Significant increases in grass energy yield/ha, and, improved milk from forage, are possible if the results from two research projects are anything to go by.

However, regardless of which production system is selected, it is maximising milk from forage that is the bottom line in profitability, when taking into account work on the value of sward quality and a separate study on multi-cut silage, carried out by Germinal and Volac respectively.

Speaking at a recent industry briefing, SRUC professor of dairy nutrition John Newbold, said analysing data from different dairy systems – ranging from an intensive high-output system, to a more extensive grazing-based system, and farms in the middle ground – feed was the biggest business cost across all farm types.

Moreover, in all three cases, the most profitable 25% of farms were the ones that produced more milk from forage – whether grazed grass, silage or a combination. Describing forage as 'natural capital', his advice for profitability was to grow better grass, make better silage and to use the silage better.

Germinal GB’s Ben Wixey referenced a new study now underway at the Germinal Research Station, where the metabolisable energy (ME) yield/ha value of perennial ryegrasses is being compared with the energy potential from weed grasses that predominate in deteriorating swards.

“Grass leys do deteriorate with age, which means lower value weed species replace the perennial ryegrasses that were selected and sown at the time of reseeding,” he said.

“Despite this knowledge, it’s a fact that reseeding rates remain stubbornly low, and that all too many swards contain a significant proportion of weed species that will affect productivity.

“At our Melksham facility we are measuring and analysing the common weed grasses alongside modern perennial ryegrasses, so that we are able to calculate the impact of declining sward quality and therefore the value of routine reseeding."

Mr Wixey added that taking the second cut silage scenario, trials revealed that a new reseed would potentially contribute around 2000 litres/ha more milk from forage than a five-year-old ley with just half of the perennial ryegrass remaining.

Furthermore, if the life of the old ley was extended to 10 years, with just 25% perennial ryegrass remaining, then the difference rises to 3410 litres/ha.

"If we apply a milk price of 27p/litre, this roughly equates to an extra £500-£1000/ha in additional milk from forage, simply by maintaining sward quality," he said.

With more dairy farmers now making multi-cut silage – where grass is cut younger and more frequently as a way of improving milk from forage – Volac scientist Dr Mark Leggett said new farm-based Ecosyl research had examined the potential of multi-cut to deliver extra milk.

Results confirmed that grass from a five-cut system was indeed more nutritious than from a more traditional three-cut approach – with an average digestibility (D Value) of 72.7 versus 69.7, and delivering 0.5 MJ/kg more energy. Crude protein content was also almost 3% higher.

Over the season, the multi-cut grass also yielded 0.92t/ha more dry matter (DM). When combined with its higher energy, this equated to it providing an extra 18,582 MJ/ha, Dr Leggett pointed out.

“Based on 5.3MJ being required to produce a litre of milk, this means this particular multi-cut system had the potential to deliver an extra 3506 l/ha of milk,” explained Dr Leggett.

“At a milk price of 25p/litre, this is equivalent to an extra £877/ha earned, which would still leave you about £333/ha better off after deducting the extra contractor costs.”

But while multi-cut grass has the potential to unlock more milk from forage, this is only half the picture, as these nutrients still need to be conserved within the silage.

“Although multi-cut offers nutritional benefits, it can be more challenging to ensile,” he explained. “It's higher protein can contribute to buffering of the fermentation, while shorter cutting intervals can mean less time for slurry to dissipate, and so increased risk of slurry bacteria being present, which can produce DM losses.

“A further stage of our research found that when multi-cut was allowed to ferment without an additive, not only was the fermentation slow, with enterobacteria, the bad bacteria often associated with slurry, continuing to grow, but the average DM loss was nearly 10%.

"By comparison, average DM loss was virtually halved when treated with Ecosyl additive, and there was clear evidence of better protein preservation," added Dr Leggett who concluded that multi-cut offers the potential for more milk from forage, but cannot be realised without careful ensiling.