Gains from improved milk prices could be eroded by high costs of nitrogen fertiliser (N) unless dairy farmers focus on producing good grass silage this season, says silage expert Ken Stroud of Volac. This includes learning lessons on cutting date flexibility, he says.
“As one of the cheapest feed sources, good silage is likely to be pivotal to farming profitably,” says Mr Stroud. “But there are extra pitfalls this year.
“Cutting back N fertiliser because of its cost could cause grass yield and quality to suffer. Alternatively, applying extra slurry to replace N will increase risks from slurry bacteria. Plus, we saw last year the importance of adjusting cutting date to navigate unusual weather.”
In response to various challenges, Mr Stroud offers five key tips:
Recognise the value of your silage
Do recognise the contribution that silage makes to maximising milk from forage, stresses Mr Stroud, it’s not just bulk. “It’s not enough to grow quality grass. You need to minimise losses in its nutrients when turning it into silage.
“Typically, dry matter (DM) losses in grass silage are about 10%, but they can be 25% or higher. So follow best practice silage production and fermentation methods. Cutting grass younger improves digestibility and protein content, while conserving with a proven additive can halve DM losses and preserve more energy and protein.
“If unsure how well your silage normally ferments, check previous silage analyses. You want a ratio of lactic acid to undesirable volatile fatty acids (VFAs) of at least 3:1.”
Adapt to the weather
Last year’s unexpectedly cold April and wet May, which delayed grass growth and then harvest, underlined the importance of being flexible with silage cutting dates, says Mr Stroud. Farmers who didn’t seize an early first-cut often didn’t get another chance until June.
“Cutting early not only allows a silage cut to be ‘banked’, it also encourages fresh regrowth. Cutting earlier does lead to more cuts. But cutting five times in our research produced grass on average 3 D units higher in digestibility and almost 3% higher in crude protein than cutting three times, and yielded 0.92 t/ha extra DM. This year there are added reasons for cutting earlier: to clear old grass growth from the mild winter, and because cutting back N could cause grass to head earlier due to stress.”
Mitigate slurry risks
Applying extra slurry to replace some bagged N, or cutting silage at shorter intervals, increases the risk of poorer fermentation and DM losses due to enterobacteria in the silage, says Mr Stroud, making it important to manage this risk.
“Apply slurry as soon as possible after harvesting to allow it more time to dissipate. Also, consider dilution to encourage it to wash into soil quicker, and apply by trailing shoe or injection to keep it off leaves. To improve fermentation, rapid wilting becomes more important. As too does wilting to at least 30% DM and using an additive: enterobacteria numbers in silage made using Ecosyl have been 100,000 times lower than in untreated.”
Rapid wilting to the correct %DM is also important to reduce the breakdown of sugars and proteins that occurs between cutting grass and ensiling it, says Mr Stroud.
“To reduce wilting time, ted straightaway after cutting. In a trial on grass cut on a warm, dry July day, cutting at 10am and tedding immediately resulted in grass reaching the target 30% DM in just 4.5 hours, compared with 24 hours when left in rows. Rapid wilting to the correct DM should minimise losses at all stages of silage making.”
Keep contractors informed
Cutting grass before heading is vital for top silage quality, says Mr Stroud, so keep your contractor informed in advance of when you will need them, and especially if planning to cut earlier or more often this year. “A benefit of cutting earlier is that contractor availability is often better, which reduces the risk of grass quality passing its peak due to delays.”