At day 77 of the experiment, some pig’s diets were switched from 20% DDGS to corn-SBM control or a corn-SBM control +5% BT or +5% CWG to evaluate their impact on final pork quality when fed at the end of the grow-finish period (last 26 days prior to slaughter). Pigs that stayed on the 20% DDGS diet throughout the GF period were nearly 9 lb lighter than the Corn-SBM control pigs at the end of the grow-finish period. Pigs that switched from the 20% DDGS diet to being fed the Control+5% BT diet the last 26 days prior to slaughter had 18% greater ADG than pigs fed the 20% DDGS diet during this phase (1.90 lb/d vs. 2.25 lb/d). Also pigs fed the Control+5% BT and the Control+5% CWG diets had 20% better feed efficiency (G:F) than the pigs fed the 20% DDGS diet during these final 4 weeks premarket (0.30 vs. 0.25). Carcass weights were reduced by 8.5 lb when pigs were fed 20% DDGS throughout the grow-finish period compared to the corn-soy control pigs. The 26 day preslaughter removal of the DDGS and supplementing with either 5% fat sources in the corn-soy diet during this preslaughter period restored carcass weights to that of the corn-soy control pigs. Hot carcass yield was 1.7% less for pigs fed 20% DDGS throughout the grow-finish period (d 0-103) than corn-soy control pigs (77.3 vs. 75.6%). When pigs were fed 5% fat with the 20% DDGS followed by a corn-soy diet with 5% fat prior to slaughter also increased the carcass yield 1.8% over pigs fed 20% DDGS throughout the grow-finish period (P<0.05). There were no differences in 10th rib backfat or loin eye area among treatments leading to similar percent leans.
Feeding corn-SBM control in comparison to 20% DDGS throughout the grow-finish period impacted the fatty acid concentrations of the backfat layers, belly and to a lesser extent the loin. In all cases, concentrations of saturated fatty acids were less and unsaturated fatty acids, especially linoleic (18:2n6), increased for pigs fed 20% DDGS compared to the control corn-SBM control diet throughout grow-finish. Belly and backfat iodine values increased 8-10 units when pigs were fed 20% DDGS. The 26 day withdrawal of DDGS only partially recovered fat iodine values by 1-4 units depending on supplemental fat source inclusion, with the greatest response due to switching to a corn-soy+5% beef tallow diet preslaughter. Feeding 20% DDGs for any amount of time preslaughter tended to reduce bacon slice cracks but increased bacon slice webbing. Bacon slice cooking losses were 19% greater when pigs were fed 20% DDGS+5% fat followed by a corn-SBM +5% fat diet prior to market compared to corn-SBM control fed pigs.