Feeding out silage efficiently this winter is going to be key to containing feed costs for your dairy herd … so what’s the best way to manage your clamps? Dairy Farmer asked Dr Tom Chamberlain, consultant veterinary surgeon, and consultant nutritionist Prof Mike Wilkinson for their advice.
Dry matter losses from silage during the feed-out period can be hefty, with industry figures suggesting they can range from between 4 and 19 per cent… so getting management right is crucial, especially in a year when milk prices are still below the costs of production.
“So much effort goes into producing good quality and nutritious silage, yet some farmers are prepared to accept losses in the clamp or at feeding time,” says Tom Chamberlain. “While good clamp management can improve daily milk output by up to 3 litres/cow, bad clamp management can cost a producer dear.
“Largest feed out losses are likely to come from slow daily removal of silage from the clamp, whether this be high DM grass, whole-crop or maize,” he says.
Prof Wilkinson says that the target progression rate through the silo should be a metre a week in winter, and two metres a week in summer… the faster rate due to warmer weather and more rapid aerobic deterioration of silage.
“Farmers should work out how fast they are progressing through the silo, starting with the amount of silage they’re removing each day,” he says. “For example, if you’re feeding 4000 kg of fresh weight daily, divide it by the density (say 700 kg/cubic metres) and this will show you are removing 5.7 cubic metres from the silo daily. At a depth of grab of 0.75 metres this is equivalent to 7.6 square metres of feed-out face area per day.
“Next you need to know the total surface area of the silo face – say it’s 14 metres wide by 3 metres high, that gives you 42 square metres. So, removing 7.6 square metres a day means it will take 5.5 days to get across the whole face.” You are removing 0.75 metres depth in 5.5 days, or 1 metre in 7.3 days.
Prof Wilkinson says an alternative way to measure is to make daily marks on the silo wall, calculating the total progression by the end of each week.
“It’s important to know your weekly progression rate,” he says. “Hitting the metre a week target this winter will help to ensure your silage keeps its quality and reduce any chance of aerobic spoilage within the clamp.”
Maintaining silage quality requires correct sealing of the clamp when the crop is ensiled – and here Prof Wilkinson recommends using the innovative oxygen barrier film Silostop, the only proven oxygen barrier film, which offers the best and most cost-efficient seal. “A silo 3 metres high contains a third of its volume in the top metre where silage density is around 25% lower than in the core of the silo. The top layer is most vulnerable, therefore, to deterioration during the storage period”, he says.
Silostop film provides an effective oxygen barrier and creates the right anaerobic conditions. It also facilitates a faster, more efficient fermentation process to deliver enhanced quality silage in the top layer and at the shoulders of the silo. When applied, the film follows and clings to the top surface of the clamp, preventing pockets of trapped air and reducing aerobic spoilage on the top or shoulders. The thin orange (45 micron) film needs protecting from physical damage, either with a second standard plastic sheet (125 microns thick) or with anti-ultra violet light protective netting over the top. The new Silostop Max film is thicker (80 microns) and has UV protection built in, so it only needs a protective net cover.
Remember that oxygen is the enemy when it comes to making and keeping high quality silage,” says Dr Chamberlain. “The aim should be that the silage at the top and shoulders of the clamp looks and feeds just as well as that from the middle.”
Another piece of advice is to ensure that loose silage is not left lying around the base of the feed face. It will have been fully aerated on removal, and is likely to heat up and go rotten rapidly. Also, consider ways to deter birds, badgers and rodents from the feed face – they bring the risk of contamination of the silage with undesirable microorganisms such as salmonella and TB.
Next Dr Chamberlain stresses how important it is to cut out the silage to leave a clean and undisturbed face.
“There are three options here:
Use a fork or bucket on a front-end loader pushed upwards – this is the worst option as it opens cracks which can allow air in as far as 2 metres, and leaves a ragged face behind;
Use a block cutter or shear-bucket – this is better than the buckets above but the challenge is to make sure cracks don’t open at the base of the block;
Consider using de-facers (used more widely abroad) particularly when moving maize or whole crop – they don’t work so well with long chop grass silages.
“ Only roll the top covers back a maximum of 2 metres from the front edge, and use Silostop Silomats to keep air away from the exposed top surface and to avoid working too close to the unstable top edge.”
Traditionally farmers have used old tyres to weight down the top sheet and over the years these have perished, exposing the internal reinforcing wires which can drop off into the silage. If the wire is accidentally incorporated in the ration, this can cause reticulitis, reduced intake and production and can be fatal.
“If you must use tyres, assess them carefully through the winter,” says Dr Chamberlain. “As you move back across the clamp check the tyres and discard any that have perished, before you end up with problems.”
He stresses that gravel bags are better than tyres. They should be placed in a continuous line all around the edges and in a grid-like pattern over the top surface.
“Finally I would remind farmers that based on the cost of replacing it, silage is worth about £30 a tonne, and if you lose just 10 per cent from feed-out losses, you’re losing £3 a tonne – and that’s £6000 on a 2000-tonne silo. You will have less silage to put in the feed trough and the material that goes in has reduced feed value.”