The first of a two-part series from Volac explains why putting a little extra time and effort into silage-making could really make a positive difference to your bottom line.
Following a wet and mild winter, silagemaking conditions could be more challenging than ever this year – and with budgets already stretched, good conserved forage management is essential to make the most of this vital home-grown fodder.
With the warmer temperatures resulting in continued grass growth throughout most of the winter months, one of the main issues farmers should be aware of is the potential for dead material at the base of the swards. This will lower the digestibility and protein content of the grass and reduce its energy value. It also contains higher levels of bacteria and fungi, which can challenge silage fermentation and increase the risk of aerobic spoilage at feedout.
The longer grass makes slurry and manure application more difficult too.
Independent silage consultant, Dr David Davies, says: "Surface application in these circumstances will increase the risk of contaminating the new growth with bacteria, such as enterobacteria and clostridia, which can spoil the fermentation."
Dr Davies says now, more than ever, the silage-making process must be spot on. At harvest, he suggests a minimum cutting height of two to three inches followed by a rapid wilt.
“To minimise soil contamination – another source of undesirable micro-organisms – tedders and rakes should be adjusted while sitting on a hard surface, to ensure they won’t hit the ground in the field.”
However, when it comes to preserving the goodness in the forage and avoiding aerobic spoilage, he advises consolidation in the clamp is the most important factor to get right.
“This is the biggest issue in the UK when it comes to best silagemaking practice, and it is essential the time is taken to carry it out effectively. The denser the silage is, the less oxygen can get in, reducing the chance of spoilage.
“Build up the clamp using layers no thicker than 15cm to ensure effective compaction throughout and roll it continuously. Aim for a density of 250kg DM/cu.m.”
Likewise, Dr Davies stresses the importance of sealing the clamp properly, including the ramp.
“Use high quality, overlapping sheets, weighed down well, especially around the edges.
“It is all about getting the most out of this home-grown asset and effective compaction plays an essential role in helping to lower losses,” he says.
As for conserving the nutrients in the original forage, good fermentation is a must and Dr Davies suggests using a homo-fermentative inoculant to help improve the speed at which it takes place.
According to Ecosyl’s technical adviser Dr Shirley Heron the key to successful fermentation is achieving a fast pH fall.
“This has two main benefits,” she says. “Firstly, it prevents the breakdown of the true protein in the crop which benefits the rumen, and secondly, it inhibits the activity of undesirable micro-organisms, such as enterobacteria and clostridia, which waste sugars and increase DM losses.”
Old grass which has continued to grow through the winter will be of poorer quality and more susceptible to naturally-present undesirable bacteria.
To achieve a rapid pH fall, Dr Heron says it is necessary to maximise the amount of lactic acid produced as this is the strongest acid generated in silage fermentation. It is also produced with no loss in DM, unlike other fermentation products. To assist with this, she suggests using a silage inoculant designed to improve fermentation.
“These apply large numbers of the types of lactic acid bacteria that only produce lactic acid. The single best species for doing this is Lactobacillus plantarum, which is why it is found in most silage inoculants, though there are many different strains which differ in their individual characteristics,” she says.
Dr Heron adds that the biggest losses with silage – as much as 50% in badly heating silage – are caused by aerobic spoilage, and for this, she says, additives can make a huge difference.
“The extent of aerobic spoilage is often not appreciated as losses are largely invisible carbon dioxide gas. However, it is likely to be a bigger problem this year as the yeasts and moulds which cause it will be present in higher numbers on the fresh crop due to there being more decaying vegetation at the base of the sward.
“Additives help by giving you a longer window before spoilage starts as well as reducing the severity when it does. With first cut grass silage worth about £135/t DM and the need to get more milk from forage greater than ever before, farmers cannot afford to be wasting any of it, so the case for using an additive is stronger than ever.”
Dr Heron stresses farmers must do their homework before buying an additive.
“There are many different additives available – to maximise the chance of success, choose one which has plenty of evidence behind it to prove it will deal with the particular issues faced.
Losses in dry matter and nutritive value are inevitable and occur at various stages during the harvesting, ensiling and feedout process but the key is good management to try and limit those losses as much as possible, adds Dr Heron.
Both Dr Heron and Dr Davies agree putting in extra time and effort in the silage-making and feeding process will reap benefits in the long-run – especially in the current climate.
“Farmers are under huge pressure financially at the moment, but if they are to make the most of their forage they need to be treating their silage more like a valuable home-produced concentrate. silage production costs the same whether you make a good job or a bad job, but the value good silage adds to the performance of the animals is phenomenal,” says Dr Davies.
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