A total of 860 finishing pigs (PIC C48/L42×327; initially 66.2 kg BW) were used in a 76-d experiment to evaluate the effects of removing corn DDGS from diets at increasing intervals before harvest. Diets contained 40% DDGS prior to the experiment, 0 or 35% DDGS during the experiment from approximately 66 to 82 kg and 0 or 30% DDGS until the completion of the trial.
Pen served as the experimental unit, and there were 7 replicate pens/treatment with 23 to 25 pigs/pen. Pens were blocked by BW and allotted to 1 of 5 dietary treatments, differentiated by the number of days prior to slaughter that diets containing DDGS were withdrawn and replaced with corn-soybean meal-based diets. Withdrawal times were 76, 42, 27, 15, or 0 d (no withdrawal) before harvest. Linear and quadratic response to withdrawal time was evaluated using PROC GLIMMIX. For the overall period (d -76 to 0), as the time of DDGS withdrawal increased, ADG and final BW also increased (linear, P < 0.018) and G: F improved (quadratic, P = 0.019). Average daily feed intake quadratically decreased (P = 0.030) with increasing withdrawal time. There was a linear increase (P = 0.010) in HCW, with a marginally significant increase in carcass yield (linear, P = 0.094) with increasing DDGS withdrawal time. Loin depth and lean percentage did not demonstrate any evidence for treatment differences (P > 0.132). Backfat was linearly increased (P = 0.030) with increasing DDGS withdrawal time. Lastly, iodine value (IV) of belly fat was increased (linear, P = 0.001) with increased feeding duration of DDGS.
In conclusion, removing pigs from diets containing DDGS for longer periods before slaughter increased ADG and improved G:F, resulting in increased HCW. Belly fat IV was decreased as the length of DDGS withdrawal increased, with the highest IV resulting from pigs that consumed DDGS for the entire experimental period.