Dairy farmers are being advised to have silages reanalysed, following increasing numbers of herds reporting disappointing milk protein contents due to poor quality forages being fed.
Tony Evans of Andersons Consultants says many cows are failing to yield anywhere near anticipated levels of milk, while milk urea levels are far short of where they should be. “One client had grass silage analysed recently which contained just 8% protein,” he explains.
“Retesting silage is the best option, as it will give an accurate picture of what silage quality is like now and allow rations to be formulated to correct any problems. Where ration protein levels need quick and significant correction, rape is the best choice, as it is a cheaper option than soya, where large quantities are needed.”
Meanwhile, East Anglia-based Kite consultant Ben Watts says many maize silages are high in starch content, which is also causing problems for some herds. “These need buffering with bicarb or something similar to correct problems. Where maize was tested early it is best to retest now, as many early analyses are likely to be misleading compared to an analysis done now.”
In some cases it may be beneficial to add some extra chopped straw or other long fibre to diets in order to slow down ration progress through the rumen and allow more time for available protein to be absorbed, adds Mr Watts.
Nantwich-based vet Neil Howie says monitoring milk urea is a good measure of protein use. In general terms the lower the urea level the better, as milk urea is a sign of poor protein use in the rumen. “The higher the milk urea, the poorer the protein use,” he says.
And it is important to remember that a bulk sample is just a representative sample of the herd, so there may well be high and low milk urea cows in the herd, warns Mr Howie. “When urea levels are worryingly high or low it is always worth doing a set of blood tests to back up the bulk sample.
“When cows are failing to get enough protein from the diet it is likely the bugs in the rumen will fail to thrive and hence will not break down fibre in the diet as well as they should do. This will then lead to an energy deficit and cows could well lose condition.”
Also there could be a danger where dry cows are being fed low protein rations that they have insufficient antibody response post- calving, reckons Mr Howie. Where rations are being changed to account for poor quality forage he reminds producers to allow at least 10 days for cows to adjust to new ration ingredients or mixes.
And, following this year’s dry summer, he believes there may well be some high potash silages on farms, which could also cause problems. “High potash in winter rations could lead to an increase in milk fever cases and could in exceptional cases even cause staggers.
“This year it will be worthwhile not pushing cows for that extra litre of yield and taking a longer-term view, taking fertility and cow condition into account,” he suggests.