Friday, March 29, 2024

Spot the difference

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The differences between organic and “regular” milk products aren’t as straightforward to identify as some consumers might think when they pay the premium price for organic milk.
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In terms of nutrients, a New Zealand research team has found there is nothing to make organic milk distinctive from conventionally produced milk once the different factors that influence milk production are taken into consideration.If animal genetics, health, breed, diet, management or environment differs, then so will the composition of the milk produced.

The research team was led by Dr Don Otter, formerly a senior scientist with Food and Bio-based Products at AgResearch’s Grasslands Research Centre.

It reviewed almost 200 publications and found controlled studies investigating whether organic differed from conventionally produced milk had produced largely “ambiguous” results.

The main reason was the complexity of the research question and the number of factors and variables that could influence milk composition.

The review was published in the Journal of Dairy Science, the official journal of the United States Dairy Science Association.

Journal editor in chief and Missouri University, animal science, Professor Matt Lucy said the review presented “one of the most detailed treatises to date of organic versus conventional milk composition”.

Previous studies comparing organic and conventional milk composition, especially milk fatty acids, had generally compared organic dairying with milk produced from grass-fed cows to conventional dairying with milk produced from concentrate-fed cows.

But according to Otter’s team, the differences in milk composition observed in those comparisons resulted from what the cows were fed – pasture versus concentrate feeding – rather than the organic versus conventional farming systems.

The many factors that affected milk composition made it difficult to control for all of them when organic and conventional milk production were being compared, the review team said.

Moreover, the term “organic” had no universal meaning when applied to dairying.

Largely, it was defined by regulations that differed from one country to the next.

“Conventional” therefore was anything not “organic”.

But in most parts of the world, conventional dairying involved high levels of grain feeding, cow breeds that produced high milk volumes and the application of large amounts of fertiliser.

Organic dairying was tied to pasture and forage feeding, lower volumes of fertiliser and the use of mixed or minority breeds.

The review said the premium retail price for organic milk was based on perceptions that organic dairy farming was kinder to the environment, animals and people; that organic milk products were produced without the use of antibiotics, added hormones, synthetic chemicals and genetic modification; and that they might have potential benefits for human health.

Controlled studies investigating whether those differences were real had been largely equivocal.

One big complication was that farming practices and their effects differed depending on the country, the region, the year and the season between and within organic and conventional systems.

Factors influencing milk composition such as diet, breed and the stage of lactation had been studied individually while interactions between multiple factors were largely ignored.

Milk fatty acid composition has been a central research area when comparing organic and conventional milk, the review said.

The reason largely was the milk fatty acid profile responded rapidly and was very sensitive to changes in diet.

But farming practices (high-input v low-input) rather than farming system (organic v conventional) determined the milk fatty acid profile.

Similar results were seen between low-input organic and low-input conventional milks.

The researchers said studies, therefore, should consider factors other than the organic or conventional farming systems and how much they caused or contributed to the reported differences in milk composition.

Otherwise it was impossible to determine if there was a system-related difference between organic and conventional milk.

But the need to do that made it hard to develop an analytical method to distinguish organic from conventionally produced milk and provide product verification.

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