropin concentrations and some testicular histology parameters in 40 weeks old broiler breeder rooster The effect of dietary Letrozole on plasma gonadotropin concentrations and some testicular histology parameters in 40 weeks old broiler breeder rooster 175 183 63031 10.22059/ijas.2017.231769.653523 FA Emad Abdulgabbar Ali Ph. D. Candidate, Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Mahdi Zhandi Associate Professor, Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran 0000-0003-2886-9747 Armin Towhidi Professor, Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran 0000-0002-3288-1709 Mojtaba Zaghari Professor, Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran 0000-0003-4440-3584 Mahdi Ansari Ph. D. Candidate, Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran 0000-0001-8481-8667 Journal Article 2017 04 22 The current study was carried out to evaluate the effect of Letrozole feeding on plasma LH and FSH concentrations and testicular histology in Ross 308 broiler breeder roosters. Twenty 40-week old roosters were randomly divided into four groups, individually housed and fed different levels of capsulated Letrozole including 0 (L0), 0.5 (L0.5), 1 (L1) or 1.5 (L1.5) mg/bird/day for 12 consecutive weeks. Blood sampling was done on 1^th, 3^th, 5^th, 7^th and 9^th weeks of trail. Testicular histology was assessed on samples from last week (12^th) of experiment. According to the results, plasma LH and FSH levels, seminiferous tubule diameter and epithelium thickness as well as Leydig cell numbers were significantly increased in Letrozole treated groups compered to control group. The highest concentration of FSH and LH were recorded for L1 (10.39 ±0.11 and 2.93±0.08) and L1.5 (9.5±0.2 and 3.17±0.08) groups, respectively. Both L0.5 and L1 groups had significantly higher spermatogonial numbers than control group. However, blood vessel numbers were not significantly affected. In conclusion, orally feeding Letrozole (1 and 1.5 mg) could improve gonadotropin concentration and testicular histology parameters of male broiler breeders at 40 weeks of age. Further studied are needed to confirm these results and extend them to final fertility. The current study was carried out to evaluate the effect of Letrozole feeding on plasma LH and FSH concentrations and testicular histology in Ross 308 broiler breeder roosters. Twenty 40-week old roosters were randomly divided into four groups, individually housed and fed different levels of capsulated Letrozole including 0 (L0), 0.5 (L0.5), 1 (L1) or 1.5 (L1.5) mg/bird/day for 12 consecutive weeks. Blood sampling was done on 1^th, 3^th, 5^th, 7^th and 9^th weeks of trail. Testicular histology was assessed on samples from last week (12^th) of experiment. According to the results, plasma LH and FSH levels, seminiferous tubule diameter and epithelium thickness as well as Leydig cell numbers were significantly increased in Letrozole treated groups compered to control group. The highest concentration of FSH and LH were recorded for L1 (10.39 ±0.11 and 2.93±0.08) and L1.5 (9.5±0.2 and 3.17±0.08) groups, respectively. Both L0.5 and L1 groups had significantly higher spermatogonial numbers than control group. However, blood vessel numbers were not significantly affected. In conclusion, orally feeding Letrozole (1 and 1.5 mg) could improve gonadotropin concentration and testicular histology parameters of male broiler breeders at 40 weeks of age. Further studied are needed to confirm these results and extend them to final fertility. https://ijas.ut.ac.ir/article_63031_5ccd2108f3dda96857ab49345146e0ca.pdf