Gonadal sperm reserve in purebred Landrace and Large White boars of high average daily gain

The present study investigated the effects of average growth rate (AGR) levels and age on the number of sperm cells per gram of testis parenchyma and on the gonadal reserve in Landrace (LD) and Large White (LW) boars. In Experiment 1, the effects of breed (LD, LW), level of AGR from birth up to 90 days of age (Level 1: 384 +/- 32 g/day; Level 2: 512 +/- 22 g/day; Level 3: 624 +/- 41 g/day), and age (13, 15, 17, 19 and 21 weeks) on testicular cell concentration were evaluated. Data were analyzed under a 2 x 3 x 4 factorial design. There were significant effects associated with breed (P < 0.001) and age (P < 0.001) but not with AGR (P > 0.05) on sperm cell number per gram of testicular parenchyma. The number of cells increased with age and was greater in LW than in LD young boars, mainly those up to 19 weeks of age. In Experiment 2, the effect of two AGR levels (Level 1: 649-694 g/day; Level 2: 813-885 g/day) from birth up to 100 kg body weight on the number of sperm cells per gram of testis parenchyma and on the gonadal reserve was investigated using 59 purebred LD and LW boars. The boars were castrated at 23, 25, 29 and 33 weeks of age. Age of boars significantly affected gonadal sperm reserve and the number of sperm cells per gram of testicular tissue (P < 0.001). Breed of boars and AGR Levels did not significantly affect number of sperm cells and gonadal sperm reserve (P > 0.05). It was concluded that the number of sperm cells in the testicular tissue of young boars is influenced by their breed and age, but not by the level of their AGR.