In wintertime, cold temperatures, wind, and moisture necessitate increasing cattle’s nutritional needs for energy. The energy requirement increases generally by 1% for each degree in which the wind chill is below 32 degrees. This means that even minor decreases in temperature impact the energy that cattle require to sustain their bodily functions, resulting in the need for more dietary energy to offset the extra energy needed to combat the cold. The Lower Critical Temperature (LCT) is the temperature at which the animal’s bodily function maintenance requirements increase to the point where their performance is negatively affected. The LCT can differ between animals, as factors including body condition score (BCS), winter precipitation, and hair/coat thickness all have an impact. It is thought that the LCT is when cattle experience cold stress.
Cattle not receiving rations that meet their nutritional requirements can suffer performance issues. Cows deliver lighter, weaker calves and produce lower-quality colostrum to nourish their offspring. Weaning weights for these lighter calves will be diminished.
The mothers will later come into heat, which hurts conception rates.
Avoiding this cycle requires a sound nutritional and management strategy.
Battle the elements
Obviously, part of cattle management is abating the harshness of winter. Shelter from the wind, snow, mud, and freezing rain all help keep animals warmer and dry. However, the main component of cold stress is cold temperatures. Proactively mapping out a nutrition plan, including supplements, and enacting that strategy early helps the cattle be physically prepared for cold instead of reacting to it after their BCS is already affected.
What’s in your feed?
The team at Sioux Nation Ag Center has devoted a great deal of time to touting the importance of feed testing. The resources section of our website offers numerous articles, podcasts, and videos on this topic. Knowing the feed value of your feedstuffs
is essential in determining what should be added to balance out the ration and compensate for the extra energy necessary to combat the cold. As cows tend to spend less time grazing as the weather declines, the challenge of maintaining proper quality feed intake increases.
Differing nutritional requirements
We already stated that a cow’s energy requirement (TDN) generally increases by 1% for each wind chill degree below 32 degrees. BCS can drastically affect this ratio.
TDN is determined by conducting a digestion trial and summing the digestible protein and carbohydrates plus 2.25 times digestible ether extract. Ether extract (EE) is the fat or lipid portion of the feed.
Cattle under a BCS of 6 need 30% more energy per point under 6 when the temperature drops to 32 degrees. We must also factor into the equation the TDN increase of 1% for each degree of temperature drop. Finally, the cow’s stage of pregnancy also comes into play when properly determining energy requirements.
Taking into consideration the nutritional value of your feedstuffs and the daily temperature, while monitoring BCS will help you stay ahead of the changing nutritional needs of your herd. Higher quality supplements to the winter diet may be required.