In swine, ractopamine is correlated with adverse effects, especially hyperactivity, trembling, and broken limbs, leading to censure by animal rights groups.
In a conversation with Boulder Weekly newspaper, Colorado State University Professor of Animal Science Temple Grandin, an expert on animal welfare, described harmful effects of ractopamine on feedlot animals, such as cattle with stiff, sore, and lame limbs, and increased heat stress. In the same column, she also opines that meat from ractopamine-treated animals may be tougher.
Ractopamine use is a factor in the incidence of downer pigs, animals that are unable to move or stand.