Published online by Cambridge University Press: 20 November 2017
Phosphorus (P) is a key mineral in energy metabolism and is essential in nearly every biochemical aspect of dairy cow metabolism. Therefore, P needs to be supplied in sufficient quantity to optimize animal performance. However, dairy cows only use 30 – 45% of their dietary P intake and the rest is excreted mainly in faeces. Excess faecal excretion can lead to P accumulation and saturation in the soil and filter into groundwater or remain in surface water (Tamminga, 1996), which is known to cause eutrophication. It is therefore desirable to formulate P rations according to the requirement of the animals and thereby reduce P pollution. The objective of the present study was to develop a dynamic model of P metabolism in dairy cows and use that to identify and quantify trends of P excretion as a function of P intake and investigate effects of energy supplementation on P utilisation.