The number of US organic dairy cows increased from 2,265 in 1992 to 254,771 in 2011. Despite this rapid growth, organic herds are smaller than conventional herds, and produce approximately 30% less milk/cow (McBride and Greene, 2009). These discrepancies are explained by geographical location as well as management and nutrition. First, about 86% of organic dairies are located in the Northeast and Upper Midwest, which are characterized by herd sizes smaller than those from the West (McBride and Greene, 2009). Second, organic dairies must comply with the National Organic Program Pasture Rules, which mandate ruminants to consume at least 30% of their total DMI from pasture for a minimum of 120 d during the grazing season. Even though 95% of organic dairies use rotational grazing, they feed approximately 45% less grain than conventional dairies (Stiglbauer et al., 2013). Moreover, only 49% of WI organic dairies use corn silage (Hardie et al., 2014), and this figure is likely lower in other regions (e.g., Northeast). Thus, higher reliance on pasture and less grain and corn silage feeding limit metabolizable energy intake likely explaining the lower milk production in organic than conventional farms. Reduced milk production in organic dairies may be also associated with the low number of nonpasture feeds incorporated into lactation rations as well as the predominant use of component feeding in detriment of TMR. There is a growing interest among organic dairy farmers to feed lactating cows exclusively forage-based diets. In fact, organic milk processors (e.g., Organic Valley) are currently paying premiums for farmers shipping “grass-fed milk” in specific states (e.g., NY, PA, CA). In addition to reduced animal performance, the short- and long-term implications of no grain supplementation on animal health, BCS, and reproduction need to be addressed. Research should further address the effects on animal performance and health of feedstuffs commonly fed in organic dairies such as kelp meal, liquid molasses, and barley fodder, as well as the incorporation of alternative forage crops (e.g., small grains, millet, brassicas) as grazing options.