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Silage season is well underway and most crops of first-cut grass have now been harvested. Many farmers that harvested grass in the past fortnight are reporting bumper yields.
Where farmers did harvest heavier grass crops, there may well be a re-think over whether a second cut is now required or not.
To help make a decision on second-cut, complete a fodder budget on how much winter fodder is in store and how much will be needed by stock. The budget should then be updated in late summer ahead of the winter.
Starting point
When drawing up a budget, work out how many cattle are likely to be on-farm this winter and the amount of silage needed to feed these animals.
Plans can always change, so when tallying up stock numbers, always err on the side of caution and overestimate by 10%. This way, you are less likely to run short of silage.
Fodder demand
Spring-calving suckler cows that are weaned and housed will typically eat 30kg to 35kg/day of silage, or approximately one tonne per cow every month. Autumn-calving cows with a calf at foot will typically eat 45kg to 50kg/day of silage, or around 1.5t per cow every month.
For every 1kg of meal fed, silage intake will reduce by around 5kg/day, which means a cow eating 2kg/day of ration will require 1.2t of fodder each month.
Spring-born weanlings on a silage-only diet will eat between 20kg and 25kg/day over winter, or around 0.6t to 0.75t/month, as will finishing cattle on high levels of concentrates.
Dry ewes of moderate size will eat 4kg to 5kg/day of silage when housed, assuming no meal is being fed.
Use the outlined values to work out how much forage will be needed this winter, or alternatively, calculate these requirements using the online calculator.
Working out silage requirements
Tally up how many cattle are likely to be on-farm this winter, grouping cattle by type. Next, calculate how much silage will be needed on a daily basis by each group.
This should then be multiplied up to cover the housing period. Factor in an additional month of silage feeding to cover early housing after a wet autumn or a late spring turnout.
Table 1 is an example of how to work out silage requirements for a suckler herd of 30 spring-calving and 15 autumn-calving cows.
Work out how much fodder is on farm?
The next step is getting a handle on how much silage is currently on-farm. Add in any silage carried over from last winter.
To calculate the tonnage in the pit, measure the length, width and average height of the clamp in metres. To convert this figure to tonnes of grass, multiply by 0.6 for grass at 30% DM.
For example, a grass clamp measuring 25m x 10m x 2m will have 300t of silage on a fresh weight basis.
Tally up any silage bales as well. A good guide to work to is 800kg for silage bales at 30% to 35% dry matter.
Does fodder supply meet livestock demand?
Compare the current tonnage of silage on-farm against demand for this winter. If there is a shortfall, then this should be used to work out how much ground to close off for second-cut.
For instance, the example herd needs 468t of silage for a six month winter period. If the pit holds 300t after first-cut, plus 50 bales of surplus grass weighing 800kg, there is a fodder deficit of 128t to make up in second-cut or by taking out more surplus grass as bales.
Closing off for second-cut
Second-cut silage made in August will have significantly lower yields than that of a June cut. Over a 40 to 50 day growing period, yields are likely to be around 5t to 7t/ac of grass depending on fertiliser rates, soil fertility and sward type.
Working at a yield of 6t/ac, the example farmer would need to close off around 22ac for second-cut to meet livestock demand.
Cost
Taking nitrogen at £650/t, spreading two bags/ac will cost £1,782. Contractor charges at £85/ac brings second-cut costs to £3,652.
Second-cut silage will require around 80 units/ac of nitrogen, 15 units of phosphate (P) and 80 units of potash (K) for soils at index 2.
Apply 3,000 gallons per acre of slurry to silage aftermath by splash plate or 2,500 gallons/ac by trailing shoe.
While nitrogen levels in slurry will be lower in a summer application, P and K will be similar. Every 1,000 gallons/ac of slurry provides around five units of P and 20 to 30 units of K.
Assuming a splash plate slurry application provides 15 units of nitrogen, topping up with 2.5 bags/ac of CAN will meet the nitrogen threshold for second-cut.
If slurry is applied with a trailing shoe, then two bags/acre of CAN will suffice.
Sulphur
Don’t forget about sulphur in second-cut silage. Choose a fertiliser with added sulphur and apply 10 to 15 units/ac to maximise yields.
Focus on quality
If cutting date for first-cut was delayed and quality is lower than normal, then target silage quality in second-cut.
As grass is unlikely to head out in an August crop, when cut in dry conditions, second-cut silage will have a high feed value.
For every four unit drop in D-Value, 1kg to 1.5kg of concentrate needs to be fed to maintain animal performance.
While having bulk in the pit will provide confidence that cattle will be fed this winter, silage cut later than normal will be high in fibre.
This will slow cattle intakes as it takes longer to digest high fibre silage. With lower intakes, cattle are getting less energy and protein for growth and milk production.
Meal costs
For finishing cattle, feeding a 66 D-Value silage instead of 72 D-Value fodder requires an additional 1.5kg/day of concentrate. Over 120 days, this costs an extra £72/head for a finishing ration costing £400/t.
Across 50 cattle, the additional meal fed to offset the drop in feed value comes to £3,600. If the steers were eating 25kg/day of high-quality silage made as second-cut, each animal consumes 3t over 120 days or 150t for the group. At a yield of 6t to 7t/ac, the 22ac of second-cut would provide enough high-quality forage for the finishing steers, which, as outlined in step four, will cost in the region of £3,600.
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