Cold temperatures, wind chill, snow, freezing rain, and mud are all terms that come up at some point in describing our winter weather here in Ohio. The cattleman needs to pay attention to the terms because they play a role in determining the nutrient requirement of cattle. Specifically these conditions increase the energy requirement of cattle, can reduce the efficiency of utilization of dietary energy, can decrease voluntary intake, and can change cattle behavior.
As temperature falls below a critical level, the cow must increase energy intake to maintain body temperature and basic body maintenance functions. Cattle have a comfort zone of 59 to 77 degrees F that is considered optimum for body maintenance, animal performance and health. At temperatures lower than the comfort zone, that is, below 59 degrees F, the animal can make use of a thickening hair coat and heat from normal tissue metabolism and rumen fermentation to conserve body heat without any increase in energy intake requirements. This is known as the thermoneutral zone. The lower boundary of this zone is referred to as the lower critical temperature (LCT). Below the LCT, animal metabolism must increase to provide adequate heat to maintain body temperature. This can be accomplished through increased energy intake. The general rule of thumb is that energy intake must increase by 1% for each degree of cold below the LCT.
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