Due to summer growing conditions that have been unfavorable for soybean production and the need for hay, an unusually large amount of hay has been made from failed soybean crops in several areas of the Midwest. Farmers and cattlemen are relatively unfamiliar with soybeans as a hay crop and therefore have questions about its use. Following are some points about feeding soybean hay to beef cattle.
1. Soybeans can make very good hay and have been used widely in certain areas for this purpose, often by substituting it for alfalfa or clover. Soybean hay, according to 1984 National Research Council, will be 17.8 percent crude protein and 53 percent TDN when sun-cured and harvested at mid-bloom.
2. The requirement for protein and energy in the diet of an 1,100 pound dry cow in the last third of pregnancy (.4 ADG) is 7.8 percent C.P. and 53 percent TDN, respectively. If dry cows are given free access to high quality soybean hay, obviously protein is overfed. Mixing with a good quality grass hay will suffice for most dry cows.
3. At least 10 to 20 percent of soybean hay is wasted during feeding due to the coarse stems. However, the part that is eaten can be equal to average quality alfalfa in feeding value.
4. If soybean hay is chopped in a tub grinder, cows will eat practically all of it. However, the stem is high in fiber and low in digestible nutrients. It may be more economical to simply feed more hay and let the cows leave the stems. Rarely; however, in a drought year will excess hay be available.
5. When hay is packaged as large round bales and left unprotected from the rain, rain will penetrate the bales much more than grass hay. This can result in extreme storage losses, mold and refusal to eat by cattle.
6. Unlike other kinds of hays, soybeans can have a good feeding value when cut at any stage, from the time the pods are formed until the beans are almost fully developed and the lower leaves are yellowing, but before they drop off.
7. When the soybean seeds are nearly full size at cutting, but still green, they dry out very slowly in the pods and are apt to mold when the hay is stored. Soybean hay that contains a high proportion of beans can produce a diet too high in fat, leading to scouring, depressed appetite and digestive problems.
8. There is the potential for toxic weeds such as nightshades to be cut and baled with this hay. Nitrate toxicity due to nightshade in soybean hay is possible. The chance of animals consuming harmful material would be increased by chopping the hay for the purpose of reducing waste. A random sample of hay from several areas of the field could used to test for nitrate content. See your county extension office for testing details.