Science - September 22, 2005

Milk from cows in field healthier

The claim that milk from pasture cows is healthier than milk from cows kept indoors is true. Research done at Wageningen University shows that the milk from cows that graze outside has a significantly higher percentage of unsaturated fatty acids.

Dr Anjo Elgersma of the Crop and Weed Ecology Group, together with researchers from other institutes including NIZO food research, tested hundreds of milk samples from test farms and dairy farms. The milk from cows that graze outside had an unsaturated fatty acid content of forty-five percent. The proportion of unsaturated fatty acid in the milk of cows that eat ensiled grass is lower: thirty percent.

Elgersma: ‘This is the first time that a distinction has been made between unsaturated and saturated fatty acids when measuring milk quality. In this respect the milk from outside cows is certainly healthier. The trend of keeping cows inside, as is happening more and more often in the Netherlands, is not a favourable development.’ Saturated fats increase the risk of heart and circulatory diseases.

When it comes to milk the Netherlands is not in the same league as New Zealand and Ireland, where the cows eat fresh grass outside nearly all the year round and therefore produce milk with a high proportion of unsaturated fats. But it is perfectly possible to keep cows outside for a large part of the year in the Netherlands. It’s not too hot or too cold, and the regular rainfall means that grass grows well. Cows grazing outside consume more unsaturated fatty acids because they eat more of the tips of the blades of grass, which contain relatively high amounts of these fatty acids.

The research is part of the project entitled ‘White engine on green fuel’, financed by Stichting AKK. Participants include the Animal Production Systems Group, the Research Institute for Animal Husbandry and LEI (Netherlands Institute for Agricultural Economics). The results of the research have been published in a number of journals including Animal Feed Science and Technology. / HB