Abstract
This experiment was designed to study the relationship between growth rate and sexual development in Najdi ram lambs. Forty-five Najdi ram lambs were used in nine age groups (1–9th month age), keeping 5 lambs in each group. Results show that mean testis size and scrotal circumference increased at a constant rate, reaching a maximum value of 392.00±2.00g and 25.00±0.32cm respectively, at the age of 9months. A similar trend of growth was observed for the mean body weight, reaching a maximum value of 40.2±0.20kg at the age of 9months. There was a positive correlation between the increasing rates of body weight and size of the testis. There were significant differences (P<0.05) in testis size, scrotal circumference and body weight of lambs between all ages (1–9months). The histological section of testis showed that a small number of mature sperms appeared in the eighth month of age and their numbers increased in the ninth month. In conclusion, the current findings indicated that puberty in Najdi rams occurs between the 8th and 9th months of age.