Bad weather means poorer milk, research claims

by Natalie Evans. Published Mon 17 Jan 2011 10:19

Wet summers and cold winters have led to cows producing milk that is lacking in vital nutrients but high in saturated fat, scientists are warning.

University researchers found that milk produced after a run of adverse weather contains lower levels of beneficial fatty acids compared to that collected during 'normal' spells.

Scientists at the University of Newcastle discovered that following wet, cool summers and harsh winters, the standard milk on sale was higher in saturated fat and lacking in beneficial nutrients.

However, simultaneous tests on organic supermarket milk showed higher levels of beneficial fatty acids compared with 'ordinary' milk, regardless of the time of year or weather conditions.

The study, published in January's 'Journal of Dairy Science', stems from research conducted in 2007 into the difference between organic and conventional milk at its source on farms.

Gillian Butler, who led the study, said: "We wanted to check if what we found on farms also applies to milk available in the shops.

"Surprisingly, the differences between organic and conventional milk were even more marked.

"Whereas on the farms the benefits of organic milk were proved in the summer but not the winter, in the supermarkets organic milk is of significantly better quality year round."

During the study, higher levels of rainfall and lower temperatures were found to affect cows' behaviour, reducing grazing intake and milk output.

Famers were also forced to increase supplementation with concentrated feeds or conserved forage to maintain milk yields in these conditions.

There was a considerable difference between the milk bought in the first sampling period, between July 2006 and January 2007 and corresponding times a year later.

The second set of samples, following a particularly wet summer in 2007, was higher in saturated fat and lower in beneficial fatty acids.

Gillian added: "We didn't expect to find differences between the sampling period but this is likely to be down to the impact of the weather on availability and quality of forage.

"If these weather patterns continue, both forage and dairy management will have to adapt to maintain current milk quality.

"Switching to organic milk provides a natural way to increase our intake of nutritionally desirable fatty acids, vitamins and antioxidants without increasing our intake of less desirable fatty acids.

"By choosing organic milk you can cut saturated fats by 30-50 percent and still get the same intake of beneficial fatty acids.

"The omega-3 levels are higher but omega-6 is not, which helps to improve the crucial ratio between the two."

The research, conducted by the university's Nafferton Ecological Farming Group and its Human Nutrition Centre, has been described as "groundbreaking" by the Soil Association.

Head of policy, Emma Hockridge, said: "This groundbreaking research proves for the first time that people buying organic milk will be benefitting from the higher levels of beneficial fatty acids through the whole year."

The Dairy Council said it would study the detail of the report before commenting.

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