Influencing rumen microbes improves nitrogen efficiency
Feed additives can increase nitrogen efficiency and decrease NH3 emissions. Proper rumen functioning, the right protein-energy balance in the rumen and more intestinal digestible protein can also help.
Experts agree that improving the nitrogen use at dairy farms demands a comprehensive approach. Dairy farmers can decrease ammonia emissions by taking several measures. In addition to optimising dairy rations, improvements in roughage crops, rearing youngstock and transition management are possibilities. Feed additives still play a limited role, but more independent research can change this.
What causes high nitrogen excretion?
Jan Dijksta, senior cattle feed lecturer at Wageningen University & Research, explains that when protein digestion in the rumen is too high, nitrogen excretion will be too high as well. Secondly, when there is too little energy in the cows’ rations, the conversion of amino acids into milk protein will be suboptimal and nitrogen will disappear into the urine. “On average, 75% of the ration consists of roughage. Good quality roughage that provides a lot of energy is the basis of successfully decreasing nitrogen emission. The final steps in this process can be taken with additives,” says Dijkstra, who points out that relatively limited independent research has been done into the effects of additives on dairy farming.
Different measures effect nitrogen emissions
Wilfried van Straalen, researcher at Schothorst Feed Research, says different measures affect nitrogen emissions. “Additives can contribute to this, but do not expect any miracles,” he says. “A recently published meta-analysis shows that tannins do have a positive effect on nitrogen use.”
He emphasises that the results of additive enhancement are strongly dependent on the type of ration and the quality of roughage and concentrates. “Adding slow-release urea and rumen bypass amino acids is only useful when the ration calculation shows that there is a shortage, and this is the first limiting nutrient.”
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Agrinutrition is a Barents subsidiary, which is a wholesaler in raw materials. Its consultants directly supply products to dairy farmers. “We decide on the compositions ourselves because we have extensive knowledge of raw materials,” says Agrinutrition category director Bianca Meijerink. “We have been developing feed additives for years now based on market needs and practical research. Our motto is: “Farmers are the scientists. They prove that our products work and keep them on the market.”
Additives for environmental demands
According to Jan Speerstra, owner of Speerstra Feed Ingredients, additives can help to meet the ever-stricter environmental demands. They can also help to reach a better return on investment. “We keep speaking of ‘additives’, where in fact, they are additional animal feed. Using the rumen bypass amino acids lysine and methionine, more methionine and lysine are made available to the cow at a gut level. This improves the nitrogen efficiency and decreases nitrogen excretion. Dairy farmers can thus feed less protein without compromising on milk or protein levels.”
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Targeted feeding of rumen bypass amino and fatty acids
Speerstra is very positive about feeding rumen bypass amino and fatty acids to dairy cows. “In pig and poultry farming, synthetic amino acids in feed are already used with considerable success. Feeding cows based on which specific amino and fatty acids they need concentrates the ration, improves nitrogen efficiency, decreases methane emissions, and contributes to more well-balanced milk fat. We are not yet ready for this in the Netherlands. In the United States however, they have been working with this for a longer period.”
Feed additives are not cheap. Prices vary from € 125 to € 500 per 100 kilogrammes. “You cannot compare these prices with those of regular feed.
Feed additive prices
Feed additives are not cheap. Prices vary from € 125 to € 500 per 100 kilogrammes. “You cannot compare these prices with those of regular feed,” says Eric Heemskerk, director at Ingenieursbureau Heemskerk. “They are used in very small quantities and they can save a lot on other expensive sources of protein, such as soy or rapeseed.”
Optimising the rumen function
“By properly feeding a cow, you actually feed the rumen bacteria,” says John Vonk, product developer at Ingenieursbureau Heemskerk. The company sells a slow releasing rumen nitrogen in the Netherlands, Belgium, and Germany. “By keeping the amount of urea in the rumen constant and minimal, you synchronise the protein and carbohydrate supply, which makes rumen bacteria grow better. Especially the bacteria digesting cellular walls, making the cow digest the ration better. If there is enough available energy, the cow uses the feed protein better.”
The minimal dosage of 100 grammes per cow per day can replace 600 to 1,000 grammes of protein rich feed, such as soy or rapeseed meal, and it decreases nitrogen excretion with at least 2,5%.
Controlling rumen processes
“Controlling rumen processes is crucial for proper protein use,” says Speerstra. “The rumen is responsible for about 70% of a cow’s protein supply. The composition of a microbial protein, formed in the rumen, is the most suitable for a cow to convert into milk protein. Essential oils inhibit the activity of hyper ammonia producing (HAP) bacteria and the digestion of protein in the rumen. This increases protein use and decreases ammonia emissions.”
Additional energy at gut level
Rumen bypass fats yield additional energy at a gut level and the energy-protein balance in the ration. “This improves protein use,” says Robert Meijer, manager marketing and communication ruminants at ForFarmers. He emphasises that a protein surplus in the cow rumen, especially from fresh grass and grass silage, forms the biggest nitrogen loss. “A proper rumen function and a proper coordination of energy and protein in the rumen is priority number 1 for high nitrogen use. Make sure you have the proper composition of roughage, by-products and additional concentrates, so the total ration fits and protein from roughage and regular feed is maximally used.” Meijer also thinks that more room is needed to feed additional forage maize in rations that are rich in grass and that feed additives may contribute to improving nitrogen use.
ForFarmers conducts research into additives that hold practical promise based on scientific research. Meijer does not want to say which ones. “We test the effect of additives under Dutch circumstances,” he says. “Specific buffers, yeasts and B vitamins can further improve rumen fermentation, because they stimulate bacteria that break down cell walls. These bacteria in particular capture much protein surplus from grass silage and therefore considerably improve protein use.”
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