Use of Ractopamine (PayleanŽ) in the Swine Industry: An Update

Livestock Update, January 2003

Chris Shumate and C. M. Wood, VA Tech

Ractopamine (RAC), marketed as Paylean®, is a small compound that binds to beta-adrenergic receptors in the body. It takes energy from fat growth and redirects it to promote the increase of muscle fiber diameter and the growth of lean muscle protein in the ham, belly, and shoulder. Ractopamine has been shown to increase hot carcass weight, dressing percent and loin eye area in pigs (Trapp et al., 2002), and can also reduce the number of days to market. The growth response is observed in many species, but RAC has only been officially approved for use in swine.

According to label directions, Paylean® should be included in the feed for the last 90 days before market. For a target weight of 240 lb, begin feeding Paylean® at 150 lb. Paylean® should be mixed in the feed at a rate of 4.5 to 18 g/ton of feed (5 to 20 ppm). According to Mills (2002), RAC response is rapid during the first week of use, but the results begin to diminish as the program extends from weeks four to six. When fed at the maximum rate (18g/ton), RAC can increase the amount of lean removed from the carcass from 51.8 to 57.5% (Schinckel et al., 2002), or almost 10.5 lb per animal.

Depending on the genetics of the swine, RAC can have varied results. A research project was conducted by Schinckel et al. (2002) to determine the efficacy of RAC in pigs with different rates of lean gain. The research suggests that while increased growth due to RAC can be seen in all pigs, the most dramatic increase can be seen in pigs that already have a greater genetic potential for lean growth and carcass lean percentage.

An important concern is whether the use of RAC will affect the quality of meat produced. Smith et al. (1995) showed higher pH values, lower cooking losses, and a darker color meat in gilts, but lower water holding capacity and a lighter color meat in boars. These results suggest RAC efficacy may be dependent on gender as well as genetic potential. Overall, the effects on pork quality were minimal in that study. More recent reports (Sterle et al., 2001), however, indicate that there may be an unfavorable interaction between the PSS gene and RAC.

A major concern being researched now is the effect of RAC use on the environment. In a study by Sutton et al. (2001), barrows were used to determine effects of RAC and CP level on N and P retention and excretion in urine and feces of finishing pigs. Average manure output was reduced by 3.9% in pigs fed RAC and N excretion can be reduced by 10.7 to 34.2%. In anaerobic storage of manure, RAC reduced levels of N, NH3 emissions, and volatile fatty acid production. Thus, the use of RAC can potentially reduce the amount of odor and increase the air quality of the surrounding environment.

Ractopamine has so far shown itself to be a product with numerous advantages and minimal negative effects. It has been shown to increase lean growth rate, reduce fat growth, shorten the time needed for a pig to reach market weight, and have a beneficial outcome on the environment. If properly incorporated into production, RAC can yield major benefits. With a cost of $30 to 40/ton of feed (at 18 g/ton), each producer must determine the optimal use of Paylean®. Optimal conditions consist of the level and duration of use, and depend on the amount of payment gained for the additional lean produced.

Literature Cited
Mills, S. E. 2002. Biological basis of the ractopamine response. J. Anim. Sci. 80(E. Suppl. 2): E28-E32.

Schinckel, A. P., B. T. Richert, and C. T. Herr. 2002. Variation in the response of multiple genetic populations of pigs to ractopamine. J. Anim. Sci. 80(E. Suppl. 2): E85-E89.

Smith, W. C., R. W. Purchas, A. Van Enkevort and G. Pearson. 1995. Effects of ractopamine on the growth of entire male and female pigs fed ad libitum or at a restricted level. New Zealand J. Agr. Res. 38:373-380.

Sterle, J. A., C. L. Skaggs, and D. B. Griffin. 2001. Frequency of the porcine stress gene in show pigs and its effects on meat quality. J. Anim. Sci. 79:(Suppl. 1):73 (Abstr.).

Sutton, A. L., B. T. Richert, S. L. Hankins, S. A. DeCamp and A. L. Carroll. 2001. Potential impact of ractopamine on environmental stewardship. Retrieved online 10/12/02. http://www.fass.org/fass01/pdfs/Sutton.pdf

Trapp, S. A., J. P. Rice, D. T. Kelly, A. Bundy, A. P. Schinckel, and B.T. Richert. 2002. Evaluation of four ractopamine use programs on pig growth and carcass characteristics. J. Anim. Sci. 80(suppl. 1): 104.

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