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Silage season is moving into top gear this week given the recent improvement in the weather.
For many farmers, the priority will be to harvest as much grass as possible, which probably means they will opt for a later cutting date in an effort to maximise yields.
With silage reserves depleted after one of the worst winters in living memory, it is understandable that some farmers would go for bulk, as opposed to higher-quality silage which tends to be lower in yield.
But there is a compromise that can be made between silage quality and yield.
Leaving cutting date until late June will have a negative effect on the yield of second-cut, and possibly third-cut silage, which means silage stocks will remain under pressure next winter.
In addition, by focusing solely on silage yield, the resultant fodder will be lower in digestibility and therefore lower in terms of feed value.
This could make silage unsuitable for dairy cows, summer- and autumn-calving suckler cows with calves at foot, or finishing cattle.
These animals will require higher levels of concentrate supplementation to maintain lactation or high levels of liveweight gain next winter.
Feed value
In contrast, harvesting silage before it has produced a full seed-head will improve the feed value of fodder, and with higher sugar levels, fermentation is improved, minimising waste.
Fewer concentrates are required to maintain performance, and there is also the option of restricting high-quality silage to dry cows next winter, and therefore reduce costs.
With settled weather forecast over the coming week, there may be an opportunity for farmers to harvest silage earlier than planned.
Outlined below are 10 steps to making good quality fodder this year.
1 When should I cut grass?
There are two ways to gauge when grass is ready to cut. The first is to cut just as seed heads are staring to emerge from the plant. The second is to go once the base of the sward is turning white.
Once seed heads start emerging, feed quality will begin to decline. A good rule of thumb when cutting silage is that the D-Value of silage will drop by three units for every week once seed heads start to emerge.
Therefore, delaying cutting date by two weeks because of weather, or trying to increase yield, will reduce the feed value by as much as six D-value units. This would require an extra 1.5kg per head per day of concentrate feed to growing cattle just to maintain performance.
Once the sward base starts turning white, grass growth will slow. Therefore, there is no benefit in delaying the cutting date beyond this point, as there will be little increase in yield.
2 Target a second cut
if grass is harvested by early June, grass aftermath should green up quickly.
Applying fertiliser and slurry shortly after first-cut silage should mean it is possible to harvest second-cut silage in six to seven weeks, still leaving the option of a third cut, or the potential to add significantly to late season grass supplies.
This should make up for any potential yield lost by the early harvesting of first-cut swards. Waiting for bulk in a first cut limits options for later in the year.
3 Take out surplus grass from the grazing block
With grass growth increasing significantly over the past week, grazing swards will be starting to get ahead of cattle.
By walking swards now, you can decide which paddocks can be closed up and cut for silage along with the main first-cut within the next couple of weeks.
Avoid the temptation to go with fertiliser in an attempt to bulk up the grass in a paddock. Taking a heavy cut off this area will mean it is slower to recover, and could leave you short of grass in the next rotation.
Remember, grass growth tends to slow in early to mid-July irrespective of the weather.
4 Wilting
The late spring means that many silage swards were fertilised much later than planned. Therefore, there is a risk of having residual nitrogen in swards that are cut in the coming weeks.
However, wilting grass for at least 24 hours after mowing, will increase the dry matter of grass, and reduce the likelihood of a poor fermentation due to the presence of higher levels of nitrate in the crop.
Grass can be tedded out as soon as possible to increase the speed of wilting, although this will increase contractor costs by at least £5/acre.
Where tedding out grass is not an option, set the mower to spread the swathe at the widest possible setting, and again leave for a period of 24 hours before lifting (a maximum of 36 hours).
The target should be to ensile grass once it has a dry matter above 25% to 30%. If grass is mowed dry in good weather, the dry matter should already be around 20%, so a 24-hour wilt is all that is required. Avoid over-wilting to dry matters above 40% as this will increase losses in the field, make the material harder to ensile and increase the potential for losses at feed-out.
If grass cannot be wilted because of broken weather, and there is a risk of residual nitrogen in the sward, a silage additive will help to produce a stable fermentation.
5 Mow and lift in the afternoon
The best time to mow grass is the afternoon as grass sugars are at peak levels.
Grass has a lower dry matter in early morning, meaning there is a greater risk of nutrient loss and a longer wilting period is required to reduce moisture levels.
Harvesting should also start in the afternoon for similar reasons, although when using the services of a contractor, this is not always an option.
6 Do not over chop
Chop length of silage should be no shorter than six inches in length, which is around the width of a cow’s muzzle.
Silage that is too short becomes harder to ensile, as it is difficult to expel air properly, therefore increasing the potential for waste.
Over-chopping grass also increases the level of grass lost in the field during the lifting and transport process.
Shorter grass will pass through cattle much faster, therefore additional fibre such as straw might need to be offered to cattle to slow down digestion.
7 Fill the pit evenly
Silage clamps should be filled as quickly and evenly as possible. It is important to roll and compress grass during the process to expel air from the pit.
Once all the grass is ensiled, a tractor used to roll the pit will only be effective at expelling air to a depth of 30cm below the tyres.
Therefore, poor filling technique when buck-raking can cause poor fermentation, especially along the shoulders of the pit, increasing the amount of waste silage.
8 Do not roll the next day
Once the pit has been filled, roll the pit until it is levelled and compressed. Even if finishing late in the evening, it is better to complete this task as quickly as possible.
If possible, do not be tempted to start rolling again the next day. Once grass has settled and starts to sink, there is a risk that further rolling can suck air back into the pit again.
9 Seal the pit properly
Once the pit has been filled, it should be covered as soon as possible to kickstart fermentation. Lining the side walls of the pit with an old cover can help to improve the seal along the shoulders of the pit, improving fermentation and reducing waste.
A couple of days after sealing, go back up along the walls and refit tyres or sand bags that will have moved slightly as the pit sinks.
10 Stacking bales
If baling silage, make sure bales are tightly packed to retain their shape. Bales stacked on their end are less prone to sagging, especially if stacking more than one row high.
Wrapping bales close to the stacking site reduces the risk of damage to plastic. Mark the bales in terms of sward quality if you wish to target silage for specific cattle groups during next winter.
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