Impact of ractopamine hydrochloride on growth, efficiency, and carcass traits of finishing pigs in a three-phase marketing strategy

The objectives were to determine the effects of ractopamine hydrochloride (RAC) in a 3-phase marketing strategy. One thousand seven hundred forty pigs were used in 80 single-sex pens in 2 blocks. Each pen housed approximately 22 pigs. Sixteen percent of the total population of pigs was sold during the first marketing period, 18% was sold during the second marketing period, and the remaining 66% was sold during the third marketing period. Data were analyzed as a randomized complete block design of 2 treatments. Pigs in the second marketing group had greater growth performance indicators than pigs in the first marketing group. Over the entire feeding period, pigs fed RAC were 2.73 kg heavier (P < 0.0001), had 0.11 kg/d greater (P < 0.0001) ADG, and had 0.04 greater (P < 0.0001) G:F than pigs not fed RAC. Hot carcass weights were 3.3% greater (P < 0.0001), carcass yields were 0.68 (% units) greater (P < 0.0001), fat depth was 7.2% less (P < 0.0001), loin depth was 5.6% greater (P < 0.0001), and estimated carcass lean was 0.97% units greater (P < 0.0001) in RAC-fed pigs when compared with pigs not fed RAC. By the end of the first marketing period carcasses from pigs fed RAC (89.73 kg) were 2.1% heavier (P = 0.04) and gained 0.19 kg/d more (P = 0.03) carcass weight than carcasses from pigs not fed RAC (87.89 kg). By the end of the second marketing period carcasses from pigs fed RAC (99.00 kg) were 3.1% heavier (P < 0.001) and gained 0.14 kg/d more (P < 0.001) carcass weight than carcasses from pigs not fed RAC (96.02 kg). By the end of the third marketing period carcasses from pigs fed RAC (102.75 kg) were 3.7% heavier (P < 0.0001) and gained 0.10 kg/d more (P < 0.0001) carcass weight than carcasses from pigs not fed RAC (99.06 kg). Although carcass gain per day decreased with extended RAC feeding duration, HCW advantages continued to increase as feeding duration was increased from 7 d to 35 d. Growth benefits were evident during the initial marketing period, but as duration increased differences diminished. Therefore, RAC can provide the expected growth performance benefits when included in the diet for up to 21 d, but HCW advantages continue to increase throughout the entire 35 d feeding period. Even though carcass benefits were not as evident in pigs sold during the first marketing period, advantages (particularly HCW) continued to increase with each marketing period.