Management of Dairy Animals for Improved Health and Production during Circadian Pattern: A Review

A circadian rhythm is a roughly 24-hour cycle in the biochemical, physiological, or behavioral processes of living entities, The term "circadian" comes from the Latin circa, "around", and diem or dies, "day", meaning literally "approximately one day.” The nature of the rhythms is endogenous and innate and driven by an endogenous clock. Such self sustained oscillations with a period of about one day are called “circadian rhythms” A variety of biological variables including behavior, physiological function and biochemical factor oscillate in organisms. Rhythmicity in physiological parameters is an important process both as convenient and reliable markers of operation of the biological clock and as an indicator of general health of an animal. One of the most dramatic features of the world in which we live is the cycle of day and night. Correspondingly, almost all the species exhibit daily changes in their behavior and or physiology. These daily rhythms are not simply a response to the 24-hour changes. Thermal environment exert a profound influence on various physiological responses and ultimately the productivity of animals. Excessive hot exposure affects the animals at cellular level and is reflected in production and accumulation of the damaging molecules i.e. free radicals. In this part of review, pertinent information on the effect of circadian variations on physiological responses, oxygen consumption, heat production, and heat loss by dairy animals has been emphasized.