Vern Anderson and Jon Schoonmaker
Soyhulls are a co-product of oil extraction from the soybean. The laboratory analysis of soyhulls indicates it is high in fiber; however, the highly digestible fiber is useful to ruminants. High dietary levels of cereal grains, which are high in starch, can decrease forage digestibility. Soybean hulls offer an alternative to high-starch grains, as they contain significant levels of digestible fiber and in many growing diets, can be used as an energy source with similar value to grains. The objective of this trial was to determine the optimum level of soyhull inclusion needed to maximize cattle performance in receiving diets for weaned calves.
One hundred-sixty crossbred steers from 40 different ranches in North Dakota (initial wt. 635.2 ± 3.3 lbs.) were allotted by weight and source to one of four receiving diets (4 pens per treatment, 10 head per pen) to determine the optimum level of soyhulls to maximize cattle performance. Diets were formulated to contain 0, 15, 30, and 45% soyhulls, replacing corn in the 70% concentrate receiving diets. The remainder of the diet consisted of field peas, corn silage, vitamin and mineral supplement with Rumensin® and triticale hay. Crude protein concentrations of the diets were 13.3%. Experimental diets were fed for 42 days, after which cattle were placed on a common finishing diet.
Overall, animal performance during the 42-day receiving period was very satisfactory. Calf weight, dry matter intake, and feed efficiency did not differ (P>.21) among treatments at any time during the trial. Average daily gains were greater for the 0%, 15%, and 45% soyhulls diet during period 1 than the 30% diet (P<.10). Period 2 gains favored the 0%, 15%, and 30% diets (P<.01) with a linear decrease in gain with increasing soyhulls level. Overall, gains were similar for the 0% and 15% diet but the 30% diet was not different from the 0% (P<.05). Steers gained 4.13, 4.33, 3.96, and 3.76 lbs. per day for 0%, 15%, 30%, and 45% soyhulls diet, respectively.
Soybean hulls offer an alternative to high-starch supplements in receiving and growing diets. Results from this study indicate that using soyhulls as a concentrate component in receiving diets was most effective at the 15 to 30% level. Any potential negative effects associated with corn in a receiving or growing diet may have been reduced by the addition of soyhulls. Soyhulls may have provided the rumen with more digestible fiber and supply more degradable protein compared to corn. At 70% concentrate, it may also be possible that the forage concentration of the diet was not high enough to elicit a negative associative effect. n