Evaluation of Dairy Wastewater Solids as a Feed Ingredient

Samples of dairy wastewater solids from a milk processing plant were analyzed to determine variability in composition. Feed value of diets containing solids was evaluated by feeding sheep and swine the following: control diet (common feeds), control plus 5% dairy waste solids, control plus 10% solids, control plus 20% solids, or control supplemented with Ca and P. Dairy waste solids contained (on a dry basis) enough protein (35%), Ca (14%), P (2%), and Mg (.4%) to be useful as a feed ingredient, but concentrations varied. Feed intake, water intake, and weight gains of sheep and swine fed the 5% diet were similar to controls. Gains were lower and water intake higher for animals receiving the 10% and 20% diets than controls. Lower gains were not due to high mineral content per se, because gains for animals fed the mineral supplemented diet were similar to controls. Decreased gains may have been due to lower palatability or lower feed value of the 10 and 20% diets. Blood parameters were unaffected by diets, and there were no apparent health problems. Feeding diets containing 5% dairy waste solids to sheep and swine (and presumably cattle) is an alternative means of disposal.