有机奶没有rbST，但测验结果表明与一般奶没有实质性区别。

http://www.nationaldairycouncil.org/SiteCollectionDocuments/child_nutrition/parenting_nutrition/OrganicMilkFAQ.pdf

A 2008 study in Journal of the American Dietetic Association analyzed the composition of organic milk, milk labeled "rbST-free" and regular milk, and found that the label claims were not related to any meaningful differences in milk composition.

What's the difference between organic farming and conventional farming?

Dairy farmers across the country are committed to producing high-quality milk and maintaining proper animal care and environmental practices on their farms. Conventional dairy producers use best management practices to ensure that dairy cows are healthy by providing them with comfortable living conditions, nutritious diets and good medical care. Organic dairy foods must additionally meet the requirements of USDA's National Organic Program. This includes using only organic fertilizers and pesticides, and not using rbST. Dairy foods can be labeled "USDA Organic" only if all of the additional criteria are met.