Recent Advances in Nutritional Requirements and Metabolic Homeostasis Regulation of Animals Under Stress Conditions.

Animal stress is a complex physiological state characterized by a suite of non-specific responses (e.g., lethargy, anorexia, and impaired growth) to various internal or external threats, collectively known as stressors. It is the synthesis of non-specific responses produced by the body to various external or internal stimuli. Animals in livestock production are often stressed by breeding density, inappropriate temperature and humidity, harmful gases, noise and complicated immunization. Consequently, the nutritional requirements and underlying metabolic mechanisms in stressed animals are critical and growing research hotspots. Emerging evidence has shown that nutritional intervention can maintain animal health and performance under stresses. In addition, the regulation of metabolic pathways and targets under different stress states is also a potential way to alleviate the stress response of animals. With the rapid development of intensive farming and the aggravation of environmental changes, animals are facing increasing challenges such as heat stress, transportation stress, and pathogen infection. The resulting metabolic disorders and health problems seriously restrict the production efficiency of animals. This review aims to systematically analyze the variation in animal nutritional requirements under stress, clarify the molecular mechanism of metabolic imbalance, and summarize the regulatory targets and effects of nutritional intervention strategies, providing theoretical basis and technical support for solving stress-related problems in livestock production.