Silage quality was unexciting last year – so what lessons can farmers learn to avoid a repeat in the coming season?
Weather will always have a major impact on silage quality – but 2016 was a relatively benign year. So why did quality fail to meet expectations?
According to Derek Nelson, product manager for Ecosyl, one of the main reasons behind the reduced quality was the low milk price, which led many farmers to cut costs to the bone. He says: “We know people treated less silage with an inoculant.But farmers are now seeing the impact of that in silage which isn’t feeding out very well, and is suffering from lower energy and protein levels. It’s important not to make the same mistake again.”
Grass yields in some cases were also down, probably due to reduced fertiliser applications. Some farmers may also have cut back on the use of contractors, he adds. “Remember, if cutting was late, the digestibility of grass silage after heading falls by about 0.5% a day.” To improve silage yields and quality this year farmers should be honest and scrutinise the impact that cutbacks in all areas may have had in 2016.
“The recent increase in milk prices is clearly good news, but if silage quality or quantity isn’t there, you’ll have to rely more on bought-in feed to take advantage of this. A lot of the milk price increases in the second half of 2016 were swallowed up on some farms by higher purchased feed costs.”
Mr Nelson recommends planning ahead now to ensure the best possible silage quality and yields in 2017.
“If cutbacks were made on grassland reseeding in 2016, there is an opportunity to reseed in spring. And when it comes to preserving the nutritional value of silage, look for a silage additive which is proven. That means proven not just for fermentation, but also for subsequent effects – in particular, for reducing dry matter losses, maximising feed value and, ultimately, for increasing milk yield per cow.”
Scott Kingston farms with his father Nigel and brother Matt, at Tresham Farm, Wootonunder-Edge, Gloucestershire.
Milking 240 Holstein cows, they are always trying to get as much milk from grass and forage as possible to boost productivity or cut purchased concentrate costs. Calving all-year-round, Mr Kingston houses the high yielders and feeds them a total mixed ration comprising grass and maize silage and concentrates.
The low yielders, youngstock and beef cattle are grazed on a paddock system from spring to autumn, with buffer feed given when needed. In total the farm comprises 200 hectares, of which 60ha are arable and 57ha are permanent pasture, with the rest sown to grass or maize. “We reseed silage leys every three years and grazing pasture every five.”
Although the family like to make four cuts of grass silage over the year, the free-draining Cotswold brash tends to dry out over summer, in which case the silage ground has to be grazed. “We have a 22-day grazing rotation, turning the cows onto a 1.8ha paddock for 24 hours before moving them on,” explains Mr Kingston. He measures the grass to plan the rotation and makes the best use of his slurry as possible, injecting it with an umbilical to minimise atmospheric losses.
The basic premise of making silage is to preserve it through a process of fermentation, turning sugars into acids which essentially pickle the crop. But there is a lot which can go wrong, sapping the silage quality and increasing losses.
The first decision is when to cut: Are you aiming for maximum yield or high quality and digestibility? There is usually a compromise to be had, cutting earlier for high D Value and later for larger yields. As soon as the grass is cut it starts changing, as plant enzymes begin the degradation process.
Ideally, grass should be at 28-32% dry matter when it goes into the clamp – if it is too wet it will affect the fermentation process and increase effluent losses; too dry and it will be difficult to compact, leaving more air inside the clamp.
However, there is a balance to be found between increasing the grass dry matter and preserving its quality, so it is important to choose the optimum weather conditions for rapid wilting. Spreading and turning cut grass will speed up wilting, but you must avoid contaminating it with soil.
It really is a race against time – the longer the grass is in the field the more natural bacteria, yeasts and moulds will be using up those nutrients you are seeking to preserve.
Once wilted, get the grass into the clamp, compacted and sealed as quickly as possible. Fermentation has to take place in anaerobic conditions, otherwise aerobic bacteria will use up important sugars, so it is vital you exclude as much air as possible.
The aim is to acidify the crop rapidly, dropping the pH from 6.5 to around 4 within 24-72 hours, to prevent the growth of undesirable bacteria. While this process will happen naturally, it can be quite slow, so adding an inoculant such as the beneficial lactic acid-producing bacteria Lactobacillus plantarum will speed it up and improve nutrient preservation.
Ecosyl contains the MTD/1 strain of freeze-dried Lactobacillus plantarum which is mixed with water and sprayed onto the silage when it’s chopped. At a cost of £1.40/tonne treated, Ecosyl can give a return on investment of three to one through improved silage quality and reduced wastage (see table, below).
Slow, inefficient fermentation – which can be measured both through pH and the lactate: acetate ratio (lactate should be high, acetate low for good fermentation) – means loss of valuable sugars. It can also lead to secondary clostridial fermentation resulting in excessive protein breakdown into ammonia and the production of butyric acid, both of which lead to bad smelling silage which may reduce intake.
Having made the best silage possible, it’s important to preserve that quality when it comes to opening the clamp and feeding it out. Once oxygen is present moulds and yeasts will begin to use up the lactic acid, leading to spoilage.
Design the clamp to minimise the face area, and keep the clamp face as clean and tight as possible, using a block cutter rather than pulling the silage out.
Treated and untreated grass with an initial DM of 27%
|Lactic acid (g/kg DM)||31.9||91.9|
|Acetic acid (g/kg DM)||9.3||15.6|
|Butyric acid (g/kg DM)||44.1||0|
|Lactic acid:Acetic acid||3.4||5.9|
|Ammonia N (% total N)||10.7||4.3|
|Dry matter loss (%)||11.8||4.7|
“We sample our soil every four years, and apply inorganic fertiliser in March to take the first cut of silage as early in May as possible. We are pushing for high quality, not yield, so try and cut at least every five weeks if we can.”
The family set up all the machinery in advance, to avoid breakdowns at critical times, and carry out all the foraging work themselves.
“That way we can pick and choose when to go, and which areas to cut – getting it right is worth a lot of money,” says Mr Kingston. He uses a mower conditioner and spreads the grass out to wilt for 36 hours. “We ted it and use a double rake to bring two mower widths into one swath to harvest with a trailed harvester.
All the first and second cut goes into the clamp, along with some of the third cut – the rest is baled.” Two tractors work on the clamp, with a buck rake and double wheels on the telehandler for good compaction. “We use clear and black plastic sheet and green nets to keep the birds off, all weighted down with tyres,” says Mr Kingston.
“It’s slower using a trailer harvester than a self-propelled one, but I don’t know if we could deal with a faster rate coming into the clamp. Faster isn’t always better.” In the past, feeding silage to the housed cows over summer has proven challenging. “We’ve had quite a lot of wastage as the face heats up,” he explains. “White mould isn’t ideal for the cows, and as you take the sheet back you end up with wastage on the top as it heats up so fast.”
This year Mr Kingston decided to use Ecocool, an additive which is applied to the silage as it is chopped in the forage wagon. As well as a bacterial inoculant to improve fermentation, it contains a second bacterium for improved aerobic stability.
“I’m really pleased with the results – we’re about halfway through the clamp now and none of the face has heated up at all,” he says. “We feed in troughs so it’s hard work clearing out bad silage, but I haven’t had to chuck anything out this year.
That’s saved a lot of money, as well as time in not having to pull off bad silage from the clamp. It’s paid off many times over – you only need a minuscule improvement in quality and usage to make it worthwhile.”
The family try to leave the clamp shut for 10 weeks before opening it up, and this year it has averaged 11.5MJ ME, 14.8% protein and a D Value of 75.4. “We’re averaging 4,500 litres from forage, with a lactation average of 9,800 litres per cow,” says Mr Kingston. His margin over purchased feed is 19.84ppl, with concentrate costs of 7.01ppl.
Doing all the feeding himself, he tries to keep the face as tight as possible, using a sharp sheer grab and only taking the sheet back as far as necessary. “Unfortunately, the face is quite wide as eventually we want to increase cow numbers, so it’s not ideal, especially in summer. But by making the best quality silage possible, and preserving that quality, we can decrease concentrate use in our youngstock and push our milking cows just that little bit harder.”