8 August 1997

Inaccurate feeders could cost you dear

By Jessica Buss

PARLOUR feeder inaccuracy could be costing £40 a cow this year in wasted concentrate and having a detrimental effect on cow performance.

Dorset-based Genus nutrition consultant, James Shenton, says that a survey of parlour feeders revealed the huge extent to which feeders were over or under delivering. On the 48 farms visited, delivery was between 62% and 150% of the expected ration.

For accurate rationing

Mr Shenton believes that for accurate rationing feeders must supply concentrate within 5% variance; only 20% of those tested met this target.

"For a fresh calver due 7kg in the parlour, an error of just 10% is over or underfeeding that cow by 1.5 litres," he warns. "Inaccurate feeders are also a serious concern when relying on a high protein, 20%, concentrate to balance a maize silage ration. Overfeeding by 20% causes an imbalance between protein and energy supplied and this can cause high milk ureas, lameness and infertility. And underfeeding protein will restrict performance," says Mr Shenton.

He predicts that when overfeeding by 20% a cow that should be receiving 1.5t of concentrate a year, the extra 300kg of feed she gets could be worth £40.

In the study some feeders had not been calibrated for two years. As a minimum, Mr Shenton advises calibrating feeders twice a year, and also when changing types of feed, for example, when switching from a straight to a blend, or when changing supplier as pellet size or density can vary.

Although parlour feeders are often neglected, provided they are well maintained they can be accurate, he says. Ensure chains are kept tight in chain driven types and that brushes are replaced to prevent concentrate dribbling into troughs when feeders are knocked. When cows get into the habit of knocking feeders for more feed, it is difficult to maintain accuracy, he says.

"When calibrating feeders ensure that, with vacuum operated systems, the vacuum is on – it is not accurate enough to use the override levers."

Drop a single measure of feed in each trough and discard it. Then dispense five measures of feed in each trough, weigh each on kitchen-type scales, and average the weight by dividing by five. Just using one drop from each feeder is less accurate as each drop can vary slightly, warns Mr Shenton.

Feeders that become out of calibration quickly should be relied on less or replaced with feeders which have the mechanism out of cows reach. Feeding less concentrate in the parlour may be possible, but producers could also consider out-of-parlour feeders that are more accurate and need only one stall for 40 cows. These feeders can be expensive but usually have more advanced control systems than parlour feeders, he adds.

Ensuring parlour feeders are well-maintained could save £40 a cow.

PARLOUR FEEDERS

&#8226 Can waste valuable concentrate.

&#8226 Inaccurate when poorly maintained.

&#8226 Must be calibrated when feed type changes.