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Should we focus on cutting earlier?

In the UK there is an unwritten rule that first cut grass silage is taken around 15th May when less than 50% of the crop is in ear.

The decision to cut in mid-May has a significant effect on the quality and production potential of grass silage. According to Roy Eastlake of Biotal, bringing the cutting date forward can open the door to higher production and lower feed costs. 

Year in year out first cut silage will average around 10.6-10.8 MJ/kgDM. The question is, is this good enough, and can it be improved? Given that good quality standing grass is around 12.5-12.8MJ/kgDM in early season, there appears to be potential to improve quality by targeting higher D value forage.

Table 1 compares two first cut samples this year from a farmer in Gloucestershire - one in late April and one in mid May. The swards and husbandry were identical. The difference in quality is striking with the early cut feed being 1.7MJME better. If we assume there were 500 tonnes of the forage at 30% dry matter, the early cut feed would have produced 48,000 more litres of milk or allowed a saving of over 21 tonnes of compound.

When asking farmers about why they don’t make the first cut sooner, usually three good reasons are given – concerns about not producing enough, contractor charges per acre, and risky weather conditions. When we explore these reasons further, they don’t appear to offer a good enough rationale for not cutting early.

Concerns about producing enough:

Understandably, a forage strategy needs to balance quality with quantity. There is little point having wonderful quality if you run out too soon. Cutting early does not mean producing less across the season.

Table 2 summarises a trial which was set up to explore this particular issue. The difference between early cut and conventional cutting for first cut was 10 days and the better quality feed reflects the better D-value. While first yields were reduced, quality was significantly improved. The second cut yields and quality were also better, leading to a higher total tonnage and superior quality. Overall this was worth an additional 1400 litres production per hectare.

Contractor charges per acre:

Is it worth settling for a poorer quality feed just to spread contractor charges by getting more quantity per acre? As table 2 shows, cutting early does not mean a reduced tonnage, so contractor costs per tonne would be similar and there is no real argument not to go early.

When you look at a per litre basis and using the NAAC contracting charge guide which suggests contractors typically charge £53.00 per acre, then under the conventional strategy the contracting costs would work out at 0.76ppl. For an early harvesting strategy, the contracting cost would be 0.70pp,l so cutting early can reduce contractor charges.

Furthermore, by going early you are more likely to get the contractor when you need them as you are avoiding the busiest period. This reduces the risk of poorer forage due to delays in getting the contractor on site.

Weather Risks:

Taking the first cut is always at the mercy of the weather; however modern silage machinery and innoculants can reduce the risk. Many farmers are successfully cutting in the morning and picking up late afternoon. Not only does this reduce the weather risk, it also reduces the losses due to respiration as the crop is lying in the field for a shorter time, helping ensure a better quality feed.

Provided the crop is treated with a crop and condition specific inoculant such as Biotal, fermentation quality will be high, resulting in a palatable and high quality forage. When planning silage making this year, it will pay to focus on quality - taking first cut at the leafy growth stage and before heads start to emerge. This will help to drive up forage quality and maximise production.

TABLE 1

 

EARLY SAMPLE

MAIN SAMPLE

Cutting Date

Late April

Mid May

Dry Matter (%)

35.0

32.7

D-Value (%)

75.8

65.2

ME (MJ/kgDM)

12.1

10.4

Intake potential

122.4

92.2

 

TABLE 2

 

EARLY CUTTING

CONVENTIONAL CUTTING

 

1ST CUT

2ND CUT

1ST CUT

2ND CUT

ME (MJ/kgDM)

11.8

11.4

11.1

11.3

Yield (t DM / HA)

4.2

4.1

5.5

2.5

Total Yield (t DM / HA)

8.3

8.0

Energy Harvested (MJ)

96,300

89,300

Milk Yield Potential

18,519

17,173

Contracting costs /litre. (assuming £131.00 per hect

0.70p

0.76p

 


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