1995 Animal Science Annual Report

Use of Soybean Hulls in Hay-based Rations for Growing Cattle

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


Rations balanced and fed to beef cattle using hay and grain seldom result in the expected performance or weight gain. The reason is thought to be that substituting high levels of concentrates for roughage depresses roughage digestibility. The microorganisms in the rumen that digest roughages (hay) need a near neutral pH environment. As grains are added to a roughage ration, rumen acidity increases or pH of rumen fluids is lowered, which favors microorganisms that digest starch (grain) and retards microorganisms that digest cellulose (hay). This project was designed to evaluate the value of feeding various levels of soyhulls in hay-based rations for stocker calves. Soyhulls are a by-product of soybean processing for oil and soybean meal production. Crude protein and TDN values are listed at 12% and 77%, respectively. However, analyses of most soyhulls in this area indicate a higher level of protein. The difference may be due to amount of soybean particles contained. Soyhulls contain about 50% fiber (ADF) but are highly digestible, which makes them comparable to corn as an energy source in high forage diets. Previous studies at this location showed soyhulls to have excellent feed value and to be an economical ration ingredient for growing beef calves.

Materials and Methods

Steer feeder calves of mixed breeding, weighing 400-500 pounds and grading M-1, were purchased from state graded feeder calf sales September 5 and 9. Average purchase weight was 444 pounds.

The calves were processed after arrival at the Mountain Research Station. Processing consisted of ear tagging for identification purposes, administering a growth implant, weighing, de-worming, treating for grubs and lice, injecting vitamins A and D, and vaccinating against the clostridial diseases, Haemophilus somnus, IBR, PI-3, BVD, BRSV and Pasteurella hemolytica. They were given booster vaccinations on October 7 and treated again for lice on December 27.

On November 28, 80 head of uniform steers were selected and randomly assigned by breed and weight to one of eight pens, ten head per pen, two pens per treatment. Weights were obtained the mornings of November 28 and 29. The average was used as a starting weight Full weights were obtained on the mornings of March 21 and 22 and the average of these two weights was used as a final weight.

All calves were fed once daily all the ground hay they would consume. Two pens of calves received no supplemental grain. Two pens each received either 2.5, 5.0 or 7.5 lb of soyhulls per head per day. All received Bov-A-Min Extra Mineral7 free choice. Prices of soyhulls ($100/T) and mineral($562/T) are actual prices for delivered product. Price of hay($50/T) which was produced on the research station is estimated.

Results and Discussion

The table shows data on an individual basis averaged across replicates for each treatment.

Weight gains increased (P<.01) linearly with increasing levels of soyhulls in the diet. Dry matter intake was similar for all treatments (P>.05). Hay intake decreased significantly (P<.05) as soyhull intake increased, except for the increase from 5.0 lb to 7.5 lb of soyhull intake per head per day for which the decrease in hay consumption was not significant (P>.05). Mineral consumption was unaffected (P>.05) by level of soyhulls in the diet. Feed cost per cwt of gain decreased significantly (P<.01) with the addition of soyhulls to the diet at the 2.5 lb per head per day level. Although feed cost per pound of gain did not differ significantly (P>.05) among groups receiving 2.5, 5.0 and 7.5 lb of soyhulls per head per day, the trend did favor higher levels of soyhulls in the diet.

Steers that received 7.5 pounds of soyhulls per head per day had a slightly lower feed cost per cwt of gain, $30.42, than did the other treatment groups. As the price of soyhulls and hay vary this will result in changes in the feed cost per cwt of gain; however, with soyhulls priced at $100 per ton and hay at $50 per ton it appears that 7.5 pounds per head per day was the most economical level of soyhulls fed in this trial. This level of soyhull consumption was slightly more than one percent of their average body weight during the trial. During this trial an additional pen containing nine head of similar steers were fed hay and soyhulls free choice with an average soyhull consumption of 15.94 lb per head per day. No problems, such as bloat or other digestive disturbances, were noted with these steers during the trial.

The Bottom Line

The results of this study showed that increasing levels of soyhulls in the diet of steer feeder calves increased weight gains and decreased hay consumption. The addition of soyhulls to the diet at the 2.5 lb. per head per day level significantly decreased feed cost per cwt of gain. Feed cost per cwt of gain did not decrease significantly at higher levels of soyhulls in the diet, however, the trend did favor higher levels.

Level of Soyhulls Fed (lb/hd/d)
Item 0 2.5 5.0 7.5
No. of Head 20202020
Hay Intake, lb 19.78e 16.82f 14.83g 13.16g
Mineral Intake, oz 3.793.903.833.87
Starting Wt, lb592.20592.05588.45590.45
Ending Wt, lb772.90813.00836.20874.65
Gain, lb180.70220.95247.75284.20
Avg daily gain, lb1.61a 1.97 b2.21c2.54d
Feed/gain 10.9a8.7b8.0c7.3d
Cost of Soyhulls, $/hd 14.0028.0042.00
Feed Cost, $/hd62.8a68.79 b77.00c86.45d
Feed Cost, $/cwt gain 34.78a31.13 b31.10b30.42b
a,b,c,d means with different superscripts in a row differ, P<.01.
e,f,g means with different superscripts in a row differ, P<.05.

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Last modified September 1996.
Martha Hufham, Department of Animal Science.