feed crop soil rumen
Article by Dr George Fisher and Dr Dave Davies

The word ‘efficiency’ has been used in livestock production for many decades, but it’s increasingly regarded as the elixir to solve all ills. But what does ‘efficiency’ mean and can it really be the solution to reducing costs of production, protecting the environment and reducing our dreaded carbon use and emissions?

Efficiency means…
… getting more out for what you put in. And it works across everything we do:
• More milk produced for fewer working hours to improve labour efficiency.
• The desired weight and conformation of beef cattle for less concentrate feed input.
• Higher crop yields for less fertiliser inputs.

So, the link with profitability is obvious, especially in our current climate of rising and volatile input costs.

Improving efficiency is a win-win, because…
… if we are using fewer inputs for the same, or more milk and meat output, then we are using less carbon per kilo of product we sell off-farm. Two of the big-ticket items in the carbon footprint of any farm are purchased concentrate feeds and manufactured fertilisers, so if we can be more efficient with these (basically reduce their use), then our carbon footprint markedly improves. The World Dairy Federation has reported that the carbon footprint of milk production can be reduced by 40% through efficiency measures alone – and that’s without recourse to renewable energies and planting trees.

Being more efficient with inputs also helps to reduce emissions to the air, like ammonia, as well as lowering losses to watercourses, like nitrates from fertilisers and manures.

So, put the profit, carbon and environment issues together, and efficiency is worth more than a passing thought. And we’ve already made huge steps. For example, according to DEFRA’s annual survey of fertiliser use, the amount of manufactured fertiliser nitrogen applied to grassland in the UK has reduced by half since the 1990s – and this is with no reduction in overall meat and milk production. So, farmers in the UK have already done the efficiency thing and can do even more.

Efficiency can be difficult because…
… we have come so far down the road that it is not now simply about looking at one input in isolation, but looking at all inputs in an integrated whole farm way, from soil to crop to the ruminant, and tracking efficiency along the line of production to make the gains.

So, let’s track a nutrient through the production process and see where we are with regard to efficiency.

Are we efficient in nitrogen use?
Take 100kg of nitrogen (N) applied to a crop as manufactured product. Table 1 (below) shows the efficiencies of use at each stage.

The rather crude calculations in the table do not take into account that some of the nitrogen from the fertiliser will go into the soil reserve for growth in future seasons and that much of the nitrogen at the feeding stage will also get into slurries and manures which will be recycled. We also have to consider that we are dealing with ruminants, which are biologically inefficient in how they use energy and nutrients.

But the thought logic shows that it’s no use addressing efficiency at one point in the process and ignoring the rest. We have to address efficiency at every point of the production process to get the maximum benefit of our inputs.

So, this brings us to ask, what can we do at each stage to optimise our performance, remembering that this will benefit our profitability, carbon use and impact on the farmed environment? What does each part of the process need from us as managers?

Feed the soil

As we are continuously told, it all starts with the soil. And this is really about the basics. So, in order to get the soil to present available nutrients and water for crop growth, we must:
✔ Achieve and maintain a soil pH of 6.5.
✔ Make sure the soil is not compacted (we want the bugs in the soil to work for us and they require air).
✔ Achieve and maintain soil index 2 for phosphate (P) and 2+ for potassium (K).
✔ Don’t allow soil magnesium to exceed index 3
(which means magnesium limes are ‘out’).
✔ Keep feeding the soil with organic matter from slurries and manures (the soil bugs will like it, the soil will hold more water and have a better structure which will reduce compaction).

How much of the nitrogen we spread gets into the products we sell?
Efficiency example taking 100kg nitrogen from soil to animal product
Table 1: Efficiency example taking 100kg nitrogen from soil to animal product
Feed the crop

If we can combine great soils with optimum crop management, then we can get to that 90% efficiency of fertiliser nitrogen use in Table 1. To get the crop right, we must:
✔ Do the basics of weed, pest and disease control.
✔ Choose varieties of grass and crops that suit the production system and carry the latest and most efficient genetics for yield and quality.
✔ Have a field-by-field nutrient management plan that we use and update regularly.
✔ Make sure sulphur is applied in the fertiliser programme (in the form of plant available sulphate), even on heavier soils.
✔ Use soil reserves and slurries/manures as the base of the nutrient plan, only topping up with manufactured fertilisers as required.
✔ Optimise the value of slurry by using a product like Digest-It from Kelvin Cave Ltd that will provide a consistent slurry product with available and organic nutrients.
✔ Get the slurries/manures analysed so we know how much N, P and K they are supplying.
✔ Use a little-and-often approach to nutrient applications – the right nutrients, at the right time, in the right place and in the right quantities will improve efficiency and optimise yields and quality.

From an animal perspective, this, of course, is only half the story. If we are preserving the crop for later feeding, then ensilage and preservation has an enormous impact on the quantity and quality of the harvested crop that we present to the nutrition phase.

wheat field
Feed the rumen

The rumen needs a balanced diet containing many things, the major two being energy and protein. These two components need to be supplied in a balanced way for the rumen microbial population to maximise its growth efficiency and supply the ruminant with most of the nutrition it requires. Remember, feed the rumen bacteria and they will feed the ruminant. The energy comes from a mix of sugars, starches and cell wall or fibre which are degraded in the rumen at different rates. Likewise, the protein, or more correctly nitrogen, comes in various forms from non-protein nitrogen like urea through to intact protein. Home-grown feeds can supply many of these nutrients but if we do not preserve them correctly, we will have deficits. For example, a slow fermentation in the silo will result in a large amount of protein being broken down into ammonia, which will then require a high level of sugar for the rumen bacteria to be able to grow efficiently. However, the same slow silage fermentation will have used up all the sugar in wasteful process and so supplementation at feed-out with molasses may be the only option.

When home-preserving crops for ruminant feed there are three key areas to focus on to improve efficiency: field, silo at filling and silo at feed-out. As with everything else in this cycle from soil to milk and meat, each step is linked to overall efficiency, and improving efficiency will reduce costs, reduce environmental impact (be that air, soil or water) and improve milk and meat output.

Feed the rumen bacteria and they will feed the ruminant.
Feed the rumen bacteria and they will feed the ruminant.

The key word in terms of preserved feed production is losses and how you can reduce them and how that improves quality. Many people think dry matter losses are visible, and whilst some DM losses are visible many are invisible and reducing these is critical to improving efficiency. Invisible DM losses use the most digestible part of your forage, namely the sugar and protein, and convert them to products with lower value such as acetic acid and ammonia, or no value such as CO2, oxides of nitrogen known as NOx gases, or water. The processes causing these losses start the moment the crop is cut in the field and do not stop until they are consumed by the animal. Quoting Jacob Bronowski (The Ascent of Man), ‘Man masters nature not by force but by understanding. This is why science has succeeded where magic failed: because it has looked for no spell to cast over nature’. Thus, by understanding the science we can use the best approaches to control these losses. 

Preserving home-grown feeds
If we can combine harvesting at the maximum nutritional value with optimising yield and reducing post-harvest/mowing losses, we will improve nutritional value and reduce losses, be that direct or indirect losses. Remember it’s yield of utilisable nutrients, not yield of dry matter that is the key

In the field

✔ Mow when the crop is dry.
✔ Leave a 7.5-10cm stubble, for grass/clover/lucerne. This improves the efficiency of wilting and crop regrowth and leaves the less digestible stem with the highest numbers of undesirable organisms in the field.
✔ Wilt rapidly by spreading the crop and tedding within 2-4 hours. Sugars and proteins are metabolised by both the plant and aerobic micro-organisms in the field. Rapidly wilting reduces these losses.
✔ For maize, adjust stubble height depending on forage requirement versus quality requirement. The bottom 15-25cm of maize is relatively undigestible high fibre which, if included, reduces the energy density and starch content of the whole crop ensiled.
✔ Hit the target DM for the forage/feed being preserved.
✔ Adjust chop length for crop dry matter and maturity.
✔ Ensure the material harvested through the forage harvester ends up in the trailer ie: don’t overfill trailers or harvest high DM forages such that once the forage is chopped finely, it blows away in the wind!

In the clamp

You take control of the preservation process, rather than leave it to nature. By understanding the processes involved, we can dominate the natural populations of predominantly undesirable microorganisms and plant enzymes which would otherwise reduce the nutrient value of preserved feeds and increase methane emissions from livestock once fed. Controlling these processes includes using the correct forage additives alongside proper silo management.
✔ Speeding up the fermentation to stop degradation of protein and energy (sugar) in the forage/feed. Once a stable pH has been reached, plant and microbial processes cease degrading the nutrients. Homofermentative inoculants are the only inoculants that will do this. Food grade preservatives also do this by inhibiting the undesirable microbial populations allowing the desirable lactic acid bacteria to dominate the preservation process.
✔ Side sheet – preferably with 1m along the floor of the clamp.
✔ Compact quickly but properly. Unlike in the field, where soil compaction is bad because it reduces the activity of the beneficial soil aerobic microbes, in the clamp, compaction is a prerequisite of good preservation, as aerobic microbes are the enemy of silage. So, do not use dual tyres and reduced air pressure in wheels and ideally use a SilaPactor to speed up filling and improve density, with the additional bonus of reduced fuel use.
✔ Hermetically seal the clamp. Again, air is the culprit of poor silage quality both in terms of preservation and aerobic stability at feed-out. Side sheets should overlap the top sheet by 2m. Use oxygen barrier sheeting systems and ensure a completely airtight seal against the wall, also sealing and weighing down the ramp with gravel bags touching all the way round.

At feed out

If everything is done as stated, the risks of feed-out losses are much lower. However, it is still important to manage feed-out properly.
✔ Roll back the top sheet as little as possible and secure to the top of the silage with gravel bags touching across the full width of the clamp.
✔ Remove any visible top waste (if you followed the rules there should not be any). If you have
top waste, take it away from the vicinity of the clamp as the microbes in the spoiled silage will blow onto the silage feed-out face and start eating the nutrients here. Ideally weigh any top waste and calculate the value of your losses. A harsh lesson for next year!
✔ Maintain a cleanly cut feed-out face by ensuring cutting implements are sharp and tines on sheer grabs are maintained properly and at the right length.
✔ Ensure it takes no more than three days to traverse the whole face.
✔ Monitor aerobic deterioration in the clamp or in the feed-trough. The only additives that will not compromise preservation quality and improve aerobic stability are combinations of homofermentative silage additives with the correct level of food grade preservatives such as sorbate or citrate. Or food grade preservatives on their own.

In conclusion

Remember, to get the complete picture you must finish every part of the jigsaw. Often in farming, things go wrong or aren’t quite as good as they should be so, to quote the computer scientist, Newton Lee, ‘Man-made environmental disasters force nature’s hand to unleash its fury on humankind’. Whilst he was referring to environmental disasters, it is often possible to see where nature has given the farmer a beating!

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