For many dairy herds across the country, the summer has been challenging to say the least, as maximising milk yield was a struggle and turnout was delayed due to the wet weather.
Unsettled weather throughout June, July and August made grazing particularly difficult, while for others, lack of rain and resultant grass growth through June and July made buffer feeding necessary.
Recent years have seen more and more cows being housed over the summer months, as many herds have outgrown the available grazing area, and for some, it may be that grass and grazing is simply no longer seen as fashionable.
While for others, it may be the perception that grass is no longer a suitable feed for higher yielding cows with its variable quality and dry matter (DM), according to the College of Agriculture, Food and Rural Enterprise (CAFRE) dairying development advisor, Michael Verner.
CAFRE has carried out a study in south Co. Down where currently (August 2024), a lot of cows are out at grass.
The performance of those who record using the CAFRE margin over concentrates (MOC) recording is shown in the table below.
Current performance of some Co. Down herds using CAFRE MOC recording is as follows:
| Daily milk yield (L/cow/day) | 24.9 |
| Feed rate (kg/L) | 0.22 |
| Meal fed (kg/cow/day) | 5.6 |
| Milk from forage (L/cow/day) | 12.5 |
Rolling performance of the same herds from the table above:
| Annual milk yield (L/cow/year) | 8,057 |
| Feed rate (kg/L) | 0.30 |
| Meal fed (tonnes/cow/year) | 2.44 |
| Milk from forage (L/cow/year) | 2,633 |
Many factors must be considered when grazing cows but two of the biggest challenges involve:
- Achieving the highest possible grazing intakes while at the same time maintaining grass quality throughout the grazing season;
- Setting realistic performance levels that can be achieved before concentrate supplementation.
Maximising milk yield
The aim should be to offer cows upright, dense, palatable swards of grass on a consistent basis, constantly balancing grazing pressure and sward growth, according to Verner.
As per CAFRE’s dairying development specialist, ideally cows will be turned into pre-grazing covers of 3,000 – 3,200kg DM/ha to maximise intake/bite and be taken out at covers of 1,800 – 1,900kg DM/ha (6-8cm).
This equates to pre-grazing covers of 1,500 – 1,600kg DM/ha and cows to be taken out of covers of about 750kg DM/ha in the Irish grass measuring system.
If cows are offered this grass, then intakes of 15-16kg DM/head/day can be achieved, and this has the potential to support milk levels of 18 – 20L at peak for a spread calving pattern Holstein herd.
To ensure cows are allocated the correct amount of grass each day, walking and measuring grass covers on the grazing area on a weekly basis is crucial.
This enables any grass surplus or shortfall to be identified and action to be taken in a timely manner.
Sometimes both grass intakes and quality are overestimated, with the result that cows are underfed concentrates leading to a drop in milk yield and, if left unchecked, body condition.
Very often grass will be blamed but in the south Co. Down area, grassland farmers are saying that grass today can maintain the cow and produce 12-14Lof milk (some will aim higher) and are supplementing cows at a feed rate of 0.45kg/L for every litre over this.
Most will be expecting that heifers will produce 2-3L less from grass than mature cows. These levels of performance assume both good grass intakes and quality.
As the season progresses and grass quality declines, these production figures will obviously be scaled back and ending the season at 10L or less, according to Verner.
Although the south of Ireland, the north of Ireland and the UK vary in systems, it is still very important to maximise your grass growth and grass in the cow’s diet before the grazing season finishes out.
Concentrate supplementation is essential for the maintenance of the cow, but grass in the diet is going to be the real driver of milk yield and cow performance.
Verner said that “a herd of 100 cows at grass full time, could possibly be saving £120/day in diet costs compared to a similarly sized housed herd”, which proves that high yielding cows can be grazed successfully.
