If an inevitable loss of 1.2 g P per kg DM intake were assumed (Spiekers et al., 1993)
then the cows in the present trial would have been losing approximately 28 g of P per day at
23.3 kg DMI. The total faecal excretion was approximately 43 g. Thus, 15 g of P would have
been either undigested or the result of a homeostatic regulation to excess P. The contribution
of each of these two fractions was not determined in the present experiment. Nevertheless,
15 g excreted would imply an effective utilisation of dietary P of 0.75, if it was assumed
that 28 g of P would have been lost under all conditions.