Soybeans that have not been heat-treated can be incorporated successfully into dairy cattle rations. They provide a source of degradable and soluble protein as well as energy in the form of fat. The suggested feeding level is 10 percent of the total ration dry matter. For lactating cows the suggested feeding level would probably be no more than 4 to 5 pounds as-fed.
There are two main types of roasters used in the field - a drum roaster and high temperature air dryers where soybeans are conveyed over a perforated floor through which hot air is blown. With drum roasters soybeans are dropped into a rotating drum where air temperatures may range from 400°F to 600°F. Soybeans will remain about one minute in the hot air environment before exiting. If beans remain in the roaster longer than one minute, they can get scorched. The amount of damage to scorched beans typically is minimal.
Equipment that conveys soybeans across a perforated floor through which hot air is blown causes less scorching and may be more energy efficient than the drum roaster. This type of equipment usually is more expensive.
Researchers at Wisconsin have demonstrated the differences that occur in RUP and lysine availability when various heat-treatments are used (Table 2). It appears that optimum heat treatment for soybeans intended for lactating dairy cattle is to heat soybeans to 295°F and then steep them without cooling for an additional 30 minutes. The steeping temperature will always be less than the temperature of the soybeans exiting the roaster because the soybeans will be losing moisture by evaporation. This will cause the temperature of steeped beans to be 10 to 20 degrees cooler, depending on the moisture content of the beans.
Soybean meal is palatable, nutrient dense, high in digestibility, and a relatively consistent source of protein. It has an excellent amino acid profile. It is a concentrated source of protein and energy and is lower in fiber than most other oilseed meals.
Another name for this process is ligno-sulfate treated soybean meal. It was demonstrated that ruminal protection of soybean meal occurred when heated at 300°F for 30 minutes after mixing with xylose and adjusting the moisture content of the mixture to 17%. Non-enzymatic browning of dehulled, solvent-extracted soybean is commercially available as Soy Pass®.
Soybean hulls are a byproduct of soybean processing. They are low in lignin, relatively high in energy, a good source of rumen digestible fiber, and low in nonstructural carbohydrates. Under most feeding situations, soyhulls can be included in dairy cattle diets up to 10% of the total ration dry matter. They can be incorporated into both lactating and dry cow diets. 2b1af7f3a8