Effects of Higher Dietary Cation with or without Protected Fat and Niacin on the Milk Yield and Thermoregulatory Ability in Holsteins During Summer Heat Stress

摘要

Heat stress is one of the major factors that decrease milk production and fertility of dairy animals during summer. Thermal environment and the metabolic heat production are two sources of heat which can negatively affect milk production of dairycows (Linn, 1997). For normal behavior, physiological metabolism and milk yield, it is essential that the body temperature of cows should be maintained within narrow limits.