Lower grass growth rates a major risk to feed security and costs

Following a brief recovery in May, farmers across the country are again feeling a real pinch in grass growth in the last fortnight. In some cases, growth has halved in a week and silage has again been included in milking herd diets. It will come as no surprise therefore that Ireland figures show year-to-date grass DM production running approximately 0.8t DM/ha behind the average year.

So far, 2024 has been a problematic grass growth year, with delayed grazing, slurry and nitrogen applications having an impact on grass production.

Figure 1 shows the weekly grass growth for this year and the last five years and their mean. The current grass growth is disappointing and is just ahead of grass demand.

Current grazing situation

Table 1 shows the current assessment of grass supply on farms within PastureBase Ireland. Average grass growth is 54 kg DM/ha, while grass demand is slightly lower at 52kg DM/ha. Soil moisture and lower than expected temperatures are the primary cause, although N supply to the sward may be a factor on some farms also. Grass supply is below normal of farms with a grass demand >3.5cows/ha on the grazing platform. While grass growth is likely to recover in the coming week, it is very important not to let farm cover slip too low in the mid-season period.

Long-term impacts

Longer term, the effects of reduced pasture growth rate will be lower silage stocks and higher feed costs.

A reduction of 1.0 to 1.5 tonnes DM grown per hectare annually may not sound significant. However, when the full costs of balancing the deficit with purchased feed are added up, the scale of the effect becomes very clear.

To illustrate in Table 2, we have taken an example dairy farm of 54 ha grazing platform plus an outside block of 20ha used for making silage and grazing heifers. For simplicity, we assumed a 10.5t DM annual growth on the outside block across each scenario.

At 13.5 tonnes DM grown on the grazing platform, the whole farm is self-sufficient for silage, though the total surplus is small at less than 10 tonnes DM, no reserve. Purchased concentrate comes in at around 930kg or 5.5 cent per litre.

If we step back to 12 tonnes DM grown, the picture changes significantly. In this scenario, the farm is no longer able to make enough silage inside the farm gate meaning about 70t DM silage (or 280-320 tonnes fresh weight) must be sourced on the open market. Meal feeding rates also increase by 130kg per cow or about 22 tonnes as fed annually. Total feed costs rise by 43% in this case to 7.9 cent per litre.

Inevitably, a further drop in growth rate (back to 10.5 tonnes DM) has a similar but more severe effect. Here, the deficit in silage becomes 500 to 550 tonnes as fed. Filling this gap is a big management challenge for a herd of this size, and certainly leaves no room for delayed action. In terms of meal feeding, the annual cost rises to €92,500, which is about 90% higher than the 13.5t grown scenario.

Remember, the extra meal in Scenario B and C is being fed to compensate for grass deficits and will not result in any additional milk yield (milk solids yield could be more likely to fall in fact due to extra silage in the diet). Therefore, it will add directly to feed costs.

Comparing feed costs for Scenario A and C, there is a difference of five cents per litre - this is a massive increase in costs considering that stocking rate, cow type and annual milk solids yield is relatively constant. If meal costs per tonne were to increase, or if purchased silage were sourced at higher input costs (land rental, contractor charges, fertiliser etc.), then the gap would be greater still. Granted there will be a saving on the cost of ‘silage not made’ of about €3000-7000, but the net increase in cost of lower annual growth rates remains very significant.

Over the last two to three years we are seeing this trend slowly emerge on some farms inflated feed costs for no increase in output. While high unit tonnage costs of meal and fertilizer have added to cost inflation, it is very likely that an underlying reason for ‘cost creep’ is reduced pasture growth and utilisation.

Taking action to mitigate feed deficit risks

Weather conditions in 2024 have certainly had a negative impact on grass growth and utilisation beyond farmers’ direct control; however, farmers will still have to deal with the reality of lower feed reserves for the second half of the year in advance of next winter. This is a big physical and financial challenge. As always, taking earlier action reduces risk and stress, and will probably reduce cost in the long run: