ENVIRONMENTAL AND STRESS MANAGEMENT

Environmental management and stress management play a crucial role in supporting cattle reproduction, particularly in preventing delayed ovulation [187]. Environmental stressors, including high temperature, humidity, poor ventilation, and overcrowding, can induce heat stress, which disrupts hormonal balance and ovarian function [188, 189]. Heat stress stimulates cortisol secretion via the HPA axis, suppressing GnRH pulsatility and reducing LH surge amplitude, thereby delaying follicular maturation and increasing the risk of persistent follicles [190]. Additionally, heat stress decreases granulosa cell steroidogenic enzyme activity, resulting in lower estradiol production and less pronounced estrus behavior [191].

Practical animal-based indicators of environmental stress include increased respiration rate, elevated rectal temperature, reduced lying time, altered locomotion, and excessive BCS loss during early lactation. These measures correlate with impaired follicular development, delayed or absent LH surges, and higher incidence of delayed ovulation, providing actionable field-level parameters for reproductive risk monitoring [192].

Effective environmental and welfare management strategies include optimizing housing conditions, ensuring adequate ventilation, providing cooling systems (fans, sprinklers, or integrated shade + forced ventilation + evaporative cooling), and managing stocking density [193]. Among these, integrated cooling systems offer the most effective heat abatement, followed by forced ventilation alone, while shade-only or natural airflow systems are less protective under high heat load conditions. Additional measures such as proper lighting, cleanliness, and comfortable lying areas support physiological and behavioral balance, helping maintain GnRH–LH axis activity and timely ovulation [194, 195].