Remember that a cow's energy requirement for lactation is unchanged and her energy needs to remain cool actually increase. Therefore, maintaining adequate nutrient intake becomes critical to avoid undue milk production loss. 0.73 0.83 Optional methods to increase dietary nutrient density include feeding high quality forage, feeding more grain and using supplemental fats. Total dietary fat should not exceed 7 percent. The inclusion of a buffer to the ration often can help alleviate some of the milk fat depression and maintain feed intake.
Minerals are also more easily depleted during hot summer months.
The increase in respiration and perspiration will cause an excessive loss of water, thereby reducing mineral levels. Potassium can be increased to 1.3 to 1.5 percent of the total dietary dry matter, sodium to 0.5 percent, and magnesium levels increased to 0.3 percent. If less forage is consumed, and the forage is high in quality, the cow's rumination activity may decrease. Consequently, the proper use of buffers becomes important to maintain intake, ruminal pH, and milk production. The producer's primary feeding goal should be to maintain intake and limit the negative effect of heat stress on milk production.