It seems like the weather has been nothing but cold since thanksgiving. Unfortunately, that trend is only projected to continue. That means it is important to feed beef cattle to protect them from the harsh elements. Cold stress occurs when the environmental temperature is below the animals lower critical temperature.The lower critical temperature is reached when the animal can no longer maintain their internal body temperature through behavioral modifications such as seeking shelter or grouping together.
There are several factors that determine an animals lower critical temperature: air temperature and wind chill, acclimation, body condition and metabolic rate. The effects of air temperature and wind chill on the animal are cumulative with high wind speeds making it difficult for the animal to stay warm. The lower critical temperature of beef cattle that have not acclimated to cold weather by developing a thick winter coat is at or below freezing. Once cattle have developed a winter coat, the lower critical temperature moves to around 18°F. Body condition also moves the lower critical temperature, with fatter cattle being able to withstand colder temperatures and wind chill. Finally, the animal’s natural reaction to being cold is to increase metabolic rate. Those that naturally have a higher metabolic rate tolerate lower temperatures better.
The demand to increase metabolic rate to stay warm also increases the cow’s nutrient requirements. The energy requirement of cold stressed cattle increases significantly. If the cow is fed a high quality diet, dry matter intake will increase to the extent that their gut capacity allows, and the cow will maintain body condition and continue to perform well. If however, cattle are fed poor quality forages with little or no energy supplementation, feed intake will decrease, animals will lose weight thereby decreasing body condition score and perform poorly.
Under cold stress conditions it is important that producers supplement high energy feeds, provide quality forages and monitor cattle for weight loss. Producers can send forage and supplement samples to Ward Laboratories, Inc. to determine the best diet to provide cattle during winter weather conditions. When feeding diets high in rapidly digestible carbohydrates from energy supplements and high quality forages, it is important to feed daily to avoid acidosis issues.
Additionally, feeding in the late afternoon or evening is prefered to align the height of metabolic heat production with the nightly low temperatures. Do not limit feed animals during cold stress events, they need to consume as much as is needed to maintain body condition and perform.
Finally, when animals are facing an environment colder than the thermal neutral zone the increase in feed intake is accompanied by an increase in water requirement. As always providing clean water is important in helping animals combat stress.