Effect of dietary distillers dried grains with solubles (DDGS) and pig removal strategy at harvest on the growth performance, carcass characteristics, and fat quality of growing-finishing pigs

The effect of increasing dietary level of distillers dried grains with solubles (DDGS) and pig removal strategy at harvest on growth performance, carcass characteristics, and fat quality of growing-finishing pigs was evaluated in a study carried out on a commercial wean-to-finish facility that used a total of 1,632 pigs housed in groups of 34. A randomized complete block design was used with 6 treatments/pig removal programs: 1) 0% DDGS; all pigs in pen taken off test and sent for harvest at one time (1 group); 2) 0% DDGS; all pigs in the pen taken off test and sent for harvest in 6 groups over time (6 groups); 3) 20% DDGS; 1 group; 4) 40% DDGS; 1 group; 5) 40% DDGS; 6 groups, and 6) 60% DDGS; 1 group. Diets were fed from 23.4 ± 1.15 kg to 128.9 ± 1.91 kg for pens sent for harvest as 1 group. For pens sent for harvest in 6 groups, the heaviest pigs were taken off test at a pen mean body weight of 112.1 ± 2.04 kg; subsequently, the heaviest pigs were taken off test every 7 days according to the following schedule: Week 1: Heaviest 10% of the pen, Week 2: Heaviest 20%, Week 3: Heaviest 20%, Week 4: Heaviest 20%, Week 5: Heaviest 10%, and Week 6: Lightest 20% of pen. At harvest, 1 barrow and 1 gilt/pen close to the pen mean were selected for detailed meat and fat quality evaluation (Subsample 1). An additional 1 barrow and 1 gilt/pen that were close to pen mean were selected for an additional gas chromatography fatty acid analysis (Subsample 2). Increasing DDGS inclusion level linearly reduced (P ≤ 0.001) average daily gain, feed intake, hot carcass weight, carcass yield, and last rib backfat thickness (measured on the carcass), but had no effect on feed efficiency and 10th rib backfat thickness (measured on the live animal using ultrasound). Iodine value increased (P ≤ 0.001) with increasing DDGS level for belly fat, jowl fat, and backfat (from 3rd thoracic vertebrae and clear plate). Average daily gain, feed efficiency, and 10th rib backfat thickness were lower (P ≤ 0.01) for pens of pigs taken off test and sent for harvest in 1 compared to 6 groups, however, feed intake was not affected (P ˃ 0.05) by pig removal strategy. Hot carcass weight and carcass yield were lower (P ≤ 0.001) for pens sent for harvest in 6 compared to 1 group. There was generally no effect (P ˃ 0.05) of pig removal strategy or sex on fat iodine value. These results suggest that increasing dietary levels of DDGS increases fat iodine value and decreases growth and carcass measures, however, sending pigs for harvest in 1 compared to 6 groups has generally no effect on fat quality