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 iodinevalue. When the fats were incorporated into corn-andsoybean-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.