Soybean forage has been used quite a bit with cattle and they seem to like it. With hay, they may pick and choose, and not eat the very coarse stems. If looking at harvesting for forage, research shows the best time to harvest is when the bottom leaves are turning yellow and seeds are developing, Owens said. If it appears seeds will not develop, then the yellow bottom leaves become the criteria. Rob Pritchard, a ruminant nutrition researcher at SDSU, said if seeds are developing, he'd be inclined to harvest them later as seed rather than forage and include it like grain in livestock diets.
Soybeans can work as pretty good source of energy and protein in the diets of cattle and sheep.
We've answered a lot of questions this summer about replacing part of the corn in the diet with soybeans. Pritchard points out that putting up soybean hay can be tough, because the leaves and stems are so different, physically, it's hard to get stems dry without getting the leaves over-dry.