Metal Residues in Tissues, Animal Performance and Carcass Quality with Beef Steers Grazing Pensacola Bahiagrass Pastures Treated with Liquid Digested Sludge

Abstract

Forty-eight beef steers were randomly allotted to three Pensacola bahiagrass pastures, two of which were treated with liquid digested sludge (LDS). The animals grazed the pastures for 168 days, and the effects of the treatments on concentrations of selected potentially toxic metals in tissues (liver, muscle and kidney), animal performance and carcass quality were determined. The experimental treatments were (1) control — normal fertilization; (2) LDS 1 – 7.6 cm LDS/ha (16 metric tons sludge solids/ha), and (3) LDS 2 – 15.2 cm LDS/ha (32 metric tons sludge solids/ha). Estimates of sludge content of the grazed forages, on a dry matter basis, were 2.21 and 4.74% for the LDS 1 and LDS 2 pastures, respectively. Cu concentrations in the liver were lower (P<.01) for steers grazing the LDS pastures. There were no differences between treatment groups in the concentrations of selected metals in muscle tissues. The concentrations of metals in the liver, muscle and kidney were below tolerable levels established for fish or other food products. Significant differences existed between treatment groups in fecal concentrations of the metals. Metal concentrations in fecal material increased as the level of LDS applied to pasture increased. There were no differences due to treatment in any of the animal performance and carcass characteristics.