Organic milk is gaining share as a percentage of total milk volume across a number of retail channels, including supermarkets, according to a report from MilkPEP based on research from Prime Consulting Group, Bannockburn, Ill. As total milk volume is declining — it fell about 1.7% in 2011, according to the report — organic volume rose over 15%, to 240.7 million gallons. Club stores saw a significant portion of that growth in volume, with sales up 57% over 2010 levels. About 10% of milk sold in club stores is organic, the report stated. Natural food stores have the highest percentage of organic milk volume, accounting for more than half of the 29.7 million total gallons of all milk sold in that channel in 2011. Traditional supermarkets also saw increases in organic milk sales last year, although the channel’s share of total milk volume decreased by more than a full percentage point, to 42.8% in 2011, down from 43.9% in 2010.