That is not possible, according to Iowa State University veteri- narians Dr Locke Karriker and Dr Chris Rademacher. They note in a recent RAC factsheet that “Unfortunately, there is not a study that directly measures this [but] at a minimum, RAC can be detected for 42 days after the end of feeding… so, it is likely that most or all benefit of feeding RAC would be lost by the time that the pig tested negative.”

Ractopamine hydrochloride has been shown to be a safe and effective feed supplement when adminis- tered at 5–10 ppm

during the last 21–28 days.

Other options Are there other feed ingredients that result in lean mass in- crease in the way RAC does? Yes, perhaps at least two. Because safflower oil in animal diets has resulted in increased lean mass and decreased body fat, scientists at the University Federal do Rio Grande do Norte in Brazil recently compared it in pig diets to RAC. (They also included coconut oil, which has a similar fatty acid profile to safflower oil.) In the results pub- lished in April 2020, the scientists found that all three addi- tives in finishing pig diets had a “significant effect on weight gain and feed conversion” and that both oils “can be used as substitutes for RAC”. However, Thompson notes that while these results are “inter- esting”, the trials “were grossly under-powered to draw any conclusions regarding the impacts of these agents on any key performance indicator used in pork production. Had they used six pens with 12 animals per pen, instead of one animal, they might have had an adequate study.” None of the NPPC, National Pork Board or animal health com- panies Elanco (the firm that makes Paylean) or Zoetis had comments about alternatives to RAC.

Other uses for RAC Although RAC can be perceived as unhealthy for humans and pigs, it may have potential to improve human health.

However, further investigation may be difficult. In December 2020, Dr Frank Fan, a researcher, doctor and superintendent at Taitung Hospital in Taiwan, published a paper in which he hypothesises, based on lab experiments and epidemiological studies, that consuming meat containing RAC residue could be a viable way to lower the incidence of Parkinson’s disease. In his paper, Fan explains that Parkinson’s is “estimated to be the fastest-growing neurodegenerative disease in the world”, and notes that after South Korea lifted the ban on US beef imports containing RAC residues in 2008, the incidence of Parkinson’s disease decreased in that country “significantly” four to seven years afterwards. When asked if, theoretically, a very low dose of RAC alone might be used in a clinical trial instead of meat with RAC resi- dues, Dr Fan says he doesn’t think such a trial would be ap- proved. One reason for this is RAC’s “potential adverse effects on the cardiovascular system, especially for elderly people”. In addition, Dr Fan says that “although it has been concluded that RAC has no carcinogenic and genotoxic effects on animals or human beings”, he has outlined in another new paper that “RAC might bring negative influence on patients who already have cancer cells in their bodies”. He says, “Accordingly, I would not support an RAC trial for prevention of Parkinson’s disease.”

Extent of use, now and in future Numbers related to the use of RAC are not easy to come by. It is still used in many countries but extent of use and whether use is decreasing is not clear in terms of numbers of pigs. Right now in the US, consumers can buy either RAC pork or RAC-free pork (which has its own US Department of Agricul- ture label). As Jaydee Hanson, policy director at the Center for Food Safety in the US, explains, RAC-free pork can be more expensive but not necessarily; a large specialty grocery chain called Whole Foods offers them at the same price. As to whether RAC meat is safe, Hanson says that “out of an abun- dance of caution”, he would not recommend that anyone with a heart problem consume it. Looking forward, Hanson expects that the US pork industry as a whole will keep pushing for continued use of RAC as it al- lows for cheaper lean pork production, and that this feed ad- ditive will continue to be a topic of conversation, at least in the US. However, Hanson suggests that because the biggest pork-producing companies in the US are not using much RAC, usage may decrease. When asked for the NPPC perspec- tive on current and future extent of RAC use, communications director Rachel Gantz explains that “although RAC use by US hog farmers is not widespread, it is an option that is safe and acceptable. NPPC will continue to defend the right of US hog farmers to use production processes and products that are safe. NPPC opposes government mandates that, with no sci- entific backing, dictate production practices, unnecessarily increase food prices and inhibit consumer choice.”

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


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