Only a fraction of our grassland is reseeded annually, despite recommendations to target 5-8pc of a farm for new ley every year.
With less than 20pc of Irish farmers measuring grass on a regular basis, under-performing pastures are able to stay under the radar.
But an increasing amount of research from Teagasc highlights just how much lower output paddocks are costing both beef and dairy farmers.
Putting a value of 26-30c/kg on concentrates, a kilogram of grass drymatter is approximately four times less, at just 7.8c/kg, while silage is still half the cost at 15-18c/kg.
Put another way, if a farmer can replace 1kg of concentrates with 1kg of grass over the course of a 210 day grazing season, the savings come to €42 per cow.
Better again is getting grass swards that extend the grazing season, with every extra day at grass worth €1.54 per suckler cow.
In the case of the dairy cow, the savings are even greater, at closer to €2.10 per day in the autumn, and €2.70 daily in the spring (due to the higher feed demand for spring calving cows in the case of the latter).
Suddenly, it becomes obvious that there are massive potential savings to be harvested from getting really productive pastures in place. Getting the 100 cow dairy herd out to grass a week earlier in the spring and a week longer in the autumn is worth a massive €3,360.
The combination of both - extending the grazing season and utilising more grass during the year - adds up, because each additional tonne of grass drymatter utilised will increase net profit by €160/ha.
The other factor that is becoming clearer over time is the impact of pasture digestibility on profitability.
Again, Teagasc research shows that a 1pc increase in drymatter digestibility results in a 5pc increase in performance. That's an extra 2 litres of milk daily from a 25 litre cow, or €60 per day in extra milk sales for a 100 cow herd.
In drystock, the impact is similar. A 5pc fall in digestibility results in over 250kg extra meal requirement over the course of a 150 day beef finishing period. In the case of lambs, a 5pc decrease in digestibility results in an extra 25kg/hd being fed during a 70 day finishing period.
So the case is clear: getting more high quality grass into animals pays dividends.
There are several factors that feed into maximising grass output and quality, including soil fertility, the reseeding programme, variety selection and grazing management.
"It's no good going to the expense of reseeding and putting in the highest yielding varieties if the farmer isn't optimising soil fertility and the utilisation of the grass being produced," said Dr O'Donovan.
"There are a couple of key things that the top utilisers of grass are routinely doing. They achieve a high number of grazings per paddock annually - at least 8-10 grazings. They also are proactively managing their pastures.
"So if the weather takes an unexpected turn, they react by speeding up rotations, taking out silage bales, increasing stocking rates, introducing meal temporarily, and so on. Of course, they can't do this without knowing exactly how much grass they are producing on a weekly basis. That's why we stress the importance of measuring grass so much," he said.
Soil fertility is another issue that farmers are struggling to manage, given that a shocking 90pc of grassland is at sub-optimal levels of fertility. But even on farms with t p management, maintaining soil fertility is a big challenge.
A case in point is the Greenfield demonstration farm, where soil indexes for phosphorus (P) have actually fallen over the last three years. In 2012, over 85pc of the farm was at the target index of 3 or 4 for P. That had fallen to less than 60pc by 2014.
The biggest falls in P and K were in paddocks that were producing most grass, especially if part of that grass was being removed as silage. Management believe that the decision to save on fertiliser costs by applying zero P in 2012 was a likely factor.