In 2017–2018, most farms experienced severe winter conditions followed by a summer drought that reduced annual grass growth and forage supplies by one quarter.
To cope with such shocks, Dr. Joe Patton a dairy specialist with Teagasc and Siobhan Kavanagh, regional manager Waterford/Kilkenny for Teagasc – recommend that farms build a rolling silage reserve of 400kg dry matter (DM) per livestock unit.
That’s the equivalent of two bales per head, or about one month’s feeding for a mature cow.
This level of reserve represents a compromise between feed security and the cost of making and storing the additional feed.
Forage reserve
In practice, developing a reserve will happen through a combination of better silage management and strategic purchase of reserves, where required.
Having a forage reserve means that your options are much better in difficult years.
Where the daily deficit is <10% on a DM basis, low fibre (NDF) concentrate products, based on native cereal and protein sources, can be readily used.
On the other hand, larger proportional deficits mean you have to buy in high fibre by-product feeds.
Much of this product type is imported, with all that entails. Increasing forage grown per hectare on your land is usually the cheapest means of building forage reserves.
Many farms will increase their forage production by getting their fertiliser and liming right. This should be tackled before considering other options
Management effects on silage yield – soil fertility
Silage yield and quality are often considered as competing objectives. However, a good base of soil fertility and a well-managed reseeding programme will deliver high yields at the quality required across the year.
On farms with poor soil fertility, silage cutting often gets delayed to build adequate yield.
However, if soil fertility is improved, then the crop will reach target yield much earlier, leading to better quality and an improved recovery for second cut.
Should first cuts be delayed for bulk?
It is vital to consider the yield of forage DM across the year as a whole, not just from a single cut.
The effect of different first cut dates on total grass silage DM and forage energy (UFL) yield per hectare, in a two-cut system with a fixed second cut date in late July, was assessed.
There was no advantage in total DM production to delaying first cut due to poor yield at second harvest.
Worse still, first cut silage was lower in dry matter digestibility (DMD) and not suitable for growing cattle or calves, milking or suckler cows.
Delaying second cut further, for the ‘later’ first cut swards, would have reduced availability of autumn after-grass and negated any silage yield benefit.
In fact, many farms which delayed first cut in 2017 experienced great difficulty in salvaging second cut crops in late August and September, which contributed to the silage shortage.
Low soil fertility may exacerbate this problem due to slower recovery and increased delay to second cuts.
From a cost perspective, delaying first cut would not result in significant dilution of land charge (due to similar total DM yield per hectare), while contractor costs would be similar (particularly on a bale silage system).
Management decisions around first cut silage yield should be made on the basis of meeting DMD targets and improving annual grass tonnage per hectare, rather than focusing solely on the bulk of an individual cut.
Forage cost
At recommended volumes and a moderate forage unit cost of €160-180/t DM, a standard dairy herd would need to invest €80-€140 per cow for no increase in milk revenue.
However, unlike purchased feed that is used within the year, the reserve is retained as stock inventory and so is largely profit-neutral.
The cost of building a feed reserve highlights the need to examine the economics of
increasing herd scale based on conserved forage and concentrates.