Livestock farmers grazing brassica fodder crops should take care to introduce stock gradually and ensure appropriate supplementation.

This timely advice from William Fleming, Scotland and North-east England area manager for the forage company, Germinal, comes as the business reports a record acreage of forage brassicas being grown for autumn grazing and out-wintering, as well as unusual seasonal growth patterns that may warrant greater vigilance when feeding this autumn.

“Stock should be introduced steadily to fodder crops under any circumstances, with the recommendation being to start by allowing 1 – 2 hours access each day (around 10% of the dry matter in the diet) with this building to full access after 10 – 14 days,” William explains.

“This is more important this year where many crops have grown very rapidly – kicking on with optimum soil conditions following a period of drought – and may therefore be higher in nitrates than usual.

“Allowing stock time to adjust to a change in diet is important, as this maximises utilisation of the crop and avoids waste. It is also the best way to avoid any potential digestive problems.”

Mr Fleming added that brassicas should ideally represent no more than 70% of the dry matter of the total ruminant diet, at the point of full access, with a balance of fibre being provided in the form of hay, haylage or straw. The exception is when feeding milking cows, where levels should not exceed 20% of the diet dry matter, to avoid the possibility of milk taint. If in any doubt at all, regarding issues such as nitrate levels or milk taint, then the advice is to reduce the access to brassicas and increase the supplementary fibre.

“The ideal way to graze brassicas is to move the fence daily, allocating the correct amount for the stock being grazed, with supplementary bales in situ,” he adds.

“It’s also important to allow adequate access to water at all times and provide a run-back area for the stock to lie away from the crop. Brassicas are low in certain essential minerals, namely iodine, selenium, copper and cobalt, so suitable supplementation will be important.

Where grown on sloping fields, the best way to minimise potential problems of soil run-off is to graze downhill. Mr Fleming also advised farmers to avoid grazing crops that are frosted and to delay the time the fence is moved by a few hours to allow time for crop material to thaw.