Effect of corn dried distillers grains with solubles, conjugated linoleic acid, and ractopamine (paylean) on growth performance and fat characteristics of late finishing pigs

An experiment was performed to evaluate effects of dietary ractopamine, CLA, and corn distillers dried grains with solubles (DDGS) on growth and carcass and fat quality of finishing pigs. This study was conducted as a split-split plot arrangement in a generalized randomized block design. In total 1,102 crossbred barrows and gilts (initial BW = 100.4 kg, SD = 3.7 kg; pic 337 × c22) were randomly assigned to 1 of 8 dietary treatments that consisted of 2 diet sources [corn-soybean meal (corn-soy) and corn-soy + 20% DDGS], 2 levels of ractopamine (0 and 7.4 mg/kg), and 2 levels of CLA (0% and 0.6%). The pen was the experimental unit, with 6 replications per treatment for a total of 48 pens with 23 pigs per pen. Pigs had ad libitum access to water and feed during the 27-d experimental period. Ractopamine addition improved (p < 0.05) ADG and G:F over the control group. Furthermore, carcass weight, carcass yield, loin depth, and lean percentage were increased and back fat depth was decreased (p < 0.05) by feeding ractopamine. Feeding CLA resulted in improved (p < 0.05) ADG and G:F and increased lean percentage but reduced carcass yield (p < 0.05). The inclusion of DDGS did not affect ADG, adfi, or g:f but reduced (p < 0.05) carcass dressing percent. An increase (p < 0.05) in the concentration of pufa was observed with inclusion of DDGS, ractopamine, and CLA. Iodine value (iv) increased (p < 0.001) in both belly and jowl samples by feeding DDGS and ractopamine, whereas a decrease (p < 0.01) was observed when CLA was included in the diets. The fatty acid profiles of belly and jowl fat samples were affected (p < 0.05) by diet source × ractopamine, indicating that effects of dietary ractopamine depend on the fatty acid profile of the diet. These results indicate that feeding ractopamine and CLA could improve growth and carcass measures and that CLA was effective in diminishing some of the negative effects, especially on IV, caused by DDGS.