A total of 288 pigs (PIC 327 × 1050, initially 107.0 lb BW) were used in an 87-d trial
to determine the effects of diet form and corn oil on growth performance, carcass
yield, and iodine value (IV) of growing-finishing pigs. Treatments were arranged in a
2 × 3 factorial with the main effects of diet form and oil source. The 2 diet forms were
meal or pellet. The 3 dietary formulations were: (1) corn-soybean meal–based control,
(2) control with 30% dried distillers grains with solubles (DDGS) and 19% wheat
middlings, and (3) control with 3% corn oil.
No diet form × diet formulation interactions were observed for growth performance,
HCW, or carcass yield. Overall (d 0 to 87), pigs fed pelleted diets had increased
(P < 0.05) ADG, decreased (P < 0.05) ADFI, and improved (P < 0.05) F/G compared
with pigs fed meal diets. Diet form did not influence HCW or carcass yield. Pigs fed
diets containing DDGS and wheat middlings had decreased (P < 0.05) ADG compared
with pigs fed the control or corn oil diets. Feeding the corn oil diet resulted in decreased
(P < 0.05) ADFI compared with pigs fed the diet with DDGS and wheat middlings,
with pigs fed the control diet intermediate. Feed efficiency followed dietary energy, with
pigs fed the corn oil diet having the best (P < 0.05) F/G, pigs fed DDGS and wheat
middlings diet having the worst, and pigs fed the control intermediate. Pigs fed the diet
with DDGS and wheat middlings had decreased (P < 0.05) HCW and carcass yield
compared with pigs fed the control or corn oil treatments.
No interaction was detected between diet form and oil source for belly fat IV. Pigs fed
pelleted diets had increased (P < 0.05) belly fat IV compared with those fed meal diets,
regardless of diet formulation. Belly fat IV was greatest (P < 0.05) for pigs fed DDGS and
wheat middlings, lowest for pigs fed the control, and intermediate for pigs fed the corn oil
diets. An interactive effect between diet form and oil source was detected (P < 0.05) for
shoulder fat IV, caused by an increase in shoulder fat IV from feeding pelleted diets for
the control or corn oil treatments. Thus, with the exception of the lack of increase in IV
in pigs fed the pelleted DDGS and wheat middlings diet, feeding pelleted diets increased
carcass fat IV. Furthermore, we found no evidence that the source of fat (endogenous vs.
supplemental) in pelleted diets affected the IV response to pelleting.
