Environmental Stress and Feed Intake in Chickens: Neuroendocrine Mechanisms and Mitigation Strategies

Environmental stresses negatively affect feed intake in chickens, leading to reduced growth rates and significant economic losses. This review examined the molecular mechanisms of stress-induced loss of appetite, focusing on the hypothalamic regulation of appetite-associated neuropeptides, the role of the HPA axis, elevated CORT levels, and stress-induced inflammatory cytokines that inhibit appetite-stimulating signals. Current mitigation strategies, such as cooling systems, nutritional supplements, early-life programs and genetic selection using QTL mapping, have been shown to provide varying levels of effectiveness. Limited understanding of how multiple stressors act in concert at the cellular level in natural environments is a major limitation. Furthermore, the majority of studies focus on acute stress, while low-grade chronic stress models are underrepresented despite their commercial importance. A significant shortcoming is the absence of validated non-invasive biomarkers to predict stress-induced feed reductions before production losses begin. This review examines the molecular neuroendocrine mechanisms of stress-induced anorexia and the available mitigation strategies, highlighting the disconnect between mechanistic understanding and current interventions, and emphasizing the need for mechanism-based proactive measures to sustainably improve feed intake and productivity in stressed chickens. Therefore, future research should focus on integrated multi-stress frameworks and the evaluation of the lasting epigenetic effects of early-life interventions in chickens.