The last couple of years have seen a keen interest in controlling the energy we use on farm to try and address the costs of fuel and electricity. But what about the cost of producing energy in our forage?

Metaboliseable energy drives milk and meat production, so looking at how much we spend on growing and preserving forage energy gives us an angle on production costs. It also leads to insights on optimising yield and quality, and the return on investment we can get from using additives to preserve forage energy.

Increased costs of growing, harvesting and preserving forage energy

Looking back to 2017 and comparing prices with today, the cost of first cut grass silage has gone from £725 to £1,250/ha. For maize silage, this rise is from around £1,000 to £1,500/ha. These values account for everything in growing, harvesting and ensiling the crop. The additive cost (depending on yield) represents between £50 and £150/ha. So, with pressure on costs, it might be tempting to stop using an additive, but we should consider what that additive brings us in reducing the cost of producing forage energy.

The forage-making process might be similar across farms, but the costs can be very different. The amount of silage wasted through losses at each stage of the process can also vary widely. And it’s these losses that are a key part of keeping forage energy costs under control.

Three factors to focus on for lowering forage energy costs

So, if it’s going to cost £1,250/ha to grow first cut silage, what can we do to feed as much energy from that spend as possible? There are three things that influence this cost the most:

1. Forage yield – getting the largest yield at the desired quality.

2. Energy content – achieving a high energy (MJ ME) forage. 3. Utilisation – preserving the yield and quality so that we lose as little as possible between field and mouth.

The impact of yield and energy content on the cost of forage energy can be seen in the tables below. These take the costs of silage making per hectare and turn them into pence per MJ of ME, so that we can see the impact of yield and quality.

mpact of yield and quality on energy cost for first cut grass silage (assuming £1,250 per ha for production and a 75% utilisation rate).

For every one tonne extra dry matter yield per ha, we reduce p/MJ by about 15%, and for every increase of 1.0 MJ ME/kg DM, p/MJ is reduced by around 10%. So, what we should be striving for is increase yield AND quality – this is a challenge, but it is possible. Approaches to achieving this are discussed in another article in this issue of KnowHow ‘Five Top Tips to Set Up Your Grass Swards For First Cut’ on page 6. It is certainly worth exploring how we can get from a grass silage energy cost of over 3 p/MJ to almost half that by striving for both forage yield and quality.

Impact of yield on energy cost for maize silage (accounting for £1,500 per ha for production, a 12.0 MJ ME energy content and a 80% utilisation rate).

For maize, the numbers indicate that energy cost reduces by 5% for every extra tonne dry matter of yield that we can achieve. Whilst maize is obviously a different crop from grass, the same principles apply when we are looking purely at the cost of energy production. However, we should remember that the maize contains a different energy profile (more starch, less fibrous energy compared to grass) and the costs of producing that energy can be very competitive against those for the grass crop.

Return on investment from your additive

Many silage additive producers and sellers express the return on investment (ROI) for using their products by comparing the cost of the additive against the amount of milk or meat that can be made from the resulting silage energy. This has some validity, but because the cost of the additive is so small compared to the income benefit when it gets to selling the end product, the ROI numbers get almost unbelievably large (like spend £1 on ‘this’ additive and get a £30 to £50 return). The problem with this approach is that there are many things that can go wrong, or right, between preserving the silage energy, feeding it out, balancing it into a ration, achieving great animal health and fertility and finally producing the milk or meat to sell.

Perhaps a more real way of looking at the ROI is purely in terms of the cost of forage energy production to the point of feeding, but not beyond. This is the utilisation part of the whole process, and this thinking focuses on the purpose of the additive and the solution it provides; to preserve the yield and nutritional quality of the fresh forage and minimise losses between ensilage and feeding.

Using a silage additive can be the difference between ‘getting it right’ and ‘getting it wrong’, where success is a well preserved and aerobically stable silage. And the difference in utilisation rate between these two can be significant, both physically and financially.

The tables below show this by looking at the energy produced in the field and the energy actually fed when we ‘get it right’, or ‘get it wrong’. Without an additive, the danger is that we lose both dry matter and energy from field to mouth, because that is what the undesirable bacteria, moulds and yeasts feed on if we don’t control them in the silage-making and feeding process.

First cut silage – Impact of preservation and aerobic stability on energy cost (assuming £1,250 per ha and 8t DM/ha yield).
Maize – Impact of preservation and aerobic stability on energy cost (assuming £1,500 per ha and 16t DM/ha yield).

These analyses show that the ROI for using the right silage additive is around 2.5:1 for the cost per MJ energy fed in both grass and maize silages – that is £2.50 back for every £1 spent. And this is without considering the fact that an appropriate additive will also bring the preservation of higher quality amino acid-based crude protein, by stopping unwanted bacteria from degrading silage protein to non-protein nitrogen.

But even considering this, we’d have to find a really good, trusted and sure-fire investment banker to get us a 250% return on investment in less than 12 months. And that’s what getting it right with a silage additive brings in reducing the cost of silage energy production and preservation.

Of course, getting it right with a silage additive means using the appropriate additive. With so many options available, a few basic pointers are:

1.Get the basics right – an additive is not a substitute for poor silage making technique. Paying attention to the detail is vital – cut the crop cleanly, will quickly, compact effectively in a clean clamp with appropriate side sheeting, sheet up overnight, use an oxygen barrier, keep it weighed down and keep the vermin away.
2. If your silage dry matter is below 28%, you can use an inoculant for preservation, but make sure it’s a tried and tested homofermentative bacteria, that will apply at least 1,000,000 bacteria per gram of silage. Stick clear of heterofermentative bacteria – they produce acetic acids and other compounds to help with aerobic stability, but in the process you will lose digestible dry matter and energy quality.
3. If you don’t want to use an inoculant and/or you have higher dry matter silage that requires to be made aerobically stable to stop heating (reducing losses in the clamp and at feed out), then go for high quality chemical salt preservatives that are proven to give a good fermentation and inhibit yeasts and moulds. Or combine a homofermentative inoculant (for preservation) with citric acid (for stability).

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