Review: Effects of Ractopamine Hydrochloride (Paylean) on welfare indicators for market weight pigs
Johnson, A. K.
Benjamin, M. E.
Carr, S. N.
Salak-Johnson, J. L.
Thomson, D. U.
Calvo-Lorenzo, M. S.
This review summarizes the effects of ractopamine hydrochloride (RAC) dose (5, 7.5, 10, and 20 mg/kg) on market weight pig welfare indicators. Ractopamine hydrochloride (trade name Paylean) is a β-adrenergic agonist that was initially approved in the U.S. in 1999 at doses of 5 to 20 mg/kg to improve feed efficiency and carcass leanness. However, anecdotal reports suggested that RAC increased the rate of non-ambulatory (fatigued and injured) pigs at U.S. packing plants. This led to the addition of a caution statement to the Paylean label, and a series of research studies investigating the effects of RAC on pig welfare. Early research indicated that: (1) regardless of RAC administration, fatigued (non-ambulatory, non-injured) pigs are in a state of metabolic acidosis; (2) aggressive handling increases stress responsiveness at 20 mg/kg RAC, while 5 mg/kg reduces stress responsiveness to aggressive handling. Given this information, dosage range for Paylean was changed in 2006 to 5 to 10 mg/kg in market weight pigs. Subsequent research on RAC demonstrated that: (1) RAC has minimal effects on mortality, lameness, and home pen behavior; (2) RAC fed pigs demonstrated inconsistent prevalence and intensity of aggressive behaviors; (3) RAC fed pigs may be more difficult to handle at doses above 5 mg/kg; and (4) RAC fed pigs may have increased stress responsiveness and higher rates of non-ambulatory pigs when subjected to aggressive handling, especially when 20 mg/kg of RAC is fed.
This article is published as Ritter, M. J., A. K. Johnson, M. E. Benjamin, S. N. Carr, M. Ellis, L. Faucitano, T. Grandin et al. "Effects of Ractopamine Hydrochloride (Paylean) on welfare indicators for market weight pigs." Translational Animal Science 1, no. 4 (2017): 533-558. doi: 10.2527/tas2017.0060. Posted with permission.