Testicular development and body weight gain from birth to 1 year of age of Awassi and Redkaraman sheep and their reciprocal crosses

An experiment was conducted to compare testicular volume (TV), scrotal circumference (SC) and body weight (BW) gain of 10 Awassi (A), 10 Redkaraman (R) ram lambs with those of their reciprocal crosses: R × A (10 ram lambs) and A × R (10 ram lambs). Measurements were taken at birth, 90 (weaning), 180, 270 and 360 days of age. TV was similar in the purebred and crossbred lambs, while genotype effect was found significant (P < 0.05) for BW at birth, weaning and 180 days of age and SC at 270 days of age. In general, A lambs had lower BW than the other breeds of lambs. Highest estimates of heterosis were 20% and 12.3% in TV and SC, respectively, at 9 months of age, Redkaraman × Awassi lambs had larger SC than Awassi lambs. Age at puberty as determined by inflection point in SC growth was earliest in R × A (119 days) lambs, followed by A × R (139 days), R (140 days), whereas A lambs were the oldest to reach puberty (152 days).