Volume 38 Number 3 Fall 1992

On-Farm Processing Preserves the Nutritive Value of Broiler Litter

D.L. Rankins, Jr, J.T. Eason T.A. McCaskey and A.H. Stephenson

BROILER litter has been used as an economical feed ingredient for beef cattle for several years, providing an alternative disposal method for this by-product of the poultry industry. However, broiler litter must be managed properly to ensure it is a safe and valuable feedstuff for cattle. Research-developed techniques are providing new information on the best management practices for this resource.

Typical on-farm techniques for handling and processing litter include deep-stacking, which generates heat and eliminates potential pathogens. However, deep-stacking also can result in excessive heat generation within the stack, which binds the nitrogen and limits the nutritive value of the litter as a cattle feed. A recent Alabama Agricultural Experiment Station study at the Sand Mountain Substation, Crossville, evaluated the nutritive value of broiler litter deep-stacked in three different ways.

Approximately 20 tons of broiler litter were placed into each of three open-faced bays and deep-stacked to a height of approximately 6 ft. One stack was left uncovered, another was covered with 6-mil plastic, and the third stack was misted with water to form a 1-in. crust upon drying. After 30 days, the litter was used to formulate six experimental diets representing 25 and 50% litter from each of the three treatments. A control diet using urea and no litter also was formulated. All diets contained 10% cottonseed hulls, 2% limestone, vitamin A, and variable amounts of cracked corn.

Twelve crossbred, medium-framed steers averaging 451 lb. were assigned to each diet (six steers per pen and two pens per diet). Steers were weighed every 28 days throughout the study. Following 84 days on feed, three steers from each treatment were fed in individual pens and manure was collected from each steer so that nutrient digestibilities could be determined.

Within 28 days, four to eight steers being offered litter-containing diets were bloated. Therefore, poloxalene (a bloat preventative) was added to the diets for the remainder of the study. Steers consuming the control diet gained from 0.5 to 1.4 lb. per day faster than those consuming the litter-based diets, see table.

The deep-stacking method had no appreciable effect on steer average daily gains. Daily feed intake was not significantly different among cattle fed the experimental diets. Feed efficiency values followed the same pattern as daily gains; best for steers fed the control diet, followed by those fed 25% litter, and then those fed 50% litter. The suppressed weight gains as a result of the addition of broiler litter were directly related to the energy content of the diets. Broiler litter contained less energy than corn. However, the cost per pound of gain was quite similar among the seven treatments, see table.

Inclusion of broiler litter into the ration resulted in decreased digestibility of all nutrients except the fiber component (neutral detergent fiber). The deep-stacking method had no effect on dry matter, organic matter, fiber, or energy digestibilities. However, deep-stacking affected nitrogen digestibility. Nitrogen digestibility of diets containing plastic-covered litter was not different from the urea control diet, but was greater than for treatments containing uncovered or watered litter. Differences in nitrogen digestibility probably occurred because heating formed indigestible nitrogen complexes. The uncovered stack reached an internal temperature of 158 F, the watered stack 154 F, and the covered stack did not exceed 142 F.

Based on these findings, the temperature range between 142 F and 158 F appears to be very important for maintaining adequate availability of broiler litter nitrogen for cattle. The suppression of temperature caused by covering the stack resulted in a diet that contained 20% more digestible nitrogen. Previous research has shown that temperatures of 1420F for several days are adequate for the elimination of most enteric bacteria that might be associated with broiler litter.

In summary, steers fed the urea control diet gained extremely well. Incorporation of 25 and 50% broiler litter into the diets reduced weight gains and resulted in less efficient gains as a result of the decreased amount of dietary energy. However, the cost of each diet ranged from $0.282 to $0.305 per pound of gain. Covering the deep-stacked litter with plastic did not increase average daily gains, but did increase nitrogen digestibility, making it most useful in cattle with higher protein requirements, such as lightweight heifers. In some cases, uncovered stacks might achieve even higher temperatures, further accentuating these differences.

Rankins is Assistant Professor of Animal and Dairy Sciences; Eason is Superintendent, Sand Mountain Substation; McCaskey is Professor and Stephenson is former Research Associate of Animal and Dairy Sciences.

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