Nar Gurung, Darrell Rankins, Jr., N. Jerry Van Dyke, Rob Peacock, and Bill Gregory

Replacement heifers and stocker steers are often fed diets containing broiler litter. The diet usually consists of equal quantities of litter and an energy source, such as corn or hominy feed. Obviously, the most expensive portion of this diet is the energy source. Soyhulls are a very digestible fiber source that can be a good supplement to cattle consuming forage-based diets. The objective of this study was to replace up to half of the corn with soyhulls and measure subsequent performance and nutrient digestibilities by stocker steers.

The study was conducted at the E.V. Smith Research Center Beef Unit in Shorter. Thirty-two predominantly Angus steers (average weight of 608 pounds) were placed in pens with four steers per pen. Steers were then fed one of four diets over a 112-day period. The diets were as follows: (1) 50% broiler litter and 50% cracked corn; (2) 50% broiler litter, 37.5% corn, and 12.5% soyhulls; (3) same as Diet 2; and (4) 50% broiler litter, 25% corn, and 25% soyhulls. All diets were fed free-choice. Diets 1, 3, and 4 were supplemented with 3.4 pounds of chopped coastal bermudagrass hay per steer per day. Diet 2 included no hay. The broiler litter had been deep-stacked and covered prior to feeding. In addition, all diets contained Bovatec.

As inclusion of soyhulls increased in the diet, average daily gain also increased. The fastest and most efficient gains were observed in the cattle being fed the diet containing the highest inclusion of soyhulls (see table). The slowest gains were observed for the cattle receiving Diet 1, no soyhulls. Similarly, the diet containing 12.5% soyhulls produced intermediate gains to the other two. Diet 2 contained 12.5% soyhulls but the cattle were not given supplemental hay; this resulted in gains similar to cattle fed no soyhulls and supplemented with hay. No difference in feed intake was observed among the cattle fed varying levels of soyhulls. However, hay supplementation increased intake over the steers not being supplemented with hay. When feed costs are combined with the performance data there is an obvious advantage to using soyhulls. Cost per pound of gain was calculated using December 1997 Alabama prices (includes delivery to Shorter) that were as follows: corn, $115 per ton; broiler litter, $23 per ton; soyhulls, $78 per ton; hay, $60 per ton; and Bovatec, $5 per pound.

Nutrient digestibilities also were determined for each of the four diets. In general, Diet 4, which contained the greatest concentration of soyhulls, was the most digestible. Comparisons for Diet 1 with no soyhulls versus Diet 4 with 25% soyhulls showed that overall diet dry matter digestibility was 71% vs 74% and fiber (ADF) digestibility was 66% vs 70% for Diet 1 vs.Diet 4, respectively.

Diet 2 (no hay) was included to determine if the soyhulls would replace the coarser fiber being provided by the grass hay. When Diet 2 is compared to Diet 3 (same ingredients plus the hay supplement), it is apparent that a less digestible fiber source is more beneficial. When the study was initiated it was assumed that the highest percentage of soyhulls (25%) would be the maximum amount that could be used. However, 25% soyhulls was the best diet and the maximum was probably not reached. Currently, a study is being conducted to evaluate higher concentrations of soyhulls.

Based on these results, soyhulls can replace half of the grain in a broiler litter/corn diet without compromising performance. In fact, performance was actually enhanced by substitution with soyhulls, presumably by effects on digestibility, making them a very economical alternative to corn in a litter-based diet. Even though the soyhulls are a digestible source of fiber, additional fiber (i.e., hay) should be offered for optimal performance.