Silage hygiene and why is important
The image of silage to non-farming folk is dominated by “that” smell. It’s an image that couldn’t be much further from the ideal of “clean”, so why are we concentrating on the hygiene side of silage making? The answer is, as with all the topics in this series, to make better silage and reduce the invisible losses.
The ensiling process takes fresh forage material and preserves it for later use by a process similar to pickling. And just like any kitchen preserving protocol, hygiene (and sometimes sterilisation) is fundamental to a palatable outcome. For the farmer, the jars are silage clamps, the utensils are tractors, trailers, mowers, rakes and choppers and the crop makes its own vinegar so we don’t need any tanker deliveries from Sarsons. There are differences between the kitchen and the clamp, but the “make sure its clean” rule still applies to both preservation processes.
So where are the dirty areas?
Most commonly, the issues are with contamination of soils and slurries. Soil is a complex mix of minerals and organic matter that contains billions of bacteria in each handful. Any soil contamination introduces a massive inoculation of unwanted and unwelcome bacteria into the clamp. Slurry and muck are the indigestible elements of livestock diet together with billions of dead, dying and living bacteria from the host’s gut. Again, even the slightest contamination can introduce huge numbers of unhelpful bacteria to the silage.
The ensiling or pickling process relies on the fact that unwanted bacteria, yeast and mold struggle to function in very low PH conditions. The PH of silage can be as low as 3.5 – 4.0. At these levels almost all life forms cease to be active and the crop is preserved with the feed values intact.
So if the PH is so low that nothing else thrives, why do we need to bother about soil and muck contamination?
The answer to this is down to those Sarsons tankers – or lack of them. You are relying on the crop itself to produce the acid to pickle the silage - more specifically, the bacteria that live on the crop. These helpful bacteria get to work “eating up” the sugars in the crop and producing acid as a by-product. Hopefully most of these will be lactobacillus bacteria and they will produce lactic acid. The problem is the lactobacillus don’t have it all their own way, it’s a battlefield of competing life forms in the clamp between yeasts, bacteria and molds of many different species. We hope the friendly guys are going to win this battle but during the struggle, more and more of the valuable feed value of the crop is used up by the various life forms in the clamp. This is where the invisible losses occur as you will probably never know what you have lost unless you are using some sophisticated harvest analysis. But you can give the good guys a better chance of an early victory by limiting the numbers of the bad guys in the silage.
So what can you do to help?
Firstly clean out the clamp before you start filling the new crop. If last years silage was “good” then a simple wash down will be good enough, however if last years as a poor or butyric fermentation then consider disinfecting the clamp to make sure you limit the carryover for bacteria to the absolute minimum. If you are re-using drainage pipes or sheets make sure these are clean too. Again if the previous use was in a “poor” silage fermentation, replace the pipes or sheets, the cost savings of reuse will be more than offset by in clamp losses.
Next on to the kit. If it’s your own machinery pressure wash the mowers, rakes and the chopper just before you go to work. Where it’s the contractors machinery, make sure you check it over before they go to work and wash it off if its dirty.
The machines in the field are one thing, but the ones that work around the clamp are even more important. The buckrake or loading shovel is critical and you should wash this one even if it looks clean – especially the underside and the tyres. The same goes for the trailers, inside and out.
Time to think about the access to the clamp, make sure the roadways are as clean as possible. If possible separate livestock from silage routes for the harvest day(s). In a wet year, or where it’s impossible to separate the traffic routes, ensure the “dirty” vehicles don’t enter the clamp. Tip trailers at the very front edge of the clamp with the shovel working at 90 degrees to eliminate cross contamination.
Any spillage or contamination needs to be dealt with immediately. If there’s an oil or fuel leak or some livestock escape, contain it as quickly as possible and dispose of the contaminated silage appropriately. It might only be a really small area but “one rotten apple..” and all that.
Don’t ruin all the good work when it comes to covering the clamp. Pay particular attention to the weights used to hold the covers down. Particularly old tyres that contain foul smelling dirty water, make sure that water doesn’t run off the sheets into the silage!
The same rules apply once the clamp is open and the feeding out has begun. Keep the kit, the silage face and the floor as clean as possible to limit the chances of unwanted secondary fermentations.
In summary, as with most things, the devil is in the detail and although hygiene is never glamorous or exciting – it is critical to making every clamp a good silage.
If you need further information or help on how to keep your silage clean, or for any of the other aspects of silage making covered in this series – contact Jeremy Nash @ jeremynash1@btinternet.com