ahmad zare shahne

The role of thyroid hormones has been recognized in normal embryo development many years ago. These hormones also affected the development of reproductive organs and their activity. This study was conducted to investigate the effect of inducing hypothyroidism by propyl-2-thiouracyl (PTU) on lambs testicular histomorpho-logy and plasma testosterone concentration. Eighteen Lori-Bakhtari male lambs were divided to 3 groups (n=6) and each received one of the treatments as Control (C: 0 mg PTU/kg BW), Low (L: 10 mg PTU/kg BW) and High (H: 20 mg PTU/kg BW) by gavages, during a 60d experimental period. At the end of the trial, lambs were slaughtered and testes were removed to evaluate their histomorphological characteristics. Mean concentration of T4 and T3 decreased significantly in L and H groups compared with C group (p<0.05). Hyphothyroidism increased testis weight, number of sertoli and lydig cells, diameter of Seminiferous tubules, diameter of seminiferous lumen, total spermatogonia, number of primary spermatocyte, and total spermatids (p<0.05). However, PTU had no significant effect on plasma concentration of testosterone (p>0.05). In the present study, PTU increased testicular weight and the number of cells involved in sperm and testosterone production. Sheep breeders may consider hypothyroidism as a potential approach to increase sperm production capacity in rams before puberty. However, further investigation should be carried out on the quality and quantity of ram's sperm.

The present research was conducted to estimate the dietary lysine (Lys) requirements of growing quails as based on performance and carcass constituents parameters at 3 to 24 d of age. The experiment was carried out in a complete randomized design arrangement the 6 dietary Lys levels; 1, 1.15, 1.30 (NRC 1994), 1.45, 1.60, and 1.75 %, from 3 to 24 d of age. A dose-response diet mainly based on corn, corn gluten and soybean meal was used. Lys content was minimized in dose-response diet (1%) while assuring the minimum levels of all other essential amino acids in a manner that would meet or exceed NRC (1994) recommendation. Each treatment consisted of 5 floor pens as replicate with 50 quail chicks. Second order equation methods were utilized for determining the optimum dietary Lys levels. With increase in dietary Lys, body weight, body weight gain and feed conversion ratio improved significantly (P < 0.05). In female Japanese quail, carcass and breast weights were significantly (P < 0.05) affected by dietary Lys. While dietary Lys has no significant effect on thigh weight, carcass and breast yields in female quails (P > 0.05), in male quails, Carcass, breast, thigh weights as well as yields are significantly affected by Lys level, during the birds 3-24 d of age (P < 0.05). Lys needs based on second order equation method when mixed performance parameters taken as response of Lys requirement were recorded as 1.48% at 3-24 d of age. The data suggested that total Lys requirement could be estimated based on second order equation method as 1.48, 1.54% respectively for female and male quails when carcass constitutents are considered at the birds 24 d of age. These results indicate that the NRC (1994) Lys requirement of Lys 1.30% (total basis) is not adequate from the birds 3 to 24 d of age for optimum performance in the case of Japanese quails.