Impact of Ractopamine Hydrochloride (Paylean®) on Performance of Heavy Finishing Pigs Using a 3 Cut Marketing Strategy

The objective of this study was to evaluate growth and carcass performance of heavy finishing pigs fed ractopamine hydrochloride (RAC) (7.4mg/kg) in a 3-cut marketing strategy. Two thousand one hundred and fifty-eight pigs were utilized in 88 pens of approximately 25 pigs per pen in a commercial finishing barn. Sixteen percent of the total pig population were marketed during the first marketing period, 40% were marketed in the second marketing period, and the remaining 44% were marketed during the third marketing period. Data were analyzed as a randomized complete block design (blocking factor was d of start on test) with 2 treatments, and 44 replications per treatment. There were no differences (P = 0.98) in start weight between pigs fed RAC (121.00 kg) and pigs fed the control diet (120.99 kg). Overall, RAC carcasses (111.68 kg) were 3.92 kg heavier (P<0.0001) than the control (107.76 kg), carcass dressing percent was improved (P<0.0001) 0.67 (% points), loin depth was 4.95 % greater (P<0.0001), estimated lean was 0.99 percentage points greater (P<0.0001) (57.18 vs 56.19) and fat depth was 6.3% lower (P<0.0001) compared to the controls. Overall RAC pigs had 0.16 kg/d increased (P<0.0001) ADG (1.01 vs. 0.85 kg/d), and improved (P<0.0001) G:F (0.344 vs 0.278) while ADFI (2.96 vs 3.06 kg/d) was lower (P<0.0001) compared to control pigs. After the first 7 days of feeding, RAC pigs had increased (P < 0.0001) ADG (1.03 vs 0.72 kg/d) and improved (P<0.0001) G:F (0.359 vs 0.261) compared to control pigs. Loin depth increased (P < 0.01) and HCW from RAC carcasses tended (P=0.08) to be heavier than control carcasses (106.02 kg vs 104.41 kg). At the end of the second marketing period (21d), RAC carcasses were 4.46 kg (112.17 vs 107.71) heavier (P<0.0001), leaner (P<0.0001) and yielded more (P < 0.0001) than the control carcasses. RAC increased (P<0.0001) ADG, improved (P<0.0001) G:F and reduced (P<0.0002) ADFI compared to the controls. At the end of the third marketing period (35d), RAC carcasses were 4.15 kg (113.05 vs 108.9) heavier (P<0.0001), leaner (P<0.0001) and had greater (P<0.0001) dressing percent compared to the controls. RAC inclusion improved G:F (P < 0.0008) and reduced (P<0.0001) ADFI compared to the controls. These results suggest that while improvements in growth performance from feeding RAC will generally decline after 21 d of feeding, carcass traits, particularly carcass yield and lean content, will continue to improve until d 35.