Spermatogenic activities of the left and right testes of hemicastrated and intact cockerels

One hundred cockerels of the Hacco strain were reared in deep litter. At 5 weeks of age the left testes of 30 cockerels and right testes of another 30 cockerels were surgically removed. The remaining cockerels were sham operated. At 10, 15, 20 and 25 weeks of age equal numbers from each group were killed. The rate of testis growth, the spermatid/spermatozoa reserve for each genital tract, and the relative spermatogenic activity (i.e., spermatid/sperm per g of testicular tissue) were determined for the left and right testes at the different ages.At 10 weeks of age only spermatids were found in all the testes, with concomitant very low relative spermatogenic activities. The weights of the testes increased with age and compensatory hypertrophy occurred in the testes of the hemicastrates from 15 weeks of age. The mean of the sperm reserve of the left (7.391 × 10⁹ sperm) and right (8.66 × 10⁹ sperm) genital tracts of hemicastrates contained significantly more (P < 0.05) sperm than the sum of the means of the sperm reserves in the left and right genital tracts (5.19 × 10⁹sperm) of the intact cockerels at 25 weeks of age.The relative spermatogenic activities varied with age but the pattern was similar for all cockerels, with the activities of the testes of the hemicastrates being significantly higher (P < 0.5). In all cases the values for the right testes were higher than those for the corresponding left testes.At 15 weeks of age both spermatids and spermatozoa were found in 71.4% and 100% of the right and left testes of the hemicastrates, respectively, and in 25% of the left testes of the intact cockerels. Only spermatids were found in the right testes of the intact cockerels.Hemicastration caused the right testes of the hemicastrates to produce sperm earlier than those of intact cockerels. The left testes in all cases produced sperm earlier than the corresponding right testes. Hemicastration enhanced sperm numbers per g testes (i.e., relative spermatogenic activity).