Corn residue can be a valuable grazing resource for cattle. This year especially with a fairly open winter, stalks have been open for grazing for quite some time. Typically, corn residue can run around 5-6% Crude Protein (CP) and 50-60% total digestible nutrients (TDN) which is a measure of energy. For some classes of livestock this may be enough to get by without supplementation, but for others, some extra feed is required.
When we think of animals out on stalks, we often picture the cow, but weaned calves that need a place to overwinter may be an option to consider. Utilizing stocks as part of a maintenance diet for these animals won’t be maximizing gain, but might be a cost effective option under the right circumstances. Even without pushing gains, calves on stalks require supplementation to keep from losing weight. For example a 600 lb. calf that we want to gain 1.5 lb./day needs to consume 9.2 lb. of TDN and 1.5 lb. of CP. On stalks alone, a calf will fall well short of this, only consuming 6.8 lb. of TDN and .6 lb. CP. Both energy and protein will need to be provided for the calf to reach our target gains. UNL research has shown 4 lb. of dried distillers grains per day provides enough supplemental feed to reach the 1.5 lb. gain we want, but with feed prices high, pricing out other supplemental options may be worth the effort.
For dry, spring calving cows, the picture is a bit different. A dry cow in the second trimester is at one of the lowest points for nutrient requirements she will have during the year. Up until late gestation, little or no supplement on stalks should be needed. Keep a close eye on the herd to make sure condition doesn’t slip as available forage is reduced with grazing and provide a free choice mineral with phosphorus, copper, zinc, and Vitamin A. While supplement isn’t required, this may be an opportunity to put some condition on animals that are a bit on the thin side. A 5 year UNL study found 2.2 lb. of dried distillers grain on a dry matter basis supplemented daily was able to raise body condition scores 0.5 a point with no impact on calf birth weight or subsequent pregnancy rates.
Last, we need to look at summer and fall calving cows that are still lactating at this point and supporting a calf. For these animals, both the quality and amount of feed needed is increased. A 1350 lb. cow will only be able to consume 13-15 lb. TDN and 3-5 lb. CP while grazing stalks. Even with a protein lick tub and animals consuming one lb. daily, the diet energy and protein provided are well below what is required.
For summer calving cows, UNL studies have shown 5.5 lb. dried distillers grains on a dry matter basis fed daily resulted in calf gains of 1.43 lb. per day from December to March. While a similar group in dry lot gained more, the lower cost of corn residue made the net income for calves on stalks higher. Fall calving cows in peak lactation are at the highest their nutrient requirements will be all year. For these animals, even high quality alfalfa hay won’t provide enough energy to meet their demands. While every diet should be adjusted for your animals and conditions, 8 lb. of dried distillers grains per pair on a daily basis should meet the cow’s needs and provide a bit of additional supplement for the calf.
Corn residue can be a very cost effective forage resource, but using it correctly and continuing to meet animal needs while grazing is critical to success. Make sure you adjust supplementation to the class of livestock you are grazing and keep an eye on condition to make adjustments as conditions change.
-Ben Beckman is a beef systems Extension Educator serving the counties of Antelope, Cedar, Knox, Madison and Pierce. He is based out of the Cedar County Extension office in Hartington. You can reach him by phone: (402) 254-6821 or email: firstname.lastname@example.org .