Volume 40 Number 4 Winter 1993

Ensiling Broiler Litter and Johnsongrass Forms Quality Feedstuff

B.J. Rude and D.L. Rankins, Jr.

Broiler litter and johnsongrass often are considered liabilities for Alabama agriculture. However AAES research has shown that the two can be combined to produce a palatable and nutritious feedstuff. Approximately two million tons of broiler litter (a combination of feed, manure, and bedding material that collects on the floor of broiler houses) are produced annually in Alabama alone. Though there are several uses for litter, such as applying it to land as a fertilizer or using it as an inexpensive protein source for beef cattle, additional uses for this by-product are needed.

Johnsongrass, which can be a noxious weed in row crops, grows abundantly in the state and is sometimes used as a forage. However, some of the nutritional value of the forage can be lost when it is baled for hay under Alabama's humid weather conditions.

An AAES study looked at ensiling broiler litter with johnsongrass, a method that would optimize the nutritional quality of the grass and also eliminate pathogenic organisms in the broiler litter, making it safe as a livestock feed.

For the AAES study, johnsongrass-broiler litter silage was compared to corn-broiler litter silage. Johnsongrass was harvested in early June at 65% moisture and ensiled with 10 or 20% added broiler litter (wet basis). Com was harvested in late July at 65% moisture and ensiled with broiler litter added at 10 or 20%. On a dry matter basis, these mixtures contained 18.5 and 37% litter. In mid-September, the silages were fed to growing lambs weighing an average of 64 pounds each.

The crude protein content and the mineral content of both corn and johnsongrass silages were enhanced by the addition of broiler litter (Table 1). Lignin and acid detergent fiber values were greater for the johnsongrass silages, as was the pH for these silages. This indicates that the johnsongrass mixes ensiled to a lesser extent than the corn mixes, probably because of the greater fiber content. However, the pH of all silages were less than or equal to 4.7, which indicates they were appropriately processed.

All four silages were readily consumed when offered to lambs. Average consumption was 2.25% of body weight. Digestibility values were acceptable for all silages (Table 2); however, johnsongrass silage with added broiler litter was less digestible than corn-broiler litter silage. Again, this was probably a result of johnsongrass being more fibrous than the corn forage. Stage of maturity at harvest influences the fiber content of forages. However, the johnsongrass was harvested at the boot stage, indicating that it would be difficult to obtain acceptable yields that would contain less fiber. Nonetheless, johnsongrass still produced acceptable digestibilities and was palatable. Addition of either 10 or 20% broiler litter had no effect on nutrient digestibilities. Addition of more than 20% litter would raise the pH above 4.7, which would be unacceptable.

By correlating the estimated nutrient requirement tables for beef cattle to these results with sheep, a few conclusions can be drawn. The johnsongrass silages were adequate in crude protein content for all types of cattle. However, the silages were lacking in energy content. Based on energy retention values in these sheep, a 600-pound steer would gain only 1 to 1.2 pounds per day. As a feedstuff for early-pregnant brood cows the johnsongrass silages would be nutritionally adequate. Corn silage yields typically are 10 to 15 tons per acre in Alabama. At 65% moisture, this equates to 3.5 to 5.25 tons of dry matter per acre. Johnsongrass will typically yield 2 to 5 tons of dry matter per acre. Because planting corn would be more costly than utilizing existing stands of johnsongrass, the economic benefits ofjohnsongrass are clear. Johnsongrass silage, although not equal to the corn silage, was acceptable and when economic factors are considered, it offers a viable alternative for ensiling broiler litter.

Rude is Graduate Research Assistant and Rankins is Assistant Professor of Animal and Dairy Sciences.

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