Correlation of broiler breeder male semen production and testes morphology

Broiler breeder males were fed either a 9, 12, or 15% protein diet (2,819 kcal/kg metabolizable energy) from 6 to 50 wk of age. From 48 through 49 wk of age semen volume (VOL) and concentration (CONC) and number of spermatozoa per ejaculate (NSE) were determined, and at 50 wk of age body weight (BWT) and testes weight (TWT) were measured. Spermatogenic activity was evaluated histologically by a) a computer-aided assessment of seminiferous epithelial area (SEA), tubular diameter (TD), and epithelial height (EH); and b) visual appraisal of seminiferous tubular size and maturity of cell types (testes score-TS). Relationships among NSE, TS, SEA, TD, EH, BWT, and TWT were determined. Dietary protein had no significant effect on VOL, CONC, NSE, BWT, TWT, TS, SEA, EH, or TD. Significant positive correlation coefficients were observed among NSE, TS, SEA, TD, and EH, indicating moderate effectiveness of these methods in evaluating reproductive state. Low correlations between NSE and other variables may have resulted from 25% of the males having high TS but failing to ejaculate semen. Body weight and TWT, as well as BWT and NSE, were positively correlated. The SEA and TD had higher correlations with TWT than with BWT.