Castrillejo A, Moraña A, Bielli A, Gastel T, Molina J R, Forsberg M, Rodriguez-Martinez H
Department of Obstetrics and Gynaecology, Faculty of Veterinary Medicine, Uppsala, Sweden.
Acta Vet Scand. 1995;36(2):161-73. doi: 10.1186/BF03547686.
The present study was undertaken to estimate the time for the attainment of spermatogenesis in springborn Corriedale ram lambs under conditions of extensive grazing systems in Uruguay. Clinical (live weight, scrotal circumference, penile/preputial separation), morphological (light and electron microscopy) and endocrinological (testosterone levels) parameters were examined. Two experiments in 2 consecutive years were carried out. In Exp. I, 40 ram lambs were clinically examined, weighed, and blood-sampled at 2 week-intervals between 78 and 216 days of age. Sixteen were castrated in 3 selected periods: 132-162 (n:2), 145-175 (n:6) and 186-216 days (n:8). In Exp. II, 40 ram lambs appertaining to the next generation of the same flock were examined as above at 180-210 days of age, and castrated for morphological studies. The time for attainment of complete spermatogenesis correlated significantly with most corporal parameters (i.e. scrotal circumference (r = 0.52); testicular weight (r = 0.61), epididymal weight (r = 0.60), penile/preputial separation (r = 0.75). The age of castrated ram lambs correlated with the degree of spermatogenesis (r = 0.83), although no significant correlations were found with live weight or with levels of circulating testosterone. The histology showed major variations in the degree of development of the seminiferous epithelium. Cells undergoing degeneration were a common finding through the initial stages of spermatogenesis, coincident to the presence of sperm abnormalities and foreign cells in semen. By day 180 and onwards, both histology and seminal picture normalized. It is concluded that, under these rearing conditions, the onset of puberty (expressed as morphologically established spermatogenesis) in Corriedale ram lambs is attained at 180-216 days of age when they reach 23 cm of scrotal circumference and 191 g of testis weight. The finding of a high correlation between these parameters (r: 0.93) confirms the usefulness of the measurement of scrotal circumference during clinical examination of ram lambs in this breed.
本研究旨在评估乌拉圭粗放放牧系统条件下，春季出生的考力代公羊羔羊达到精子发生的时间。对临床参数（体重、阴囊周长、阴茎/包皮分离情况）、形态学参数（光镜和电镜观察）以及内分泌参数（睾酮水平）进行了检测。连续两年进行了两项实验。在实验I中，40只公羊羔羊在78至216日龄期间每隔2周进行一次临床检查、称重和采血。在3个选定时期对16只羔羊进行了去势：132 - 162日龄（n = 2）、145 - 175日龄（n = 6）和186 - 216日龄（n = 8）。在实验II中，对同一羊群下一代的40只公羊羔羊在180 - 210日龄时进行上述检查，并进行去势以进行形态学研究。达到完全精子发生的时间与大多数身体参数显著相关（即阴囊周长（r = 0.52）；睾丸重量（r = 0.61）、附睾重量（r = 0.60）、阴茎/包皮分离情况（r = 0.75））。去势公羊羔羊的年龄与精子发生程度相关（r = 0.83），尽管未发现与体重或循环睾酮水平有显著相关性。组织学检查显示生精上皮发育程度存在较大差异。在精子发生的初始阶段，常见到正在退化的细胞，同时精液中存在精子异常和外来细胞。到180日龄及以后，组织学和精液情况均恢复正常。结论是，在这些饲养条件下，考力代公羊羔羊在180 - 216日龄、阴囊周长达到23厘米且睾丸重量达到191克时进入青春期（以形态学上确立的精子发生来表示）。这些参数之间的高度相关性（r：0.93）证实了在该品种公羊羔羊临床检查期间测量阴囊周长的实用性。
