27 August 2024

Variation in weather having an impact on grass growth and utilisation

Joseph Dunphy, Grass10 Team, discusses challenges faced by dairy farmers this August due to unusual grass growth and grazing conditions, resulting in the need for increased supplementation and strategic grazing management to prepare for autumn.

August is normally a more relaxed time on dairy farms with major jobs such as breeding & main crops of silage completed. However, this August has seen huge variation in grass growth and grazing conditions that have brought continued challenges in what has been a very difficult grazing season so far in 2024.

Figures from PastureBase Ireland show that growth rates have been 15% behind compared to the long term average for August. Depending on location both lack of rainfall or excess rainfall have been a major cause. Farms in the southern part of the country struggled with soil moisture deficits throughout August & have only received adequate rainfall in the last 7 days. Cooler weather has resulted in growth rates on these farms not getting the “bounce” that they would like to increase grass supply.   Farms further north in the “Border Midlands, West” region have received excessive rainfall over the last 10 days leaving some parts of the farms saturated and particularly on heavy soil farms, cows having to be housed at night. In both cases, supplementation has had to be increased to meet herd demand and we see this through the stagnation of Average Farm Covers (AFC) on PastureBase Ireland at a time of the year where we expect it to be increasing. On some of these farms, 100% of the winter feed requirement has not been met yet so silage eaten now will have to be replaced by purchased feed.

PastureBase National Growth Curve

However, there is time for a favourable September yet if weather forecasts improve.  There is 20% of the total grass growing season still remaining on your farm. Therefore, it is important to achieve the objectives of autumn grazing management to manage costs and performance in autumn 2024. The main target currently is to extend rotation to build grass supply on the farm for the next month.

Many farmers will not achieve the targets set out in the table below due to the difficult growing conditions. The target now should be to set up a 30 day grazing rotation for September. If you have a 30 Ha grazing platform, allocate 1 Ha per day & fill the balance with meal & silage (silage has a greater impact on reducing grass intake). Measuring weekly during September on PastureBase Ireland (PBI) is essential to keep an eye on AFC and Cover/cow.

On most farms all of the milking platform should be available to the milking herd by now. Any remaining young stock should be removed to out farms to maximise pasture availability in the cow’s diet during the autumn. Every day at grass is worth over €3 per cow per day in this period.

If you are behind target in early September on your farm use supplement such as silage, concentrate or zero-grazed grass to build AFC while grass growth and soil temperatures are still high. Reacting later in September will result in more supplement having to be fed.

Autumn Grazing Targets