Previous feeding studies at NCSU have shown that soyhulls and wheat midds have about the same value as corn and soybean meal in both hay and silage-based diets. In a study with silage-based diets, however, both corn gluten feed and whole cottonseed depressed feed intake and gain, indicating that they may not be worth as much as their nutrient content would indi cate. The project reported here was designed to evaluate whole cottonseed, dried distillers' grains, and corn gluten feed, relative to corn and soybean meal in corn silage-based diets for stocker cattle.
On December 1st, 80 uniform steers were selected and assigned by breed to 8 groups (10 head per group.) Two groups were randomly assigned to each treatment, and cattle were housed in an open sided barn with concrete floor and outside lots. Calves were fed a total mixed ration each morning, and adequate feed bunk space was available in each pen for all animals to eat at one time. Gains were calculated from shrunk weights. Ingredient prices used were 26, 223, 121, 125, 178, and 148 $/ton for corn silage, soybean meal, corn, corn gluten feed, distillers grains and whole cottonseed, respectively. All diets con tained 76% silage and 24% concentrate (dry basis) and provided at least 200 mg lasalocid/head/day.
Total feed cost was lower for the three alternative concentrate diets than for the corn and soybean meal. Feed cost per unit of gain was also lower for distillers grains and cottonseed than for the corn and soybean meal. However, due to the markedly reduced perfor mance on the corn gluten feed diet, feed cost per unit of gain was higher than for corn and soybean meal. Fixed costs were figured at $28/calf over the feeding period. This includes the costs for equipment, death loss, labor, and other miscellaneous costs, and is a reasonable figure for a large stocker operation. It is important to include this in the economic analysis because fixed cost per unit of gain decreases as gains increase.
For the economic analysis, purchase price of the cattle was calculated to be $92.30/lb. This was calculated from the purchase price of the 4 cwt cattle plus all the costs of preconditioning divided by the starting weight. Sale price was calculated as the total price per head divided by the finishing weight ($83.20/cwt). Because the groups on byproduct feeds finished the trial somewhat lighter than the corn and soybean meal group a 2 $/cwt slide was used to determine value of each treatment group.
Net return after all costs on the cattle was similar for the corn and soybean meal, cottonseed and distillers' grains diets, but was lower for the corn gluten feed diet. Using a price slide greatly increased the net return on the corn gluten diet because the steers were 53 lb lighter than the control steers at the end of the trial. Based on the crude protein and energy values, the corn gluten feed, distillers grains and whole cottonseed should have been worth 148.00, 169.58 and 149.81 $/ton, respectively. Based on the net returns, the realized value, or the price we could have paid for the byproducts and still made as much profit as with corn and soybean meal, would have been 35.52, 138.69 and 134.60 $/ton for corn gluten feed, distillers grains and whole cottonseed, respectively.