Dairy farmer Henk van der Veen from Surhuizum uses slow-release urea and Protispar from Speerstra Feed Ingredients. This is 30% cheaper than additional rapeseed. He notices a slight increase in the levels.

they are just additional animal feed. When you use the rumen bypass amino acids lysine and methionine, more methionine and lysine are made available to the cow at the gut level.

This improves nitrogen efficiency and reduces nitrogen excretion. Dairy farmers can thus feed less protein without compromising on milk or protein levels.”

Tips for cutting ammonia emissions

• Reduce the crude protein in the ration. In an average ration, dairy farmers feed 16 to 16.5% crude protein, which can be reduced further. • Coordinate protein and energy in the ration (four times more rumen energy than rumen protein is optimal). This yields the highest ni- trogen efficiency and the lowest nitrogen emissions. • Offer feed with little rumen degradable pro- tein and plenty of energy, because this is a suita- ble way to reduce nitrogen excretion. • Offer (by)products with a high level of starch or sugar, such as fodder beets and grains such as crushed wheat, soda grain or potato products. • Increase the level of maize silage (low in pro- tein with a negative degraded protein balance and much starch) in the ration. This improves protein use (by capturing surplus rumen pro-

tein and stimulating milk protein production). • Offer good quality roughage and an optimal protein level through an optimal fertilising and mowing routine. Prevent heat generation and mould because this reduces protein quality and feed intake. You may want to use an ensilage agent. • Try to ensilage dryer grass, because this re- duces the breakdown of protein through the fermentation process (less soluble protein/am- monia formation) during ensilaging. This yields more intestinal digestible protein and less RCP. Only use dryer grass when you can densify well. • Feed more fresh grass instead of grass silage because fresh grass has lower RCP levels and higher intestinal digestible protein levels than silage, which reduces nitrogen emissions. • Focus on high rumen fermentation with little

protein surplus (low RCP) relative to energy in the rumen because this increases the efficiency of microbial protein formation and reduces protein losses. • Aim for fewer young stock because this re- duces nitrogen excretion at thefarm level. In- tensify calf rearing, so that heifers can calf at a younger age. • Aim for higher production per cow and a longer life span. • Improve cow health (with optimal transition management) because this improves feed effi- ciency and protein use. Less sickness also im- proves the animals’ lifespan. • Add additives to manure to limit ammonia emissions. • Add water to slurry when spreading it on fields.

▶ ALL ABOUT FEED | Volume 29, No. 1, 2021 7

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