Contact/s:
Rocco Lioy
rocco.lioy@convis.lu
Reducing Ammonia Emissions by Optimizing the Feed Rations of Dairy Cows
Continental Europe
- Ammonia emissions
- Optimization of protein content in ration
- Protein autonomy
Thematic Areas
Production System/s
Summary for Practicioners on the Main Finding(s)/Innovative solution(s)
The practice of optimizing crude protein intake in dairy cows (See Figure 3, Measure 16 in CFD AMM library) is a key lever for reducing both ammonia and GHG emissions.
As part of the AUTOPROT project (www.autoprot.eu), it was established that a considerable proportion of the protein produced and fed on the farm is not utilised by the dairy herd. This unutilised protein is of great importance because it increases the risk of ammonia losses. The AUTOPROT project also showed that farms with a high degree of self-sufficiency in protein (protein self-sufficiency) have a lower proportion of unutilised protein. It can be shown mathematically that the unutilised protein corresponds to the luxury consumption of protein by the dairy cattle.
It is known from the literature that high crude protein levels in cattle rations generally lead to increased excretion of nitrogen in the form of urine. It is the urine that is responsible for the escape of ammonia, as urea, the main component of urine, is very quickly converted into ammonia. If the crude protein in the rations is well adapted to the animals’ requirements, the animals excrete more nitrogen via faeces, which contributes significantly less to ammonia emissions.
Thanks to a study by Sajeev et al. (2017), it also became known that the potential for reducing ammonia losses in cattle by reducing by 1% the crude protein surplus in the ratio is 17% of the total output.
A key point is the definition of a target value for ration optimisation. According to experts, crude protein levels in the rations of dairy cows can be reduced to a level of 15% in dry matter without any loss in milk yield. In the opinion of the experts, a crude protein content of 14% in the ration is sufficient for young cattle. Based on these considerations, the CONVIS farms in the AUTOPROT project were able to achieve potential savings in NH3 emissions of around 10 kg of nitrogen per ha through ration optimisation. Of these savings, 90% came from ration optimisation for dairy cows alone.
Summary for Practicioners in Native Language
Die Optimierung der Rohproteinaufnahme bei Milchkühen (siehe Abbildung 3, Maßnahme 16 in der CFD-AMM-Bibliothek) ist ein wichtiger Hebel zur Verringerung der Ammoniak- und Treibhausgasemissionen.
Im Rahmen des Projektes AUTOPROT (www.autoprot.eu) wurde festgestellt, dass ein beträchtlicher Teil des Proteins, das im Betrieb erzeugt und verfüttert wird, von der Milchviehherde nicht verwertet wird. Dieses nicht verwertete Eiweiß ist von großer Bedeutung, denn es erhöht die Gefahr von Ammoniakverlusten. Im Projekt AUTOPROT wurde ferner gezeigt, dass Betriebe mit einem hohen Selbstversorgungsgrad an Eiweiß (Eiweißautarkie) einen niedrigeren Anteil an nicht-verwerteten Eiweiß aufweisen. Man kann rechnerisch darstellen, dass das nicht verwertete Eiweiß dem Luxuskonsum an Eiweiß durch das Milchvieh entspricht.
Aus der Literatur ist bekannt, dass hohe Rohproteingehalte in der Ration von Rindern im Allgemeinen zu einer erhöhten Ausscheidung des Stickstoffs unter Form von Harn führen. Dabei ist gerade der Harn dafür verantwortlich, dass Ammoniak entweicht, da der Harnstoff als Hauptbestandteil des Harns sehr schnell in Ammoniak umgewandelt wird. Wenn das Rohprotein in den Rationen gut am Bedarf der Tiere angepasst ist, scheiden die Tiere den Stickstoff vermehrt über Kot aus, der deutlich weniger zu den Ammoniakemissionen beträgt.
Dank einer Studie von Sajeev et al. (2017) wurde weiter bekannt, dass im Rindviehbereich das Reduzierungspotential der Ammoniakverluste durch Verringerung um 1% des Rohproteinüberschusses in der Ration bei 17% des Gesamtausstoßes liegt.
Ein wesentlicher Punkt ist die Definition einer Zielgröße für die Rationsoptimierung. Nach Ansicht von Experten lassen sich Rohprotein-Gehalte in der Ration von Milchkühen bis auf ein Niveau von 15% in der Trockensubstanz ohne Einbußen in der Milchleistung absenken. Für das Jungvieh ist nach Ansicht der Experten ein Rohproteingehalt in der Ration von 14% ausreichend. Aus diesen Überlegungen konnte für die CONVIS-Betriebe ein Einsparungspotential an NH3-emissionen über die Rationsoptimierung von rund 10 kg Stickstoff pro ha. Von diesen Einsparungen stammen 90% allein aus der Rationsoptimierung der Milchkühe.
Longer Description
The practice of optimizing crude protein intake in dairy cows (See Figure 3, Measure 16 in CFD AMM library) is a key lever for reducing both ammonia and GHG emissions.
As part of the AUTOPROT project (www.autoprot.eu), it was established that a considerable proportion of the protein produced and fed on the farm is not utilised by the dairy herd. This unutilised protein is of great importance because it increases the risk of ammonia losses. The AUTOPROT project also showed that farms with a high degree of self-sufficiency in protein (protein self-sufficiency) have a lower proportion of unutilised protein. It can be shown mathematically that the unutilised protein corresponds to the luxury consumption of protein by the dairy cattle.
It is known from the literature that high crude protein levels in cattle rations generally lead to increased excretion of nitrogen in the form of urine. It is the urine that is responsible for the escape of ammonia, as urea, the main component of urine, is very quickly converted into ammonia. If the crude protein in the rations is well adapted to the animals’ requirements, the animals excrete more nitrogen via faeces, which contributes significantly less to ammonia emissions.
Thanks to a study by Sajeev et al. (2017), it also became known that the potential for reducing ammonia losses in cattle by reducing by 1% the crude protein surplus in the ratio is 17% of the total output.
A key point is the definition of a target value for ration optimisation. According to experts, crude protein levels in the rations of dairy cows can be reduced to a level of 15% in dry matter without any loss in milk yield. In the opinion of the experts, a crude protein content of 14% in the ration is sufficient for young cattle. Based on these considerations, the CONVIS farms in the AUTOPROT project were able to achieve potential savings in NH3 emissions of around 10 kg of nitrogen per ha through ration optimisation. Of these savings, 90% came from ration optimisation for dairy cows alone.