December 8, 2008


Cold weather to alter cattle's nutritional needs


As the cold weather starts, Jim Neel, University of Tennessee animal science professor has recommended some pointers in addressing cattle's needs.


Many cow/calf producers are not aware that cold weather brings added nutritional needs for cattle. Or, if they recognize that their cattle are stressed, they aren't sure how -- or what -- they should do to offset it.


Neel said cold stress occurs when animals are exposed to weather conditions which put them below their lower critical temperature. For cattle with a dry winter coat, the lower critical temperature is 32 degrees. If the coat is extra heavy, that number drops to 18 degrees. If the normal coat is wet, however, the lower critical temperature may become 60 degrees.


When the environment results in an effective temperature below the animal's lower critical temperature, Neel said the animal must increase heat production to maintain a constant body temperature. To produce more heat, the animal either must receive an increase in energy from the ration or draw on body stores.


A good rule of thumb to compensate the energy deficit created by cold stress, Neel says increase the amount of feed 1 percent for each degree of cold stress. If a wind chill is present, use that temperature.


Keeping hay in front of cattle will not necessarily take care of the problem, he said.


A 1,200-pound cow, in good body condition, needs a ration that has a minimum total digestible nutrient value of 50 percent and crude protein value of 8 percent under neutral environmental conditions. The TDN (total digestible nutrient) value is often used to indicate the energy level of a feed. Concentrates have higher TDN values than forages but do not generate as much heat. In comparison, shelled corn has a TDN of 90 percent and soy hulls, 80 percent. If hay falls below the 50 percent TDN minimum, producers should consider supplementing with an energy-dense feed.


If protein levels are too low, rumen microbes cannot efficiently digest fibre. In that case, Neel says adding supplemental protein can increase hay consumption and digestion. High-protein feedstuffs include soy meal (49 percent CP), cottonseed meal (41 percent CP) and corn gluten feed (19 percent CP). If both energy and protein are low, the supplement should contain a balance of both.


Provide some type of shelter, such as woods, hills or buildings to protect cattle from winds. Reduce mud in and around feeding areas. Cold mud on cattle draws on their energy stores and body temperature, especially in young calves.


Monitor weather reports and make adjustments in feeding 2 to 3 days before the weather front hits the area.

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