Feedlots and cow/calf operations in the beef industry who feed 500 or more has annually on grains and concentrates; maintain 500 or more beef cows; backgrounder, stocker/grower, preconditioner; veterinarian, nutritionist, consultant
Issue link: http://feedlotmagazine.epubxp.com/i/592830
6 FEED•LOT November 2015 FEEDLOT FOCUS Now is a good time to take advan- tage of the remaining nice fall weather to winterize your operation. From a nutritional standpoint, the following are some points to keep in mind regarding the effects of win- ter weather on cattle performance. Lower critical temperature is the temperature at the lower end of the thermoneutral zone. At tempera- tures below this, cattle must com- pensate by increasing heat produc- tion, and thus they will have higher maintenance energy requirements. Higher maintenance energy re- quirements mean one of two things: either cattle eat more to achieve the same amount of pro- duction (gain, lactation, etc.) or they eat the same and produce less. The lower critical temperature for cattle with dry, winter coats is gen- erally considered to be about 30 de- grees Fahrenheit (including wind chill). The lower critical tempera- ture is dependent on body condi- tion, coat thickness, wetness, and ability to find shelter from the wind. Below this temperature, en- ergy requirements of cattle in- crease approximately 1% for each degree the wind chill is below 30 degrees. Therefore, if the wind chill is 0 degrees, maintenance energy requirements will increase by 30%. Moisture has a tremendous ef- fect on maintenance energy require- ments of cattle during cold weather. The lower critical temperature for cattle with wet hair coats is gener- ally considered to be 59 degrees Fahrenheit. Dry hair coats trap air and provide a layer of insulation to help cattle cope with cold stress. As their coats become wet, the hair lays flat and the cattle are de- prived of their layer of insulation. Energy requirements of cattle with wet coats also increase much more rapidly than requirements of cattle with dry coats. For every degree the wind chill is below 59 degrees, cat- tle that are wet require 2% more en- ergy to maintain body temperature and body weight. As cold stress increases the maintenance energy requirements of cattle, nutrition must compen- sate for increased energy require- ments in order to maintain per- formance or body condition score. The appropriate strategy depends greatly on the type of cattle and feeding situation. Feedlot cattle on rations de- signed for maximum gain are consuming high levels of energy compared to their maintenance re- quirements. Dry matter intake of feedlot cattle increases during cold weather, compensating somewhat for the effects of temperature. However, wet pen surfaces con- tribute to wet cattle – and can po- tentially increase maintenance energy requirements by nearly double. We recommend removing snow from pens any time accumu- lation could lead to wet or muddy pens. The cost of doing so will be more than made up for in cattle health and performance. Likewise, with low quality roughage being in- expensive, bedding pens to keep cattle dry makes financial sense, especially when receiving calves. Storm rations should be used BY JEREMY MARTIN, PH.D.