Heat Stress in Cattle

Posted on May 6, 2014

Heat Stress in Cattle

With summer approaching it is time to start thinking about heat stress and the effects it has on cattle. It is easier to quickly assess the effects of heat stress in dairy as milk production drops occur very rapidly with the onset of the first heat wave. What is heat stress? The comfort zone for cattle of Bos Taurus (English and European breeds) is 39 degrees F up to about 75 degrees F. THI or the temperature humidity index is of greater significance than temperature alone. High temperature along with high humidity lessens evaporation cooling. Cattle rely mainly on respiration to cool themselves. They have a poor sweating mechanism so this is an ineffective cooling mechanism in cattle. Heat from fermentation of feeds in the rumen also adds to the heat load. Coping mechanisms for heat stress are to reduce activity during the heat of the day and consume less feed. Blood flow is restricted to the digestive tract, reproductive tract and the extremities and shunted to the vital organs (heart, lungs, liver) in an attempt at reducing core body temperature. Cellular metabolism is disturbed and some of the cell membranes shut down in an attempt to keep core body temperature from rising. As a result of the physiological changes there is a loss of electrolytes (sodium, potassium and bicarbonate). Cows capable of producing more milk are greater risk than lower producing cows. Some effects of heat stress are: Refusal to lie down, Open mouth panting, Reduced feed intake with marked reduction in milk flow (25 to 50%), Greater incidence of metabolic disorders, Impaired immune function, Lower milk fat and milk protein, Reduction in estrus activity (few cows observed in standing heat)

To lessen the burden of heat stress Whitestone Feeds has introduced a heat stabilizer pack, named HS-10, that will enhance the cow’s ability to cool her by improving blood flow to the digestive system and extremities, and naturally occurring plant extracts to aid in the digestive process. In addition HS-10 also includes some enzymes to aid in the fermentation process. Results of one of the key ingredients were thoroughly researched in an Israeli trial. Copy of the trial is available upon request. For more information about the exciting new HS-10 heat stabilizer product, please use the Contact Us page to let us know how to reach you.