Significance of metabolic response in livestock for adapting to heat stress challenges

Abstract

The animals possess various inherent mechanisms to cope up with the changing environmental conditions. It has been observed that the ability of the animals to adjust with these climatic extremes is related to their level of adaptation and this is inversely correlated with their production potential. In depth understanding of metabolic response of livestock adaptation might pave way for developing more viable adaptive measures to cope up livestock production system to climate change. Hence, this review is an attempt to cover the significance of metabolic response to animal adaptation during heat stress. In animals, less feed intake helps to reduce the internal heat production by minimizing the metabolic processes to adapt the heat stressed condition. Thyroid glands and thyroid hormones are mainly known to have a very important role in the thermoregulation and homeostasis of energy and protein metabolism. Further, the histological sections of the thyroid gland of livestock subjected to heat stress indicates pathological changes of less thyroglobulin in the thyroid cells reflecting a significant decrease in thyroid activity. Changes in the concentration of thyroid hormones in the blood reflect the metabolic and nutrient status of the body. Thyroid hormones play a critical role in thermogenesis and therefore are an important reflection of adaptation to heat stress in livestock species. The roles of metabolic regulators are crucial in assessing the physiological response to heat stress through various enzymes governing the metabolic reactions in blood. The decreased level of non-estrified fatty acid (NEFA) during heat stress condition in livestock is attributed to enhance the glucose burning as a presumable strategy to reduce metabolic heat production in the animal body. In addition, alteration in the levels of both aspartate aminotranspharase (AST) and alanine aminotranspharase (ALT) are correlated to adaptive potential of livestock to environmental challenges. Based on this review, it was concluded that metabolic response is one of the primary means by which the animals tries to cope up with heat stress challenges. The animal reduces their metabolic activities in an effort to reduce the metabolic heat production to cope up with outside environment heat stress condition.