Silage is one of the biggest cost items on many dairy farms’ accounts. With a value of £30 a tonne, and a 200 cow herd needing some 2000 tonnes, that’s a feed worth £60,000 a year. But do producers realise the value of the crop they’ve ensiled? Most of the time no, says Silostop’s Tom Chamberlain who, as farmers across Britain prepare to bring in the maize, gives this useful advice on how to manage - and make the most of - this valuable winter forage.
“The first thing farmers must do is take control. With the majority of the crops cut and ensiled by contractors, it’s all too easy to sit back and let them manage the harvest and the clamp. But producers must get far more involved in the whole process, and be sure they’re there, taking an active role, throughout the operation.
“First off it’s important to harvest at the right time. You should be targeting a plant dry matter of between 30 and 35%, but the challenge is that few farmers are basing harvest dates on measured dry matters. In the UK we tend to use the milk line as a sign of when the crop is ready – targeting harvesting when the milk line is a third to half way up the grain. In the USA, many farmers run forage dry matter analyses through the harvest season: a few plants are collected, chopped and quickly dried to inform them as to when it is best to harvest the crop.
“I don’t know anyone doing that here, yet if the crop’s too wet it’s acidic, and not rumen-friendly to feed. Early cut crops have lower starch content and a lower nutritional value. Then, when the crop is too dry, the problem is getting the right compaction in the clamp.
“Next it’s about the height at which the crop is harvested. A good crop will be between 2 and 3 metres tall, and it’s crucial to leave the right amount of stubble, between 20 and 30 cm. Too low, and you’ll pick up soil which can lead to bacterial contamination. Generally, the higher up the stem you go, the better the quality. If the crop’s a bit light, it’s always possible to cut a bit lower to bulk up the volume.
“Chop length is the next consideration. A cow wants a longer chop length of over 18 mm because this supplies good quality structural fibre and gives her something to chew on. The more we can get her to chew the better, as this will improve rumen health.
“But, it’s tempting to cut shorter as this reduces the load on the corn-processor and speeds harvest rates - so the farmer must watch out for this. A shorter chopped crop will also compact better in the clamp, especially if it’s a bit too dry. Monitor the chop length and cut wet enough to allow for good compaction in the clamp.
“One tactic used by some farmers is to chop longer until they get close to the top of the clamp, then reducing the chop length in the final loads that make up the top layer to improve the consolidation. Many newer forage harvesters can vary the chop length while chopping, and this makes a lot of sense, so try it this year and see how it helps. Other things to try would be to cut the wetter crops last so they cap the clamp. Harvesting the most remote fields last may also help as it will slow the delivery rate and give more time to compact the final loads.
“And, as the maize goes into the clamp, there’s a need to check each grain is slightly cracked. The yellow husk must be split, otherwise the cow can’t digest the contents. This is the slower part of the job as the cob is passing through the grain processor in the harvester, and one that must be carefully monitored. Ideally grains should be cracked, not slashed to ‘mush’.
“Speed of harvest is one of the biggest areas that needs careful control. Generally, the speed is increasing as equipment gets bigger and better. But you have to remember that your facilities aren’t getting bigger – your silage clamp hasn’t suddenly grown, for example.
“If the forage harvester is cutting at 100 tonnes/hour, the weight of the tractors working on the clamp should be at least a quarter of the filling rate – so in this case, around 25 tonnes. Ask yourself whether you know how fast you are filling the clamp… are you there, counting the trailers in? And the tractors on the clamp should be running continuously, it’s very difficult to over-compact, most farmers under-compact.
Filling the clamp
“When you’re filling the clamp, fill long and low. Fill and compact the entire length of the pit with even layers, no more than 15 cm at a time. If the layers are more than 30 cm deep, it doesn’t matter what weight of machine you’re using, you won’t get the layer of compaction needed.
“Cover the clamp immediately, and use Silostop®, an oxygen barrier film to seal the clamp and keep the air out – oxygen is the enemy when it comes to making good silage. There’s little point in paying attention to all the steps necessary to get the quality of maize silage into the clamp, and then not looking after it. The aim should be that the silage at the top of the clamp looks and feeds just as well as that from the middle.
Covering and sealing the clamp
“Silostop® is unique in its oxygen barrier properties as it’s the only proven oxygen barrier film. It is usually used as the first part of a two-step covering. A 45 micron oxygen barrier film is used as the first step. This orange film is thin, and therefore clings to the contours of the silage, pushing the air out, sealing the surface and stopping further air from entering via transmission through the plastic. This thin film need protecting from physical damage with a second simple plastic sheet (around 150 microns) and a then protective netting over the top. Silostop® nets, Silomats and gravel bags are recommended. Gravel bags should be laid around all the edges, any joins, and cross hatched over the entire pit.
“For farmers wanting to only use a single sheet of film Silostop® offers an 80 micron oxygen barrier film, Silostop® Max that only needs covering with a net and securing with gravel bags.
“Both options virtually eliminate aerobic spoilage, removing the opportunity for oxygen to get inside the clamp, meaning every bit of your harvested crop is ready to feed. Covered and sealed correctly will result in no waste and improved aerobic stability. The silage smells much better too, it’s cool and is more palatable for the cows. Finally, it allows you to feed a really good quality silage that can have many other longer-term benefits – reducing the amount of concentrate that needs to be fed, for example”