B. C. Allison, M.H. Poore and R.L. McCraw

Agricultural processing yields by-products that have significant feeding value for livestock and are sometimes available at attractive prices. The value of these by-products is generally calculated relative to the value of corn and soybean meal, assuming that feed intake and weight gain will be the same if they are included in balanced diets.

Soy hulls are a by-product of soybean processing for oil and soybean meal. According to the 1984 NRC publication, Nutrient Requirements of Beef Cattle, crude protein and TDN values are 12% and 64%, respectively. However, most of the soy hulls in this area check higher than this in protein. The energy value is also underestimated, especially relative to other feeds such as corn. Soy hulls contain highly digestible fiber which makes them an excellent supplement for high forage diets.

A previous study at this location showed soy hulls to have a feed value comparable to corn and soybean oil meal for growing beef calves in hay-based diets. This project was designed to further evaluate the feeding value and economics of soy hulls (SH) rela tive to corn (C) and soybean oil meal (SBOM) in hay and corn silage-based stocker rations.

Materials and Methods
Ninety head of mixed breeding M-1 grade 400-500 pound steer feeder calves were purchased from state graded feeder calf sales October 6th and 11th, with an average purchase weight of 462 pounds and average purchase price per cwt. of $101.91. The calves were processed within 16 hours after arrival at the Moun tain Research Station and were then grazed together until November 30th when the feeding trial was initiated.

A value was determined for the calves on this date that included the pre-conditioning and pasture cost from the date of purchase to November 30th. On November 30th, 80 head of uniform steers were selected for this trial and randomly assigned by breed and weight to one of 8 pens, 10 head per pen, 2 pens per treatment. Weights were taken on two consecutive mornings before feeding at the initiation and termina tion of the trial to determine weight gains.

The calves were fed rations balanced to provide 12.5% crude protein (CP) and 67.5% TDN. Ingredient prices of 26, 80, 140, 241 and 100$/ton, were used for corn silage, hay, ground corn, soybean meal, and soyhulls, respectively. The soyhulls contained 16.6% crude protein. All diets were formulated to provide at least 200 mg lasalocid/head/day.

Four pens received free choice hay supplemented with 6.5 pounds of grain mixture. Two of these pens received a ground corn plus soybean oil meal mixture (82% corn and 17% SBOM) and two a soy hull mixture (99% SH). Four pens received a free choice ration that consisted of 75% corn silage plus 25% grain supplement (dry basis). The grain supplement for two of these pens was 51% corn and 48% SBOM and the grain supplement for the other two was 17% SBOM and 82% SH. All 8 pens received trace mineralized salt blocks free choice.

Results and Discussion
Table 1 shows performance data and an economic analysis. Dry matter intake and average daily gain was lower for the hay-based diets than for the silage- based diets, but the source of concentrate did not influence intake or gain. An interaction was observed for gain in that gain was higher for C+SBOM than SH in hay-based diets but lower for C+SBOM than SH in silage-based diets.

A value of $93.97/cwt. was established for the cattle at the beginning of the trial, and final value was assumed to be $82.00/cwt. for the cattle in the four hay treatment groups and $80.00/cwt. for the cattle in the four corn silage treatment groups. The reason for this difference in value was the corn silage cattle weighed approximately 60 pounds more than the hay cattle at the conclusion of the trial. The total feed costs for the diets containing soy hulls averaged $17.32/hd. (hay ration) and $8.63/hd. (corn silage ration) lower than for the diets containing C+SBOM. Likewise, average feed cost/cwt. of gain was $7.00 lower for SH in the hay ration and $4.04 lower in the corn silage ration. The average return over feed costs and average net return, reduced by $25 per head fixed costs, were $12.56 per head higher for the SH diet than for the C+SBOM diet for the cattle receiving hay rations and $13.18 per head higher for the SH diet than the C+SBOM diet for the cattle receiving corn silage rations. Based on the crude protein and energy values the soy hulls should have been worth $144. 29/ton. However, based on the net returns, the realized value of soy hulls was $139.54/ton in the hay ration and $186.14/ton in the corn silage ration.

This trial demonstrates that soy hulls can be utilized very economically in growing steer rations, based on either hay and corn silage, to produce weight gains comparable to those expected from C+SBOM. The economic analysis of this trial indicates that the actual feeding value of soyhulls is equivalent to or greater than what is expected, based on their protein and energy values. This value is well above the current market price, and producers should consider them when developing feeding programs.

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