Want more milk from home-grown feed? Then maximising energy in your grass and ‘locking-in’ as much as possible when you turn it into silage are key steps. New research points the way.
A key foundation for milk production is the amount of metabolisable energy (ME) available to the cow, says Volac silage scientist Philip Jones.
There is a relationship which says it takes about 5.3MJ of ME for her to produce one litre of milk.
And if you want to insulate your business against volatile feed prices, providing as much of this ME as possible from home-produced forage and silage is a ‘no brainer’, Mr Jones says.
“Here in the UK we are blessed with being able to grow good grass, so it makes sense to make the most of this asset.
“An interesting way to view this is the amount of ME you can make available from your grass per hectare.
“We know that new leys are more productive than old ones, but in addition to growing nutritious grass, with silage generally fed for half the year, it is also important to ‘lock-in’ as much of this nutritional value as possible when turning it into silage.”
Achieving this is a multi-stage process, says Mr Jones, which is what the Cut to Clamp educational resource is all about (see ‘Better silage’ panel).
However, two particular steps attracting increased interest for improving silage are cutting grass at the optimum growth stage and including a proven additive as an integral part of the conservation.
Elaborating on these, Mr Jones says if cutting is delayed until after heading, the digestibility of grass, which determines its ME, falls by 0.5% per day.
Similarly, animal feeding trials have shown conserving silage with Ecosyl additive has significantly improved ME, from 10.6 to 11.2MJ/kg dry matter (DM).
Indeed, further research showed feeding silage preserved with Ecosyl also led to cows producing an extra 1.2 litres of milk/cow/day.
Now, this latest Volac research has taken this a step further by focusing on the progressive technique of cutting grass younger and taking more cuts per season using a multi-cut system, as well as on conserving this potentially high quality forage.
Mr Jones says: “Theoretically, we know that multi-cut silage should offer several nutritional advantages.
As well as being higher in protein, younger grass should also be more digestible, therefore naturally higher in ME.
“Accordingly, this latest twoyear research project, which was conducted in a real farm situation, examined these quality parameters.
By measuring yield, we were then also able to derive a figure for how much extra ME/ha the multi-cut system could potentially deliver.” Pointing to the findings, Mr Jones says fresh grass from the five-cut, multi-cut system was clearly of higher nutritional quality than from the more conventional three-cut approach.
Average digestibility from the multi-cut was three D units higher, at 72.7 compared to 69.7, which equated to it delivering an extra 0.5MJ/kg of ME.
In addition, crude protein content was also almost 3% higher, at 16.7% versus 13.9%.
Mr Jones says: “When overall yield was measured, we found five cuts also delivered an extra 0.92 tonnes/ha of DM in total, with a DM yield of 16.92t/ha.
“When this extra 0.92t/ha of DM was multiplied by its higher energy content, this was equivalent to it providing an extra 18,582MJ/ha of energy over the season [see Figure 1].
“If it takes 5.3MJ of energy to produce one litre of milk, this means the multi-cut had the potential to deliver an additional 3,506 litres/ha.
“Even after subtracting the extra contractor costs, if you take milk at 25ppl, this would still leave you about £333/ha better off.” As well as demonstrating extra energy potential of the fresh multi-cut grass, new research also shed light on improving its preservation, says Mr Jones.
While the higher protein content of multi-cut is a benefit, nutritionally it can also contribute to buffering of the fermentation.
In addition, shorter intervals between cuts means less time for slurry to dissipate before the next cut is taken, which increases the risk of slurry bacteria in the silage.
The combination of high buffering and the action of slurry bacteria can lead to DM losses.
Mr Jones says: “With these challenges in mind, a further part of the research examined how these might be mitigated, by comparing how the fermentation proceeded in multi-cut samples without an additive, compared to where Ecosyl was used.
“Results showed that not only was the fermentation slow without the additive, with pH levels never reaching those achieved in the treated silage even 90 days after ensiling [Figure 2], there was also a big increase in enterobacteria numbers, the bad bacteria often associated with slurry, where no additive was used [see Figure 3].
“Ultimately, nearly 10% of the DM was lost across all cuts of the untreated silage, and there was evidence of protein being broken down [see Figure 4].
“Where Ecosyl was used, not only was fermentation faster, with the pH falling rapidly [see Figure 2], which is key for inhibiting bad bacteria, but enterobacteria numbers were between 100 and 100,000 times lower [see Figure 3], and the average DM loss was almost halved [see Figure 4].
There was also evidence of better preservation of protein.
“In summary, it was clear multi-cut grass offers the potential to ‘grow more milk’ by providing a higher output of ME/ha, but it does need conserving properly, and treating with Ecosyl certainly helped to achieve that.”
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