Madani M O, Rahal M S, Zawia M T, Eluwhaishi B A
Br Vet J. 1989 May-Jun;145(3):276-88. doi: 10.1016/0007-1935(89)90080-8.
Puberty and early sexual development were studied in 143 Libyan fat-tailed ram lambs, equally representing Brownhead and Blackhead strains of this breed. The two strains did not differ in any of the measured parameters in a consistent way, yet the Brownhead lambs tended to be slightly heavier and to have a slightly larger testis diameter than Blackheads. At the commencement of the observations when the lambs were 69 days old, 25.2% had fully descended testes at a significantly higher (P less than 0.01) mean (SD) body weight (24.1 +/- 4.1 kg) than those with partly descended (69.2%, 15.7 +/- 6.3 kg) or with non-descended testes (5.6%, 19.5 +/- 3.2 kg). Testes development followed a triphasic pattern with an initial and a final phase of slow growth and a middle phase of fast growth, commencing at a weight of 24.5 kg and an age of 85 days and lasting until the weight of 36-43 kg and age of 180-200 days in both strains. The separation of penile adhesions commenced at a mean body weight and age of 33.6 +/- 3.7 kg and 125.5 +/- 27.4 days respectively and was completed at a mean weight and age of 38.3 +/- 4.2 kg and 153.4 +/- 29.9 days. Only four lambs failed to show complete penile separation. Age had little influence on testis descent or on penile development. Puberty was assessed in 71 lambs using sperm recovery following electroejaculation as an end point. Most of these lambs (92.9%) reached puberty at a mean (SD) age of 171.5 (39.9) days, mean body weight of 39.9 (9.3) kg, mean testis diameter of 4.1 (0.4) cm and mean horn length of 21.4 (3.7) cm. Puberal lambs were significantly superior to non-puberal lambs (P less than 0.01) in all these counts except for age which was similar in both categories. Direct testicular observation showed a strong correlation between testis diameter, testis weight, body weight, sperm concentration/g testis weight and to testis histology. Age was poorly correlated to testis weight, histology or sperm concentration. It is concluded that the body weight is a major determinant of puberty in this breed. It is also considered that the two strains of the breed are remarkably similar in the studied aspects of puberty and sexual development.
对143只利比亚肥尾公羊羔羊进行了青春期和早期性发育研究，这些羔羊平均代表了该品种的棕头和黑头品系。两个品系在任何测量参数上均未表现出一致的差异，但棕头羔羊往往比黑头羔羊稍重，睾丸直径也稍大。在观察开始时，羔羊69日龄，25.2%的羔羊睾丸完全下降，其平均（标准差）体重（24.1±4.1千克）显著高于部分下降（69.2%，15.7±6.3千克）或未下降（5.6%，19.5±3.2千克）的羔羊（P<0.01）。睾丸发育呈三阶段模式，最初和最后阶段生长缓慢，中间阶段生长迅速，两个品系均始于体重24.5千克、年龄85天，持续至体重36 - 43千克、年龄180 - 200天。阴茎粘连分离分别始于平均体重33.6±3.7千克、平均年龄125.5±27.4天，完成于平均体重38.3±4.2千克、平均年龄153.4±29.9天。只有4只羔羊未出现完全的阴茎分离。年龄对睾丸下降或阴茎发育影响不大。对71只羔羊以电刺激采精后精子回收作为终点来评估青春期。这些羔羊中的大多数（92.9%）在平均（标准差）年龄171.5（39.9）天、平均体重39.9（9.3）千克、平均睾丸直径4.1（0.4）厘米和平均角长21.4（3.7）厘米时达到青春期。在所有这些指标上，青春期羔羊均显著优于未青春期羔羊（P<0.01），但年龄在两类羔羊中相似。直接观察睾丸发现，睾丸直径、睾丸重量、体重、每克睾丸组织精子浓度与睾丸组织学之间存在很强的相关性。年龄与睾丸重量、组织学或精子浓度的相关性较差。结论是体重是该品种青春期的主要决定因素。还认为该品种的两个品系在青春期和性发育的研究方面非常相似。
