Modifying Diets for Heat-Stressed Dairy Cows
Maintaining effective fiber intake:Adequate effective fiber is necessary for maintaining rumination, buffering the rumen contents, and efficiently digesting forages and grain components of the diet. Heat stress increases the rate of respiration and panting, decreaser rumination time, and results in a decrease in the amount of saliva and bicarbonate in the blood. These changes result in a decreased buffering of the rumen and blood. Thus, decreasing the fiber content and increasing the amount of starch in a diet is the last change you want to make in an attempt to increase the energy of the diet because ruminal acidosis could result. However, feeding excessive amounts of neutral detergent fiber (NDF) to dairy cows under heat stress is detrimental. High NDF forages are generally lower in forage quality and result in more heat of fermentation when digested in the rumen , and thus the dairy cow needs to dissipate more heat compared to consuming diets with adequate amounts of fiber.