A comparison of eight grades of fat as broiler feed ingredients

Seven samples of feed- or pet food-grade fats (feed- and pet food-grade poultry greases, restaurant grease, white grease, animal/vegetable oil blend, palm oil, yellow grease) and one food-grade edible fat (soybean oil) were evaluated for quality and fatty acid composition. Active oxygen method (AOM) stability at 20 h ranged from 2 to 370 meq/kg; iodine value from 78 to 130 g/100 g; total moisture, insolubles, and unsaponifiables from 0.46 to 3.33%; initial peroxide values from 0.2 to 18.4 meq/kg; and free fatty acids from 0.08 to 21.0%. The ME of the fats ranged from 7.1 to 12.7 kcal/g and was positively correlated with AOM stability and iodine value. When the fats were incorporated into corn-and-soybean-meal-based diets at 3 or 6%, no differences in live performance due to fat source were observed. Increasing fat level from 3 to 6% decreased feed conversion by 3.4 points (1.628 vs. 1.662 g/g). Feeding feed-grade poultry grease resulted in significantly smaller abdominal fat pads compared to the other fat sources. Only moisture, insolubles, unsaponifiables, and free fatty acids were significantly correlated with performance responses. Differences were noticed in abdominal fat pad color (lightness and redness) due to fat source. Differences in MEn were not reflected in differences in bird performance.