Organic vs conventional dairy studies flawed, NZ review says

The differences between organic and conventional dairy aren’t quite as clear-cut as they might first appear, a New Zealand study says.

The researchers reviewed almost 200 publications, concluding that previous studies comparing the two have been largely ambiguous. This is due to the complexity of research questions and, most importantly, the range of variables and factors that influence milk composition.

“When comparing organic and conventional milk composition (especially milk fatty acids), previous studies have generally compared organic dairying with milk produced from grass-fed cows to conventional dairying with milk produced from concentrate-fed cows,” wrote lead author Dr Don Otter, senior scientist, food and bio-based products, AgResearch Grasslands Research Centre.

“The differences in milk composition observed are actually due to the different diets of the cows (ie, pasture versus concentrate feeding) rather than organic versus conventional farming systems.”

The researchers did not comment on whether consumers are willing to pay more for organic milk due to its perceived environmental and animal welfare benefits.

However, they do say that, because there are so many factors that affect milk composition, it is difficult to control for all of them when comparing organic to conventional milk production.

“The term ‘organic’ when applied to dairying is not universal and, to a large extent, is defined simply by regulations that differ from one country to the next. ‘Conventional’ is basically anything that is not ‘organic’,” the researchers wrote.

“However, in most parts of the world, conventional dairying is associated with high levels of grain feeding, the use of cow breeds which produce high milk volumes, and the application of large amounts of fertiliser (‘high input’ farming), while organic dairying is tied to pasture and forage feeding, lower amounts of fertiliser application, and the use of mixed or minority breeds (‘low input’).

“The vast majority of differences reported between organic and conventional milk come from what cows are fed and their breed, and is not anything unique to being organic or conventional in itself.”

The review was published in the Journal of Dairy Science.