PSX-1 Effects of maternal stressors on testicular development in utero in beef cattle.

Abstract Maternal stressors during pregnancy, particularly nutritional restriction, may impair fetal testicular development in beef cattle, with implications for bull fertility and herd productivity. This study evaluated the effects of mild mid-gestational protein restriction on in utero testicular development by assigning 32 Angus cows to two dietary treatments: Non-supplemented (7% crude protein, 80% of requirements) or Supplemented (10% crude protein, 100% of requirements). Bull calves (n = 19) were castrated at 2–3 months of age and testes were subjected to histology (seminiferous tubule diameter and lumen development) and immunohistochemistry (Sertoli cell and spermatogonia markers). In addition, serum anti-Müllerian hormone (AMH) concentrations were determined. There were no differences (P > 0.05) between groups in testicular volume, tubule diameter, or AMH concentrations (P > 0.25). However, interstitial tissue composition tended to differ (P = 0.065), with NS calves having modest reductions, suggesting subtle deficits in somatic and germ cell proliferation under maternal nutritional stress. Calf birth, weaning and castration weights were unaffected (P > 0.12). Although mild mid-gestational protein restriction did not overtly disrupt early testicular architecture, marginal interstitial tissue changes suggest potential subtle effects of maternal nutrition on fetal testicular development that may not manifest until later stages of growth or reproductive maturity. Long-term studies assessing puberty onset and semen quality in progeny are critical to clarify these developmental impacts.