I can’t count the number of times I’ve been asked this question in the last couple weeks, and unfortunately the answer is “it depends”. It depends on the quality and quantity of forages available, the size, body condition and stage of production of the cows, the environment the cows live in, what alternative feedstuffs are available, and what options you have for feed delivery.
One of the biggest variables this year is forage quality. We are seeing very wide ranges on the energy value of hays tested through the Iowa Beef Center forage testing project. For example, the grass-legume hay samples averaged 56% TDN, but they ranged from a low of 48% to a high of 82%. If we balance for the average of the grass-legume hays we are underfeeding those cows fed the 48% TDN hay and are overfeeding the cows receiving the 82% TDN hay, and neither of those situations are good for the cow! The protein situation is also variable with the average of 13% CP but a range from 8 to 21% CP. On average these hays will meet or exceed the crude protein requirement of gestating cows; however the cows fed the 8% CP hay will need protein supplementation.
Bottom line? Test your hay to determine the nutrient content before balancing winter cow rations. Talk to your county Extension office or Extension Beef Specialist for more information or help. Then, we can balance a ration to meet your cow’s needs.