#07-167

Complete

Date Full Report Received

08/24/2010

Date Abstract Report Received

08/24/2010

Investigation

Institution:
Primary Investigator:
Co-Investigators: M. Latour, A.P. Schinckel

The feeding of dried distillers grains with solubles (DDGS) is becoming a common place in the swine industry to help reduce feed costs. However, there can be reduced growth performance, carcass yields, and softer pork fat that causes processing issues when feeding high levels of DDGS. We investigated what a short (26 day) withdrawal of 20% DDGS prior to slaughter in combination with beef tallow (BT) or choice white grease (CWG) would do to grow-finish pig performance, carcass traits and bacon quality.

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.

The improved performance of pigs switching from a 20% DDGS diet to a corn-SBM or corn-SBM+5% fat (either BT or CWG) diet at the end of the grow-finish period offers some indication of the limitations that the 20% DDGS can have on pig performance. The removal of 20% DDGS from the pig diet 26 days prior to slaughter can completely recover the slight reductions in carcass weights and yields if the withdrawal diet contains added energy (5% added fat in this study). The withdrawal of DDGS from the diet was successful in reducing all carcass fat and loin depots IV values. A longer withdrawal period may be needed to have a greater impact on carcass IV values, depending on the amount carcass IV needs to reduced or changed to meet your processors target for acceptable pork fat quality. However, the feeding of 20% DDGS had only minor effects on the processing and cooking characteristics of thick cut bacon slices in this study.