HUGE variations in the nutritional value of milk has been identified in a new report
A survey by Newcastle University found organic milk to be more consistently nutritious than the average but also found similar differences between brands of ordinary milk.
The team which did the work will not name the poorer-value brands but will take its findings to the dairies which make them.
Research leader Gillian Butler said there were strong indications that the better milk came from the animals fed most grass and grass-based fodder.
It was hard to say for certain, because milk from all sorts of sources is invariably mixed. But the milk with the poorest scores also had high cell counts linked to mastitis and other indicators of intensive farming.
The discovery of significant variations in conventionally produced milk was one of a number of findings by the researchers.
It also stated that organic milk sold in supermarkets showed higher levels of nutritionally beneficial fatty acids as compared with non-organic milk, regardless of the time of year or weather conditions.
Researchers also found that wet weather had an effect on the quality of milk.