Roasted Soybeans for Dairy Cows

Nutrition Update
Volume 9 No.4, February 1999

This year has seen interest in the use of full-fat soybeans as a supplement for dairy cattle, particularly in the southeast part of the province.

Fat contains over two times the amount of energy found in grain. This makes it a good energy supplement for early lactation cows. There are many different sources of fat available: commodity fats (tallow, lard, vegetable oils), commercial "rumen inert" fats and whole oilseeds. The most common oilseed fed to cows in Manitoba is sunflowers.

Sunflower and canola seeds contain 40% oil and 20% protein. Soybeans contain 20% oil and about 40% protein. Soybeans are palatable and can be fed either raw or roasted. Roasting increases the UIP (undegradable intake protein) of soybeans from 25% to 60% and reduces the soluble protein from 40% in raw beans to 10%. These changes make roasting soybeans advantageous in high alfalfa haylage diets which are already extremely high in soluble and and low in UIP. Raw soybeans fit well into diets with corn silage, dry hay and grain.

Over heating of beans can render them indigestible to the animal. Under heating will not improve the UIP values. An analysis called the protein dispersibility index (PDI) can be used to determine the effectiveness of heat treatment. If the PDI is more than 14, the beans have not been heated properly or uniformly. Norwest Labs charges $30 + GST for a PDI and Dairyland Labs in Wisconsin charges $27 US.

Soybeans should be coarsely ground prior to feeding. Fine grinding will cause oil to be released in the rumen causing upsets in bacteria populations and reduced fiber digestion. Fine grinding of raw soybeans in the summer can cause rancidity in the beans and off feed problems in the cows. Soybeans can be fed whole but with a decreased digestibility.

General recommendations for roasted soybeans are to feed no more than 6 lbs roasted soybeans per cow per day. Raw soybeans should be limited to 4 lbs/cow/day because of antinutritional factors.

Dr. Mike Hutjens suggests the following procedure to determine if soybeans are a cost effective addition to a dairy diet. Using feed evaluation constants and corn and soybean prices of $110/tonne and $230/tonne, respectively, the value of raw soybeans is $215.75/tonne.

1. .32 X $110 = $ 35.20

2. .785 X $230 = $180.55

3. $35.20 + $180.55 = $215.75

Roasted soybeans are worth $50 to $100 a tonne more depending on UIP improvement and whether UIP is needed in the diet.

For More Information contact your Local Specialist or MAFRI GO Teams Office or Centre.