Effect of feeding distillers dried grains with solubles and conjugated linoleic acid on growth performance, carcass characteristics, and fat quality in finishing pigs

Abstract Text: The effect of feeding conjugated linoleic acid (CLA) and distillers dried grains with solubles (DDGS) on growth performance and carcass and fat quality was evaluated in a study performed under commercial conditions. The study started at a BW of 92.2 ± 1.20 kg and ended after 70 d. A RCBD with 15 treatments that involved all combinations of 3 DDGS levels (0% DDGS, 30% DDGS, and 30% for 42 d followed by 0% for the last 28 d of the study), 3 CLA levels (0, 0.5, and 1.0%), and 3 CLA Feeding Durations (0, 14, and 28 d prior to harvest) was used. The CLA product used contained 60% of CLA isomers. There were 11 pens of 20 pigs/treatment and 3,300 total pigs on the study. At the end of the growth period, pigs were sent for harvest at a commercial plant. Belly quality measurements were collected 24 h after harvest; iodine value (IV) was measured on a sample of backfat from the clear plate using near-infrared spectroscopy. All data meeting the criteria for normality were analyzed using the PROC MIXED procedure of SAS (SAS Inst. Inc., Cary, NC).  Including 30% compared to 0% DDGS in the diet reduced (P<0.05) ADG and G:F by approximately 4%, carcass yield by approximately 0.6 percentage units, belly firmness by 1 point, and increased (P<0.05) IV by on average 7.4 g/100 g (68.9 to 76.3). Withdrawing DDGS from the diet for the last 28 d increased (P<0.05) ADG by approximately 2%, G:F by approximately 3%, carcass yield by approximately 0.5 percentage units, belly firmness by 0.5 points, and reduced (P<0.05) IV by 3.6 g/100 g (76.34 to 72.73) compared to feeding 30% DDGS throughout the study. Feeding CLA had no effect (P>0.05) on growth performance; however, feeding diets with 1% CLA for 28 d increased flop distance (P=0.02) by 1.1 cm, and subjective firmness score (P=0.004) by 0.2 points. Including CLA at either 0.5 or 1.0% reduced (P<0.05) IV by 1.4 and 1.7 g/100 g, respectively, and including CLA in the diet for either 14 or 28 d reduced iodine value (P<0.05) by 1.1 and 2.0 g/100 g, respectively, compared to controls (0% CLA). The results of this study suggest that feeding DDGS reduced growth performance, carcass yield, and fat firmness and withdrawing DDGS from the diet 4 wk before harvest and/or feeding CLA can improve fat firmness.

Keywords: CLA, DDGS, fat quality