1999 at doses of 5–20mg/kg to improve feed efficiency and carcass leanness, “anecdotal reports suggested that RAC in- creased the rate of non-ambulatory (fatigued and injured) pigs at US packing plants. This led to the addition of a caution statement to the ‘Paylean’ label, and a series of research studies.”

Among other findings of further research, RAC was found to increase pig heart rate, cause tremors and, with aggressive handling, cause increased stress response at higher doses. In 2006, the accepted dosage range was changed in the US to 5–10mg/kg in market-weight pigs. Meanwhile, research continued. Some studies verified earlier results, while others demonstrated minimal effects on mortality, lameness and home pen behavior at various dose levels.

Meat safety Concerns related to animal welfare were also coupled with concerns over the safety of meat containing RAC (it is given to beef cattle and turkey as well as to pigs in some parts of the world). In 2012, the international standards agency Codex Alimentarius determined a safe maximum residue level (MRL) for human consumption, but the European Food Safety Au- thority (EFSA) found in 2009 that there was insufficient data to pinpoint this and has not changed its position since. For its part, the US Food & Drug Administration (FDA) has ruled in RAC’s favour. As explained by Thompson and his colleagues in a recent arti- cle, “In controlled safety and efficacy studies involving thou- sands of pigs, and a 20-year track record of safe use in hun- dreds of millions of finishing pigs, RAC has been shown to be a safe and effective feed supplement when administered at 5–10 ppm (4.5–9g/tonne feed) during the last 21–28 days, corresponding to the last 45–90 pounds [20–40 kg, ed.] of weight gain at finishing.” And, if RAC is fed in this manner, its MRL at slaughter will fall below the FDA MRLs for RAC of 15 ppb for meat and 50 ppb for liver. “The reason for this is that RAC is rapidly metabolised to inactive molecules,” Thompson and his colleagues explain, allowing “a zero-day withdrawal period in pigs, so producers can use the product safely right up to load-out.” In organ tissues, however, including liver, kidney and eyes, RAC accumulates to much higher levels and persists for a longer time. And while these parts of the pig are not typically eaten in North America, some of them are consumed in countries such as China.

Ractopamine ban in 160 countries As of 2014, the use of RAC was banned in 160 countries, in- cluding mainland China, Russia and those in the European Union (EU). Thompson and his colleagues note that the ze- ro-tolerance policy for RAC in China and the EU is also influ- enced by consumer safety events several years ago caused by improper use of clenbuterol, a molecule in the same

biochemical class (beta-agonists) as RAC. There were also concerns about “protecting their domestic pork industries from competition”. By banning imported pork from pigs ever fed RAC, no matter the amount fed or residue level in the meat, countries like China have also indirectly banned RAC use in pork-exporting countries, such as Canada and the US. (However, according to the National Pork Producers Council [NPPC] in the US, RAC is currently approved for use in nearly 30 nations, including Canada, and imports of pork from RAC-fed pigs are currently accepted by 75 countries.) For its part, while Canada has not banned RAC, its use in that country is non-existent. The Canadian Pork Council states that although RAC “poses no danger to human health”, because Canada is “the world’s third largest exporter of pork… Cana- da’s federally-inspected processing plants, which produce 97% of Canadian pork… require hogs that are RAC-free”. In addition, the Canadian Food Inspection Agency has a pro- gramme in which all Canadian pork exports are certified as originating from pigs never fed RAC. This initiative, the Cana- dian Ractopamine-Free Pork Certification Program, involves self-certification and random testing.

Stop feeding ractopamine In a similar move to protect export profitability, the major pork companies in the US have chosen to stop feeding RAC to pigs whose meat is bound for export. Way back in 2013, Smithfield Foods began phasing out RAC, and during the last two years others followed suit – JBS USA in October 2019 and Tyson Foods and Hormel Foods in early 2020. Taiwan had restricted the import of RAC pork but in August 2020, US trade officials successfully lobbied to have the re- striction eased. In September, Taiwan’s main opposition party began efforts to initiate a referendum opposing the govern- ment’s decision to lift the ban and, in November, it got con- tentious. Opposition party members dumped pig organs on the floor of parliament during a trade discussion, making in- ternational headlines. In the US, RAC had also been given to animals before they were taken to annual fair exhibitions, to build up and accen- tuate their musculature. In 2020, however, the Ohio State Fair (one of the largest in the US) stated that, “because RAC has been banned in international markets, swine exhibited at the 2020 Ohio State Fair are required to be RAC-free.” Other fairs have followed suit.

Residue levels While RAC seems to be impossible to use for export markets, some may wonder if producers who wish to gain the bene- fits of feeding RAC could stop feeding it to their pigs at a cer- tain point and achieve negative MRL test results (0.25 or less ppb RAC in meat), making it possible to export the meat to markets that allow only RAC-free pork.

▶ ALL ABOUT FEED | Volume 29, No. 5/6, 2021 27


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