Effects of environment and management on mammary development in dairy animals

The structural development of the mammary gland is the primary physiological determinant of lifetime lactational capacity in dairy species. This review synthesizes current knowledge of extrinsic modulation of mammary development, emphasizing the critical role of mammary stem cells (MaSCs) in driving glandular plasticity during embryonic, prepubertal, and dry periods. Environmental stressors, such as heat stress during late gestation, compromise alveolar proliferation to the dam and induce transgenerational epigenetic modifications that suppress future productivity to the offsprings. Conversely, management interventions such as accelerated pre-weaning nutrition, stage-specific photoperiod modulation, and increased milking frequency are shown to positively program the MaSC niche, enhancing epithelial cell expansion and lactation. Furthermore, this review contrasts established bovine models with the dromedary camel, highlighting unique anatomical architecture, oxytocin-dependent alveolar storage, and evolutionary resilience to hot climatic conditions. We conclude that maximizing dairy efficiency requires shifting from reactive management to proactive strategies that improve management of rearing environment and leverage the mammary epithelia proliferative potential.