rBGH/rBST (Dairy Hormones)

Recombinant bovine growth hormone (rBGH/rBST) is injected into dairy cows to increase milk production by 10-15%. Monsanto (now Bayer) developed it; the FDA approved it in 1993. It's banned in the EU, Canada, Australia, New Zealand, and Japan due to animal welfare concerns (increased mastitis, lameness) and questions about elevated IGF-1 levels in milk. About 17% of US dairy cows receive rBST. The "rBST-free" label on milk exists because consumers demanded it so strongly that retailers like Walmart, Kroger, and Costco switched to rBST-free milk even without a ban. Market forces accomplished what regulation didn't.