Soy Hulls as a Supplement for Feeding Cattle

Introduction

Livestock producers in West Virginia are frequently seeking low-cost feed alternatives or supplements. By-product feeds such as soy hulls can fill this need. Soy hulls are a by-product of soybean milling and are an excellent supplement for cattle, sheep and goats. Due to the predominant form of energy in soy hulls being fiber, they complement forage-based rations well. Considerable research has shown the nutritive value of soy hulls to ruminants and their ability to enhance forage digestibility.

How are Soy Hulls Produced? 

Soy hulls are a by-product of the soybean oil milling process. Using solvent extraction procedures, the soybean is separated into two parts, the oil and protein-carbohydrate-fiber meal. Soybean hulls and a fraction of the meat fines are removed. The hull fraction then passes over a sifter and is separated into hulls, meat and fines. The soybean hull and meat fractions go to the secondary dehulling step, and the hulls are removed from the soybean meats and passed to the hull toaster to destroy urease activity. 

Following toasting, the remaining hull fraction is ground to the desired particle size and either pelleted or sold as bulk. Bulk or loose soy hulls are bulky and often dusty, and therefore, are often pelleted to increase density (bulk density is increased three times) and reduce transportation costs. Pelleting whole or ground soybean hulls does not affect intake or dry matter (DM) and neutral detergent fiber (NDF) digestibility of rations. 

Nutrient Content of Soy Hulls 

Average Nutritional Content of Soy Hulls (100% Dry Matter Basis) 

Soybean hulls consist mostly of energy in the form of fiber but have a slightly higher crude protein content than corn grain. Because the fiber (energy) component is low in lignin, it is highly digestible. Even though NDF) is approximately 67%, the small particle size of soy hulls makes the effective NDF much lower.  

It is important to note that by-product feed sources can vary widely in their nutrient content and producers should always sample by-product feeds themselves, especially when buying in bulk. 

Uses in Beef Cattle Diets 

Soy hulls can be used for winter supplementation of beef cows, or as a supplement for growing livestock on pasture or being fed hay. In addition, soy hulls are a good fit for stocker cattle, backgrounding operations and replacement heifer rations. They are an excellent source of readily available energy in forage-based diets. Several university research studies with growing beef cattle have yielded consistent results supplementing with soybean hulls.  

Compared to corn, soy hulls contain more protein. They contain less TDN per pound than corn but are equal to corn as a supplement for cattle consuming forages because of their positive impact on forage intake and digestibility.   

It is always preferred to provide access to long-stem roughage, whether it be hay or grazing, to slow passage rate and increase ruminal retention time. Soy hulls are most effective when limited to 30% of the animals' intake. 

Soy hulls can be fed alone but have a high passage rate and a much lower digestibility unless the diet includes at least one-third long-stem forage. In addition, when fed alone soy hulls are conducive to bloat, especially when fed at greater than seven pounds/head/day. Research studies show that issues with bloat can be minimized with the use of long stem hay (an effective fiber source) and or feeding an ionophore such as Rumensin or Bovatec.   

Researchers at North Carolina State compared corn to soybean hulls in a 107-day study with 520-pound growing calves. All calves were allotted 7.30 pounds of the grain mix in addition to free access to a 12% crude protein grass/clover hay. The authors concluded that soybean hulls have similar feeding value to corn in a hay-based diet.   

A winter feeding research project was conducted with dry, gestating, beef cows to look at soybean hulls as a supplement to hay as a winter feed. Cows grazed on stockpiled tall fescue and were fed free choice tall fescue hay when pasture became short. Cows were fed 4 pounds of soybean hulls to substitute for 5.3 pounds of hay daily.  

Over the course of a 118-day trial, cows supplemented with soybean hulls lost 73 pounds less than the cows consuming hay and approximately 620 pounds of hay were conserved for each cow supplemented with soybean hulls. 

Other research has been done using soybean hulls as a replacement for corn in steers maintained on forage-based diets. In a study where steers were maintained on tall fescue grass, one set of steers were fed four pounds of soybean hulls, and another set was fed four pounds of corn. A third set of steers received no supplement. The steers gained similarly on soybean hulls and corn (two pounds/day), with both being greater than the gain of steers that were not supplemented (1.5 pounds/day).

Soy hulls also work as an excellent creep feed. Soybean hulls have been found to be equal to corn for rate and efficiency of gain when fed as a creep supplement to steer calves. In addition, many backgrounded calves have been weaned onto free-choice soyhulls and gained more than two pounds per day for a 45-day backgrounding period. Soy hulls are extremely palatable and thus make a great choice in weaning diets. 

There are limits to soybean hulls being equal to corn. Feedlot steers fed corn or soybean hulls as the primary dietary energy source had similar intakes and daily gains. However, the soybean hull diet had poorer feed conversions than the corn diet.  

Soy Hulls and Fescue Toxicity 

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