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Heat Stress and Mycotoxins: A Profit-robbing Combination

Larry Roth, Ph.D., PAS - Vice President of Nutrition, Agrarian Solutions and Caroline Knoblock, MSc, - Director of Nutrition

Heat stress and mycotoxin contamination are harmful enough alone, and especially so when experienced together by dairy cattle. Heat stress occurs when cows cannot dissipate the heat they produce and try to compensate physiologically in ways that result in less milk and poorer reproduction. Why does this happen?

Heat stress results in a cascade of events whereby cows attempt to alleviate internally produced heat via increased respiration; however, there are also consequences including reduced feed intake, lowered nutrient intake, altering of digestive pH, increased digestive pathogen levels and leaky gut syndrome. The immune system attempts to defend an animal during a nutrient restricted time, and nutrients are re-partitioned from productive purposes (growth, milk production and reproduction) to simply keeping the animal alive.

Consuming a mycotoxin-contaminated diet compounds the negative heat stress effects as another inflammation-source to which the cows must respond, and once again diverting nutrients from profitable utilization.

How do we protect our cows from this deadly duo? Cooling systems involving air movement and moisture for evaporative cooling are essential during heat stress periods. It is also critical to feed palatable diets with additions to restrict wild yeast and mold growth from metabolizing nutrients in the TMR as well as creating internal issues.

Dairy producers and nutritionists also cite supplementing Select DTX™ Concentrate as a profitable practice when feeding a mycotoxin-contaminated diet during heat stress periods. Independent research indicated that DTX feeding may protect cows from harmful mycotoxin effects and with the reduced inflammation enable nutrients to be re-partitioned to profitable uses.