Page 3 - December Newsletter

Livestock By: Heather FoxworthyMeeting Nutritional Requirements for Cattle in Cold WeatherManaging spring calving cattle through the winter often means supplementing extra feed to account for the increasing needs of cows in the third trimester of pregnancy. However, there are sev- eral factors that influence the nutritional requirements of live- stock beyond pregnancy and stage of production. They include, but are not limited to age, body condition score, body weight, physical activity, and finally weather. As most cattle producers know, cold weather and winter storms can significantly increase the nutritional requirements of cattle who must endure them, es- pecially those who are accustomed to milder and drier conditions. Cattle reach maximum performance when they are managed in the optimum temperature which falls in a window where temper- atures are neither too cold nor too hot called the thermoneutral zone. More specifically, the weather’s effect on cattle perfor- mance is influenced by the air temperature, wind, humidity, and solar radiation which in combination create the effective ambient temperature. If cattle are in an environment outside of the opti- mum effective ambient temperature, their performance may be depressed due to additional physiological or nutritional demands.In many cases, cattle experiencing cold weather are not receiving maintenance energy from their diet that is meeting their require- ments. While cold weather increases the need for energy, require- ments for protein, minerals, and vitamins remain unchanged. Understanding the weather and its effect on cattle and how the issue should be addressed is dependent on things like the ani- mals’ current hair coat, weather trends, as well as their access to a windbreak. However, as a general rule of thumb, the energy in the ration should be increased by one percent for each one degree drop in temperature below the critical temperature range, the range that cattle find optimum for performance.As mentioned things like the animals’ hair coat is going to im- pact how they handle cold weather stress. For example, the lower critical temperature for beef cattle with a wet or summer coat is 59 degrees Fahrenheit, while those with a dry, heavy winter coat do not become cold stressed until they dip below approximately 18 degrees Fahrenheit. Refer to Table 1. to view the range of hair coat descriptions and their associated critical temperature where cattle begin to suffer after the weather dips below that critical value. This demonstrates the impact of previous weather trendsTable 1. Estimated Lower Critical Temperatures for Beef Cattleadditional energy resources to keep them comfortable and pro- ductive during that time.Wind chill is another factor that should be considered. Instead of only considering the critical temperature, a producer must also evaluate the combination of wind and temperature’s effects on those animals. Refer to Table 2. to review the varying combina- tions of wind and temperature to better understand the wind chill factor. If the combination of the two falls below the critical tem- perature of an animal based on its hair coat, increase the energy in the ration by one percent for each degree below the critical value. For example, if the temperature is 40 degrees and the wind speed is 25 mph, the energy in the ration for cattle with a dry heavy winter coat should be increased by 6% to account for their increased needs. If cows however have shelter from the wind in the form of a solid windbreak or shelter, the effective ambient temperature is the same as the air temperature and the table does not have to be used.Table 2. Windchill Factors for Cattle with a Winter CoatWindSpeed(mph) -10 -5 0 5Calm510152025303540Temperature (OF)10 15 20 25 30 35 40 45 50-16-21-25-30-38-46-60-78-11-16-20-25-32-41-55-73-6-11-15-20-27-36-50-68-1-6-10-15-22-31-45-633-1-5-10-17-27-40-5830-5-12-21-35-5313840-7-16-30-48181394-2-11-25-4323181492-6-20-382319147-1-15-3333282419123-10-2838332924178-5-234338342922130-18Coat DescriptionWet or summer coatDry fall coatDry winter coatDry heavy winter coatCritical Temp. 5945 32 18Table recreated from the “Beef Cow Nutrition Guide” by T. T. Marston, D. A. Blasi, F. K. Brazle, and G. L. Kuhl, 1998.Tables 1. and 2. should be used appropriately to determine how and when to give cattle additional energy to tolerate cold winter storms. To better prepare cattle against cold weather and storms, producers should place emphasis on providing higher quality feeds in the diet prior and during cold weather to meet their in- creasing nutritional requirements. This demand for energy from the diet can be accomplished by feeding a high-quality forage or adding or increasing the amount of a high-energy feedstuff like grain.For more information or resources of winter management of beef cattle, please visit or call the Cheyenne County Extension Office at (785)332-3171.For more resources and event announcements, please fol- low us on Facebook at K-State Research and Extension Sunflower District.Table recreated from the “Beef Cow NutritionGuide” by T. T. Marston, D. A. Blasi, F. K. Brazle,on the cattle’s ability to handle cold weather. If cold weather hits unexpectedly while livestock still have their summer coats, they are going to be much more sensitive to the cold and will need-10-505101582025303528404550K-State Research and Extension is an equal opportunity provider and employer.