When making the decision to delve into the world of silage additives, there are many important factors to consider before purchasing to ensure you’re not wasting money. At Forage Technology, we stress the fact that silage additives cannot help poor silage management, so, here are five things to consider before you spend on silage additive:
1. Crop Length
One of the most contentious issues in forage conservation is “how short should I chop it”, but this is actually the wrong question to ask – like everything to do with ruminant nutrition, it’s far more complex. There’s a major difference by country/normal weather conditions, so, for example in California, with dry, very hot climate, chop length is less important than it would be in Cumbria, where rainfall, humidity, and soil conditions are completely different. The key here is acidity – in the UK, wetter, younger cutting (especially the recently popular “multi-cut system”), creates a lower fibre/higher fermentability crop, which with very short chop, has a huge surface area for microbial fermentation, both in the silage clamp, and subsequently in the rumen. In the clamp, the effect – especially if exacerbated by “buffering capacity”, i.e. the ability to withstand pH change, often high in wet UK silages, particularly as a result of many years of slurry and nitrogen excess – is to produce very high levels of acid by reduction of valuable sugars. That then creates a low pH silage, which in turn directly affects rumen pH and health.
In addition, short-chopping is not necessarily helpful to the animal for the creation of the rumen mat, as rumination is dependent upon the ability to bring up and chew the fibrous content, encouraging healthy salivation (a buffer against acidity), and allowing a mechanical as well as microbial breakdown of the material at a controlled pace, to avoid any potential issues of either clinical, or sub-clinical, acidosis.
Key points: The “right answer” is very dependant on weather in the area and can affect pH and fermentability, and in turn, rumen and health.
2. Clamp Density
The often overlooked factor in creating “good silage” is the density; after rolling by heavy machinery, it isn’t sufficient to just throw a plastic sheet (even an “oxygen barrier” sheet) on top, and add a few tyres. By its very nature, conserved forage is “springy”, and silage making – which is literally pickling the crop in acid created by microbial action through conversion of its own carbohydrates, to lactic, acetic, and other Volatile Fatty Acids – is absolutely dependent upon the rapid creation of an anaerobic (oxygen free) environment. Thus, it really is as simple as the greater the compaction/weight/pressure on the top of the clamp, the more efficient the silage fermentation, and the lower the potential losses.
It is quite normal in UK silages to see losses of Dry Matter – a frequently misunderstood phenomenon in silage making, as the whole process involves a reduction of anything up to 40% of the harvested material, through various biological and management processes. What’s often not realised is that the “Dry Matter loss” is actually the HIGH VALUE fraction, not the indigestible fibre, hence the financial damage is significantly greater. With silage in 2018 trading at £40.00 per tonne, or higher, it makes absolutely no sense to willingly tolerate losses in this way – a farmer with reasonably good management is still accepting that if he cuts 1,000 tonnes of grass, he is ending up with 750 tonnes of lowered quality grass silage, and a loss of 250 tonnes potential with a value of £10,000.00.
Key points: Losing high percentage of dry matter is not a normal phenomenon, but greater compaction/pressure onto the clamp lowers potential loss.
3. Clamp Location
It’s hugely important when considering “where” and “how” to site a clamp/pit for forage conservation, that various factors are considered;
- Access needs to be direct and conducive to being able to cut a clean and tidy face from edge to edge, and from day 1 opening.
- Height needs to be manageable, so that machinery can run safely in the consolidation and pitting stage. Given that in some years, grass gains a particularly slippery epicuticular (waxy) coat, and is then susceptible to slippage within the silage clamp, it’s really important that a slight gradient is inbuilt in the silage floor concrete, to put pressure back into the clamp, not allow it to slide forward.
- Prevailing wind needs consideration – silage faces that are exposed to regular rain and weathering will deteriorate, and once acids have been “washed” off the face, the rapid progression of yeasts and moulds can exacerbate both DM loss, and introduce potential health hazards for both animal and human.
- Siting needs to avoid any potential contamination – proximity to slurry stores can be inviting disaster, and in a position in which field run-off can enter the pit (from side, or below), there’s potential for soil or other contaminants to be carried in.
- Ideally, a silage clamp needs to be inside, but given the scale and volume of many modern operations, that’s not always a practical proposition. Roofing can help to eliminate some problems, but in general, it will always come down to having the ability to manage the clamp/pit in such a way that consolidation and tidiness are served by its physical location and construction. It is far, far, better to have three long, narrow silage pits, than one extremely wide mega-pit.
Key points: Access, contamination and sliding all need to be considered.
“When to cut” is a question to which the answer in the UK will always be “what’s the weather been like, and what’s the forecast”. In theory, grass and other crops have an optimum time at which they achieve the maximum yield of nutrients in the maximum potential weight. So, it should be as easy as “I’ll cut my grass for first cut in the first week of May”…
…but it isn’t.
Cows need fibre, so it is bizarre how we frequently see fabulous silage analysis, and then a TMR diet including 2 KGs of straw. In a year in which Spring comes late, in which ground temperatures have been low, and in which rainfall has been significant, late applications of slurry and nitrogen may well have created a potentially awful silage, in which the main acid is butyric, and in which toxic levels of protein by-products can be created. The harvesting date needs to be the right date for the season and the year, and that will vary. There are many factors in play, from grass types, to macro element status, to ground conditions, to contractor availability, to maturity, to planning for requirements (a light first cut, followed by a drought can be extremely costly) etc.
Key points: Again, this is very much weather dependant – ask your rep for advice.
5.Long Term Payback
Farmers are regularly subjected to “More milk/meat from forage!” propaganda from the industry. It’s always the same story – promising vastly improved profitability by reducing purchased feed, and creating magical forage systems which slash or even eliminate costs by generating far more of the farms nutrition from its own soil.
Remember Dutch silage? Or the “New Zealand” system? Now it’s “Multi-Cut”. Do they work? Dutch silage works very well. In Holland.
In the UK, we need “UK silage”, and although we can make huge improvements in what we harvest, how we harvest, and how we then feed that conserved forage, it begins in the soil, and ends on the supermarket shelf. Future profitability, and the “pay-back” for a different approach to silage-making, needs to be an improvement on what WE in the UK do, not by attempting to adapt, or use, methods which are simply not appropriate.
Yes, it IS possible to get more milk from forage, and the rewards are potentially huge. If any UK farmer could gain 2 litres per cow per day from the farms own forage, the financial gain would be £20,000 p.a. per 100 cows.