Two trials that utilized 356 steers were conducted to evaluate the effects of
various fat sources (3.596 of ration dry matter) on performance and carcass traits of
finishing cattle fed flaked milo diets. In trial 1, soybean oil, bleachable tallow, and
yellow grease (blend of tallow and restaurant grease) were compared to a nonfat
control. Feeding fat increased (P<.05) daily gain, feed efficiency, carcass weight, and
dressing percent of steers. Soybean oil and yellow grease also tended to increase
12th rib backfat thickness and marbling. Feed costs of gain were improved only by
yellow grease. However, when increased carcass yield and quality were considered,
there was a significant economic return from all fat sources. In trial 2, fat
treatments were acidulated soybean soapstock (SBSS), tallow, a blend of 7096 SBSS:3096
tallow, and yellow grease. Feeding tallow or the SBSS: tallow blend improved (P<.05)
feed efficiency by 7.796 compared to the nonfat control. Pooled across source, feeding
fat increased (P<.10) backfat thickness and marbling. Compared to the control, feed
cost of gain was reduced 6 cents/l b by the SBSS:tallow blend. However, when
increased carcass value was accounted for, net returns of $3.50 to $6.00 per head
were seen for SBSS, tallow, and SBSS:tallow priced at 13, 17, and 13 cents per lb,
respectively. The SBSS:tallow blend provided greater performance than was predicted
by observed performance of steers fed SBSS or tallow separately, an indication of
associative response. In trial 2, intake and gain were lowest for yellow grease,
resulting in a negative economic return, which is in complete disagreement with results
obtained in trial 1.
