Cold stress in cattle can reduce weight gain, pregnancy rates, and calf survival.
Hay intake will increase during cold weather; providing extra hay can help reduce cold stress. Heat is produced from the digestion of hay that will help keep cows warmer.
More heat is produced from the digestion of hay than the digestion of concentrate feeds. Never suddenly increase the amount of rapidly fermentable feeds in the diet (e.g. corn, soybean hull pellets, cubes, etc.) because this can lead to subacute acidosis and other problems.