Weekly, Oklahoma State University Extension Beef Cattle Nutrition Specialist Paul Beck offers his expertise on the beef cattle industry. This is part of the weekly series known as the “Cow Calf Corner,” published electronically by Dr. Derrell Peel, Mark Johnson, and Beck. Today, he provides discusses supplementing beef cows during cold weather.
Last week we discussed some of the management tips for minimizing the impacts of cold weather on beef cows (https://extension.okstate.edu/programs/beef-extension/cow-calf-corner-the-newsletter-archives/2025/january-6-2025.html). The question arises, how much extra supplement is needed to get cows through these weather events?
Let’s consider a 1200-pound pregnant beef cow in the third trimester fed a prairie grass hay that is 90% dry matter (DM), 7% crude protein (CP), and 56% total digestible nutrients (TDN). This cow requires 1.85 pounds of CP and 12.5 pounds of TDN (DM basis) to meet her requirements and would be expected to eat about 24 pounds of hay per day (1.8% of her bodyweight on a DM basis). The 24 pounds of hay plus 2 pounds of 20% range cubes will meet these cows’ requirements for CP and TDN in normal conditions. When daily temperatures drop, TDN requirements increase by 1% for every degree below the lower critical temperature (LCT). For a cow in good condition and a thick winter haircoat the LCT is 32°F. When temperatures get down to 20°F her requirements increase by 12%, from about 12.5 pounds of TDN per day to 14 pounds of TDN per day. As we add more supplement hay intake will decrease, so to meet the shortfall in energy she will require 3 pounds of additional cubes per day for a total of 5 pounds of cubes per day.
For a thin cow with a thin hair coat, it gets to be more critical. She is already needing to gain body condition to increase her chances of rebreeding for the next calf crop so we should already be feeding around 4 pounds of cubes a day. Her LCT is around 40°F. So, when temperatures fall to 20°F her requirements increase by 20% from 13.3 pounds of TDN per day to 16 pounds of TDN per day. To offset this energy deficiency of 2.7 pounds of TDN we need to provide her with 7 additional pounds of cubes per day to keep her from losing additional body condition for a total of 11 pounds of supplement per day. Feeding this much supplement is expensive and hard to manage.
Much of this energy deficiency could be offset if we can provide hay that is higher in quality during the winter storms. But it still shows how important it is to keep our cows in good condition before winter weather sets in. Contact your local Cooperative Extension office for assistance in developing a winter-feeding program for your cowherd.
