Tips for improving your farm’s clamp compaction

Better clamp compaction could allow farmers to expand herds without increasing their acreage by improving silage quantity and quality.

At Carreg-y-Llech, near Mold, farmer Edward Morgan hires contractors to make his silage, but the one job he keeps “in-house” is the rolling of the pit.

“It is the most important job at silage time, how well it is done can have a huge influence on the performance of our cows and our feed costs during the winter,” says Mr Morgan.

Silage is crucial for getting the most out of his autumn block-calving, 190-cow pedigree dairy herd, which has an average annual milk yield of 8,500 litres. Last year’s silage analysed at 11.3MJ/kg dry matter, with a crude protein of 15.4% and a D value of 70.

See also: Eight-point plan to making better quality silage

“When the silage is carted in we make sure we compact the top 6in before adding another layer.” This keeps air out of the clamp and prevents it from heating.

Mr Morgan’s attention to detail on the clamp is not typical of most dairy farms, suggests David Davies, of Silage Solutions.

Improving clamp compaction

He says a large number of UK farmers get clamp compaction wrong and as a result incur dry matter losses of between 25-30%.

“Clamp density should be at least 320kg/cu m of dry matter, but on UK farms it is between 160kg and 180kg. Even at 320kg, there will be 10% losses, while the sheet is on,” he says.

Dr Davies urges farmers to improve clamp consolidation. “In my view this is what British farmers are the worst at. If you don’t get good consolidation there will be issues all the way through,” he warns.

He recommends filling silage clamps in even layers, no more than 15cm deep, and rolling after every layer is added.

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“The most important person during silage making is the person on the pit,” says Dr Davies. “Some farmers roll for four to five hours at the end of the day, but that’s no good, they need to roll as they go along.”

Dr Davies does not advocate using tractors with double wheels on the clamp.

These are designed to reduce compaction in a field, but the opposite effect is needed in a clamp.

Instead he recommends using a Silapactor – a 4t tool made with train wheels – to improve silage compaction when filling the clamp. The machine is designed to exert pressure across its full 3m width, increasing compaction density with each pass.

Benefits

He reckons getting this right could allow farm businesses to expand their herds without necessarily increasing acreage.

Denser silage can also reduce mould because oxygen levels are lower. A US trial highlighted that poorly consolidated silage had 100,000 yeasts/g where as well compacted silage had fewer than 100, days post- ensiling.

“These yeasts cause aerobic spoilage and will result in heating and moulding of the silage during feed-out, further adding to the losses,’’ explains Dr Davies.

He recommends measuring density by removing a core sample and measuring the depth of the hole in the clamp.

“Weigh the amount of silage removed with the corer and divide the weight of the silage by the volume. The target should be about 250kg/cu m of fresh matter (750kg DM). If that target can be achieved the quality will be improved and above that losses will be reduced.”