Influencing rumen microbes improves nitrogen efficiency

Feed additives can increase nitrogen efficiency and reduce ammonia emissions. Proper rumen functioning, the right protein-energy balance in the rumen and more intestinal digestible protein also help.


Feeding potato pulp as an addi- tional source of energy and Pro- tispar, which contains essen- tial oils, tannins and saponins from plants, im- proves protein use.

xperts agree that improving nitrogen utilisation at dairy farms requires a comprehensive approach. Dairy farmers can reduce ammonia emissions by tak- ing several measures. In addition to optimising dairy

rations, improvements in roughage crops, rearing youngstock and transition management are all options. Feed additives still play a limited role, but more independent research may change this view.

What causes high nitrogen excretion? Jan Dijksta, senior cattle feed lecturer at Wageningen Univer- sity & Research, explains that when too much protein is di- gested in the rumen, nitrogen excretion will also be too high. Secondly, when there is too little energy in the cows’ rations, the conversion of amino acids into milk protein will be subop- timal and nitrogen will disappear into the urine. “On average,

75% of the ration consists of roughage. Good quality rough- age that provides a lot of energy is the basis for successfully cutting nitrogen emissions. The final steps in this process can be additives,” says Dijkstra, who points out that relatively lim- ited independent research has been done on the effects of additives on dairy farming. Dijkstra divides the additives into seven groups (see Table 1).

Measures affect nitrogen emissions Wilfried van Straalen, researcher at Schothorst Feed Research, says there are various measures that affect nitrogen emis- sions (Table 2). “Additives can contribute to this, but don’t ex- pect any miracles,” he says. “However, 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 cal- culation shows that there is a shortage, and that this is the first limiting nutrient.”

Limited number of feed additives Feed additives that are supplied directly to cattle farmers to improve nitrogen efficiency have limited availability. Agrinu- trition is a Barents subsidiary, which is a wholesaler in raw ma- terials. Its consultants directly supply products to dairy farm- ers. “We decide on the composition ourselves because we have extensive knowledge of raw materials,” says Agrinutrition category director Bianca Meijerink. “We’ve been developing feed additives for years 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.”

Meeting environmental demands According to Jan Speerstra, owner of Speerstra Feed Ingredi- ents, additives can help to meet ever-stricter environmental demands. They can also help to achieve a better return on investment. “We keep speaking of ‘additives’, when in fact,

6 ▶ ALL ABOUT FEED | Volume 29, No. 1, 2021


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