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Interview: Jan Dijkstra on using feed to reduce emissions

Jan Dijkstra, animal feed expert at Wageningen University & Research (WUR), sees many opportunities to reduce nitrogen, ammonia, phosphate and methane through the proper use of feed.

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Jan Dijkstra, animal feed expert at Wageningen University & Research (WUR): ‘On average, cattle farmers feed too much protein. Feed companies should assume the role of feed expert and consultant and should focus less on selling as many tons of product as possible. Only suggest feeding high levels of protein when it’s actually necessary.’

Cattle farmers (supported by consultants) often play it too safe when it comes to feed concentrates, says Jan Dijkstra. They’re afraid of lower milk production, so they tend to over-feed their cows. The surplus protein finds its way into the animal’s urine in the form of nitrogen where it evaporates as ammonia. “On average, farmers feed 16.5% raw protein in the dairy ration. This can be brought down to 15.5% without any loss of milk production, which leads to a reduction in ammonia emissions of nearly 10%. That’s a huge difference.” He takes the Irish approach as an example. This country’s law dictates that derogation participants can only use feed concentrates with less than 15% raw protein next year. with no exceptions. Dijkstra: “This is not possible in the Netherlands, unfortunately. We do not have a government agency like the Irish one that checks the maximum amount of protein or can make exceptions to this rule.”

On average, farmers feed 16.5% raw protein in the dairy ration. This can be brought down to 15.5% without any loss of milk production...”

What role can the compound industry play?

“There are opportunities for feed concentrates. Low-protein feed concentrate is an option, but you should always look at it in connection with protein from grass (silage). The quality of feed concentrates will become a focal point, especially the protein quality. Durability and quickly or slowly degradable fibres come into view here. In the future, using specific amino acids in protein may also come into play.”

Photo: Koos Groenewold
Photo: Koos Groenewold

Can the problems with nitrogen/ammonia, phosphate and methane be solved by adopting an ideal feed strategy?

“That would be fantastic, but it mostly just creates conflicts. A measure that does work is feeding a silage maize ration. This is low in protein, has better nitrogen efficiency, with less nitrogen and ammonia emissions and less phosphate. It also has lower methane emissions than grass.”

A silage maize ration is favourable, but the exemption actually curbs silage maize cultivation by increasing the grassland cultivation norm from 70% to 80%.

“This is a shame, but the exemption exists because of the amount of nitrate in groundwater. The nitrate concentration under maize land on sandy soil is twice as high as on grassland. You must then consider the best option. Nitrogen efficiency has deteriorated in the last four years due to a reduction in maize cultivation because of exemption and drought. The increase to 80% should be reversed or it should become even lower than 70%. A combination of protein from grass and starch from maize delivers higher nitrogen efficiency and is better for the environment. When you cultivate the soil properly and cultivate a good catch crop, you can achieve a lot with modern silage maize cultivation.”

1% extra fat in the feed leads to 5% less methane."

You also recommend mowing grass early with a dry matter yield between 2,000 and 2,500 kilograms per hectare. That solves 2 problems, right: optimal feed and less methane?

“Young grass goes hand in hand with low-protein feed. Protein from young grass is by far the cheapest and its quality comes close to the protein quality of feed concentrates. Mowing and feeding every day is ideal, optionally adding silage maize. The grass should not grow above 15 cm for a pasture cut. Take your grass level meter into the field several times a week. That way you can achieve a reduction in methane emissions of 30%, which is a big step for the environment. However you do it, do not let the grass grow for too long, because this leads to a reduction in feed quality. Roughage quality is the foundation for feeding well.”

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Shouldn’t the government reward such a decrease in methane?

“That will be the case some day, but reducing nitrogen is the first point on the government’s agenda. This can be done through compound feed or roughage (or both) to get a ration that is lower in protein. The rule here is: what doesn’t go in, doesn’t come out. It can be quite hard to manage. On average, cattle farmers feed too much protein. When milk production doesn’t run smoothly, feed consultants often suggest putting more protein in the ration, because it increases milk production. When you don’t know the underlying cause, you just advise using more protein. The chances are that production will increase and the customer will be happy.”

Would that not exacerbate the nitrogen and methane problems?

“The whole sector needs to be convinced that it should get to work to fix this. When the sector itself doesn’t spring into action, the government will intervene forcefully. Enter a covenant about protein in compound feed and about methane, which is what happened with phosphate in the Netherlands. Feed companies should assume the role of feed expert and consultant and should focus less on selling as many tons of product as possible. Only suggest high protein when it’s actually necessary. Advise as well as possible, fitting the cattle farmer’s need for an optimal operating result but also fitting society’s need to protect the environment. Keep the importance of the sector within the socially accepted image in mind: without a ‘license to produce’, cattle farming deteriorates.”

Mitigating methane production in the rumen
Several feeding strategies can be adopted to reduce methane production in the rumen. In this article, however, the focus is on the use of fat supplements in the animal’s diet.

The DSM feed supplement Bovaer is being developed right now for reducing methane. Adding this methane blocker leads to 20% less emissions. You have conducted research on this in Wageningen. What’s the status of this miracle agent?

“The good thing about Bovaer is that it’s persistent. For many other methane blockers, long-term effectiveness is still a question mark. The European Food Safety Authority must decide about its admission now. This should come through somewhere at the end of 2020, but the focus on corona research may cause delays.”

That’s impressive: 20% less emissions. Why not implement this right away?

“It costs cattle farmers more money, without delivering extra milk yield in return. If the government wants to reduce methane, it can either do so through punishing or through rewarding farmers. In this case, large environmental benefits can be obtained through rewards. The greenhouse gas production per kilogram of milk can be specified per farm, which the government can use a reward or punishment standard.”

Can the compound feed industry do more?

“Of course, for example by adding extra fat to feed. 1% extra fat leads to 5% less methane. Go to roughly 7% (not too high). More fat does mean more expensive feed. Choose unsaturated fatty acids. Rumen-resistant saturated fat can have a negative impact on cheese processing.”

How about phosphate?

“In the Netherlands,thanks to the covenant, phosphate excretion has already decreased significantly. It can be cut even more, by millions of kilograms. In the Netherlands, every kilogram of milk contains 1,010 milligrams of phosphorus on average. The numbers indicate that this can be reduced by at least 3 kilograms per lactation. The fear of a phosphorus shortage is almost always unnecessary. The challenge for the compound feed industry lies in low-phosphorus feed. Recent research indicates that low phosphorus during the drying-off period can help to prevent low calcium levels in the blood in the first day/days after calving. It helps to prevent ketosis in much the same fashion.”

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And ammonia?

“Nitrogen in urine, which results in ammonia emissions, is largely avoidable. Ensure a proper balance between rumen-degradable protein and rumen-degradable carbohydrates (for energy). This leads to less nitrogen in the cows’ urine. In the future, it will become even more important to prevent the disbalance between energy absorbed from the gastrointestinal tract and absorbed amino acids, leading to less nitrogen in the urine. Farmers can manage this by using compound feed and by watching the durability of nutrients, depending on the feed system.”

What are the opportunities for using other raw materials?

“Low-protein raw materials are almost always low in phosphorus, too. There is much variation between these raw materials. Soybean meal for example has a better balance between protein and phosphorus than rapeseed meal. There are opportunities for feeding starchy by-products such as potatoes. Grains also work very well, such as crushed wheat and soda grain, which is produced by ‘unlocking’ the wheat with caustic soda. You can process different protein sources, such as field beans, seaweed and algae, but also insect protein (which is not formally admitted yet, ed.). We should close the mineral cycle locally or regionally, for example by using waste flows. We also need to keep developing knowledge about how to use nitrogen and phosphorus as sparsely as possible.”

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Does choosing durable raw materials mean more expensive feed?

“Cheap can also mean expensive in the long run. You need to keep the eventual value of the milk and meat in mind. Precise feeding is necessary, no matter what.”

How does that work?

“It’s a challenge and requires a great deal of customisation to feed the animals individually. It will be possible in the future with all kinds of sensors, but we’re not quite there yet. Larger farms can work with production groups, which is a great step towards refining even more. Managing feed in the parlour is easiest and it’s most effective for nitrogen, ammonia and methane. It gets more difficult for animals put out to pasture. You can’t add much with compound feed, so you need to focus on your grass management. Making sure that the cows eat high-quality roughage is important.”

Cows are exceptionally good at converting protein into milk

Micro-organisms in the rumen mean that a cow can eat feed that humans cannot consume. Jan Dijkstra calculated how well cows do this compared to humans. He looked at products containing protein that humans could also have eaten. The cow’s yield is 3.5 times as high. Because of this yield alone, it’s attractive to use even more residual products from human consumption. Dijkstra also mentions the reintroduction of animal meal, which is currently prohibited because of BSE. A large part of it is usually burned or used in biogas installations. “What a waste,” notes Dijkstra. Thanks to modern DNA techniques, it’s easy to prevent animals consuming meal derived from the same species. “Start allowing it in poultry and pig feed and thus avoid, for example, large imports of soy.”