At present no single parameter can predict potential daily sperm production (DSP) in bulls. Sertoli cells (SC) are responsible for nourishing and providing physical support to germ cells (GC) throughout spermatogenesis. The size of the SC population established before puberty is one of the major factors determining DSP in the bull. Fine needle aspiration (FNA) is a technique used for diagnostic purposes in many species but its application to determine the size of the SC population remains unexplored. Our objectives were to compare two stains (immunohistochemistry vs. conventional HE) and three techniques to determine SC density in neonatal and prepubertal bulls [22G FNA (SMEAR), 14G needle with vacuum (CORE) and tissue section (HIS)], and the effects of three different interventions on testicular growth, development and cytology in neonates, pre and peripubertal bulls: corn supplementation during mid to late gestation of dams, the age of the dam and the administration of vitamin A. The significant correlation observed between GC and SC counts in neonatal and prepubertal bulls, highlighted the relationship between both cell populations established in the early gonad. Although no significant correlation existed between techniques for SC density, the significant relationship established between SC counts and GATA4+ cell density implies the process can be automated. Corn supplementation to multiparous dams during mid to late gestation did not have any effect on testicular gross parameters and cytology in neonatal bulls coincident with the lack of differences in fetal growth between treatments. No significant differences in scrotal circumference, testicular weight or cytology existed between prepubertal bulls from primiparous heifers or adult multiparous cows. Nevertheless, bulls from heifers had lower bodyweights at 194 days of age compared with bulls from cows. The administration of vitamin A to peripubertal bulls had no effect on scrotal circumference, testicular weight or cytology. Nevertheless, epididymis in treated bulls were significantly heavier than non-treated animals. The data generated in the present experiments highlights the need for more research to generate new interventions aiming to influence the size of the SC population in the testis and the potential daily sperm production in the beef bull.