Science - September 16, 2011

Earlier silaging improves milk quality

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Dairy farmers should silage their grass and maize earlier to raise the quality of milk produced, according to Nazir Khan, who has correlated the levels of healthy unsaturated fatty acids in milk with the fodder given to the cows.

The milk in our supermarkets has become less healthy over the last few decades because the proportion of unsaturated fats it contains has gone down. This partly through changes in fodder: cows get less fresh grass these days and more concentrated feed and baled fodder. And these feeds contain lower levels of unsaturated fatty acids. Khan researched the possibilities for raising the percentage of unsaturated fats in milk.  To this end he measured the fatty acid composition of grass and maize before and after silaging and the composition of the milk. The greener the grass and maize, the more unsaturated fats they contain, which end up in the milk. Farmers who silage their fodder should stop harvesting their grass at a late growth stage and should not dry the grass too long, because the healthy fatty acids oxidize during the drying process. Maize should be harvested for silaging earlier, too. Farmers would also be well advised to choose maize varieties that stay green longer, says Khan. Dutch dairy farmers are not currently rewarded financially for supplying milk rich in unsaturated fats to the factory. Nazir Khan's research was financed by his country, Pakistan. Nazir Ahmad Khan receives his PhD on 19 September from Wouter Hendriks, professor of Animal Nutrition.

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