The relationship between the quality of grass on Irish farms and farm profitability cannot be underestimated as it is well documented that as grass utilisation increases, net profit increases.
Germinal’s Dr. Mary McEvoy highlights that farmers now need to focus on producing tonnes of high-quality grass, in order to maximise animal performance and sward utilisation.
According to Mary: “The measure of quality in grass is expressed by its dry matter digestibility (DMD) and the higher the quality of the grass, the higher in energy it is.”
When grass is highly digestible, it tends to have a lower fibre content; therefore it is less filling and the animal is likely to eat more of it.
Grass quality will drive animal performance, with a 1-unit increase in grass digestibility, increasing milk yield by 0.24L/cow/day.
“For a 100-cow herd, across a 30-day period, it is easy to see how this becomes a significant figure very quickly,” states Mary.
In addition, research has shown that grass which is higher in quality and digestibility will lead to higher milk protein percentages.
“During the mid-season period, many farmers will notice a drop in milk protein percentage. Producing high-quality grass will once again play a huge part in maximising the potential of the animal to produce high milk solids,” says Mary.
In contrast, poor-quality, low DMD grass is lower in energy and contains more fibre, thus making it bulkier. This grass therefore takes up more room in the rumen, resulting in the animal eating less of it.
As a result, milk production is limited as an animal in the peak of her lactation will be less likely to receive enough energy to reach her milk potential. On-top of this, lower-quality swards are more difficult for the animal to graze out, due to more stemmy material or a less palatable sward.
This reduction in graze-out or sward utilisation will have a negative impact on the next grazing round and as a result, the sward will need to be topped in an attempt to limit the build-up of stemmy material in the sward.
The importance of grass mixtures
“Variety choice has a big impact on the quality of the sward,” explains Mary. There are huge differences in grass quality between varieties on the Recommended List and the Teagasc Pasture Profit Index (PPI).
The PPI demonstrates the difference between the highest-quality variety (AberGain, +€56/ha/year) and the lowest-quality variety (-€38/ha/year); a difference of €94/ha/year on the quality sub-indices alone.
An excellent graze out on a field of AberGain
When reseeding, most farmers will sow a mixture containing three to four varieties. When it comes to grass mixtures, the optimum mix is a combination of diploids and tetraploids, and virtually all grass seed mixtures are formed on this basis.
While tetraploids are noted for their higher quality and palatability and hence, higher animal performance and grass utilisation, there are two diploids which display similar properties.
For grazing mixtures in particular, it is critically important that high-quality diploids and tetraploids form the basis of the mixture.
Table 1 below explains the difference between diploid and tetraploid grasses. AberGain is the highest-quality tetraploid and the highest performing variety overall on the 2019 PPI.
AberChoice is the highest-quality diploid and highest-value diploid overall on the 2019 PPI. To see the Teagasc Pasture Profit Index 2019 click here
“What you sow on your farm today will be expected to perform over the next eight to 10 years,” said Mary.
“It is therefore worth choosing a grass seed mixture that contains the highest-quality varieties available to ensure you maximise animal intake and performance and the palatability (utilisation) of your sward for years to come,” concludes Mary.
Table 1
Further information
For more information on grass seed mixtures click here
