For most farms, fertiliser is in the ground on their silage blocks and, for autumn calving herds and those that are winter milking, fertiliser would have been targeted in late March to avail of an early cutting date.
Winter milking can be an expensive way of milking cows as, quite often, if silage quality is not optimum, milk production is heavily reliant on meal feeding or other sources of feed such as maize silage, soya hulls, or beet.
While many farmers aim to maximise their winter milk contract, doing so should be through quality first cut silage as much as possible to keep the costs of production to a minimum.
The aim for first cut silage is to produce high yields of highly digestible silage that is well preserved and, the longer it is left into May, the more fibre present as the silage bulks up.
Subsequently, as first cut silage cutting date is delayed, second cut silage will also be delayed and yields reduced, leading to an expensive winter diet for the cows.
Winter milking silage
When the silage crop is cut in early May, the silage will be more digestible with less fibre present, while the second cut of silage has a chance to be heavier, leading to a cheaper winter diet based on a silage capable of supporting higher intakes.
By reducing the amount of stem and fibrous content in the silage, the more the cow will be able to eat.
The great weather over the spring gave farmers a good chance of getting the silage ground spread with fetiliser and slurry early and, with the mild conditions continuing with some rainfall, an early May cut should be very achievable.
Cutting first cut silage between May 5-10 is ideal for winter milk systems and will allow sufficient time for farmers to achieve high yields of second cut silage in late June into July.
Cutting in the first week of May is essential on many farms to achieve that 75-80% dry matter digestibility (DMD) silage as a lot of silage ground may have been closed off since September or October and quality can deteriorate rapidly the longer it is left.
However, if the sward was grazed down tightly in recent weeks before slurry and fertiliser application, then a cutting date of May 18-20 may be sufficient to achieve quality milking silage to support production.
The following table is a guideline on grass silage DMD for different classes of dairy stock:
Dry cows
Spring cows in milk
Growing heifers
Winter cows in milk
DMD %
68-70
72
72
75
Typical first cut date
Early June
Late May
Late May
Mid May
First cut yield (t DM/ha)
5.5-6
5-5.5
5-5.5
5
There is a clear indication that the DMD percentage decreases the later the harvest date, with the tonnage/DM/ha increasing as the harvest date is delayed.
First cut silage should not be about bulking up silage supplies, and while it is perceived that pushing back first cut silage cutting date will bulk supplies, but in fact, it is only going to take away from the bulk of the second cut while deteriorating first cut silage quality.
Bulking up silage supplies is very important but not at the expense of quality, as bulking up supplies should be done over a number of cuts rather than one cut at a time.
