Abdominal Fat Pad Reduction in Broilers with Thyroactive Iodinated Casein

Abstract Two experiments were conducted to determine the effectiveness of thyroactive iodinated casein (Protamone) in preventing excessive fat deposition in broilers and to determine the most practical level of protamone when considering growth, fat deposition, feed efficiency, and other characteristics. In Experiment 1, 128 commercial broiler chicks (Cobb Color Sex) were fed diets containing each of the following protamone levels: 0, 55, 100, 200, 500, and 1500 mg/kg. Based on the results of Experiment 1, the levels used in Trial 2 were: 0, 100, 200, and 400 mg protamone/kg feed. All birds were processed at 49 or 51 days of age in Experiment 1 and at 49 days in Experiment 2. A protamone level of 100 mg/kg decreased fat deposition without decreasing body weight. Higher levels caused further reductions in fat deposition but with some loss of body weight. Feathering at 2 weeks of age and water pickup during chilling were also improved by protamone. Protamone feeding also resulted in poorer feed conversion, greater shrink and dressing losses, and at the highest levels, increased mortality, lower carcass grade, and lower conformation scores. Protamone fed at low levels appears to have potential as a tool in reducing excess fat in broilers.