There are reports on “liquid manure tourism” or unwanted increases in nutrients in water bodies. One supposed cause is allegedly excessive commercial fertiliser application. In principle, however, (mineral) phosphorus sources such as monocalcium phosphate are finite resources. They should be used selectively based on the latest knowledge. The new Fertiliser Ordinance provides a legal framework in this matter.
Effects of phosphorous on dairy cows
If a dairy cow is fed phosphorous, it responds with increased phosphorus secretion in its faeces. This has an impact on the farm's nutrient balance and may increase the farm's agricultural land requirements or the quantity of manure which needs to be exported.
Phosphorous supply has an equally dramatic effect on the dairy cow itself. Phosphorus is a central element for numerous bodily functions, metabolic processes and bone formation, so poor rumen fermentation can be expected if there is a lack of phosphorus in rations. This causes a dramatic decrease in microbe activity in the rumen, a decline in ration digestion and a reduction in microbial protein production.
Consequences of under supply of phosphorous
Visible consequences of phosphorous deficiency are undigested feed particles in faeces and a reduction in feed intake, milk yield, fertility and health condition. Plant-based feedstuffs have very different phosphorous contents to some extent. Moreover, a large part consists of phytate-bound phosphorus; this can only be absorbed as phosphate after enzymatic degradation in the rumen by local microbes and by ruminants in the small intestine.
In the past, this knowledge often meant that the ration composition needed to be determined based on total or gross phosphorus with appropriate "safety allowances", in the form of monocalcium phosphate, for example. This was the only way to compensate for extreme fluctuations in the feed-specific phosphorus contents and digestibilities. These may have otherwise caused ration-related declines in performance due to a phosphorus deficiency in the rumen or small intestine.
Phokus calculation tool
Phokus is a ration calculation tool which optimises ration compositions based on the phosphorus which dairy cows can digest in the intestine and which also takes into account the phosphorus requirement for rumen microbes. This makes it possible to provide a targeted reduction in the gross phosphorus content in the overall ration.
Taking the farm-specific nutrient and mineral analyses of the silages used as a basis, the AGRAVIS production consultant can use Phokus to calculate needs-oriented, phosphorus-optimised dairy cattle production while taking into account potential phosphorus savings in rations. To do so, appropriate Lakto, Laktaria, balance and VitaMiral mineral feed are incorporated into the ration composition. This new type of ration calculation saves on costs for feed, reduces excess phosphorous in the ration on a lasting basis and contributes to future-oriented milk production.
