21 November 1997


A SIGN of what may be in store for British dairy farmers comes from Denmark where a new law means that 20% of farmers will have to limit the amount of nitrogen excreted by their cows, reduce cow numbers, or buy more land.

Until this year, Danish farmers were allowed to spread the annual production of livestock manure from a maximum of 2.3 cows a ha (0.93/acre) on the land and 92% of farmers fell within the limit. Others spread manure on the farms of neighbours.

But new environmental regulations on limiting nitrogen spread on the land from animal manure means that, from the turn of the century, an animal unit will be defined as equal to 100kg of N/ha (80 units/acre). The amount produced by the animal at grazing has to be taken into the equation.

According to Ole Klejs Hansen from the cattle husbandry division of the Danish farm advisory service, the change would demand a reduction in stocking rates of about 16%.

"Cattle excretion of N has to be limited and dairy farmers must follow the example of pig producers. where they have reduced N excretion to such an extent that they will not be affected by the new law," he says.

The Danish government has permitted scope for adjustment of permitted N levels if the farmer grows crops which can absorb large quantities of N in the autumn and the advice from Dr Hansen is a mix of fodder beet, grass, and catch crops.

"Maize and whole-crop wheats do not count because they do not absorb large volumes of nitrogen in autumn," he says.

He calls for much more attention to reduced N intake and increased feed conversion by cows. "The dairy cow excretion of N has to be reduced by between 10kg and 25kg/year if stocking rates cannot be cut. At current yield levels the average cow is excreting 118kg of N a year."

His route to reduce that to 100kg without loss of yield is to have a strict feed control programme. "Roughage will have to be analysed and feed allocated according to an optimised feeding plan. A measure of the urea in the milk will indicate if the feeding is properly balanced," he says.

His centre has produced a computer module which, with proper inputs, gives a print out of the cows daily excretion of nitrogen. It needs to be down to 300g/day to give an annual production of 100kg. &#42

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