Consider Soybeans as Alternative Forage for Dairy Cattle

 BROOKINGS, S.D. -- Harvesting soybeans for forage is an option producers should consider when dry conditions are likely to hurt soybean yields or when producers are facing a shortage of roughage.

South Dakota State University Extension Dairy Specialist Alvaro Garcia said to make an economically sound decision, first evaluate whether the crop is worth harvesting for the seed or if it would be more beneficial to use it as forage source in place of more expensive forages. Soybeans are a legume and can make good feed. The decision on whether to harvest the beans or use the plant as forage must be made on an individual field and farm basis.

Garcia said it is also important to keep detailed current and future feed inventories, and to strategically allocate feed taking into consideration the animal’s production potential.

Using alternative forages such as soybeans will help stretch the availability of the traditional forages whose yield would likely be lower in a drought year such as this.

The decision on which method to use to preserve the forage depends on its current stage of maturity of the crop.

Baled soybeans: The nutritive value of a soybean plant when harvested at the right stage can be comparable to early bloom alfalfa. Baling should be done when the pods are almost full with seeds and the lower leaves are just starting to turn yellow, but before leaves start to fall off. At this maturity stage the digestibility of the pods exceeds that of stems by as much as 25 percent and contributes significantly to the overall nutritive value of the whole plant.

The stems tend to dry slowly, so longer wilting periods are usually necessary. Conditioning might be important in order to achieve a similar rate of dehydration of stems and leaves and bring total moisture below 25 percent. As leaves tend to shatter easily, raking should be kept to a minimum.

Soybean silage: Moisture content is important if ensiling. Ideal moistures are similar to those recommended for alfalfa haylage.  Aim for 35 to 40 percent dry matter. Direct cut soybeans make very wet silage with DM contents between 22.1 and 30.1 percent. Ensiling at higher moisture will result in higher effluent losses and greater risks of clostridial fermentation.

As with other legumes, buffering capacity is relatively high and can result in fermentation problems. Using inoculants may help reduce these problems and mold growth.  Ensiling should be done just before the pods are full. Waiting until complete maturity results in forage of lower digestibility, and can also lead to fermentation problems due to the high oil content of the seeds. To avoid this problem, mix one-third corn plants with two-thirds soybean plants.

Work at Ohio State showed that corn provides soluble sugars to speed up the fermentation and dilutes the fat content in the soybeans. Always verify the herbicide restrictions when using soybeans for forage.
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Contact: Alvaro Garcia, (605) 688-5488
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Lance Nixon, Editor
AgBio Communications Unit
South Dakota State University
ACC, Box 2231, Rm 200
Brookings, SD 57007
Telephone: (605) 688-4653
Lance_Nixon@sdstate.edu