The results of this study show that there is a linear
relationship between P intake and faecal P excretion,
when feeding lactating cows 44–142 g of P per day.
For each gram of increased P intake, 0.86 was
excreted in faeces. Furthermore, apparent P digestibility decreased with increased P intake. The variation
of P in faecal output was substantial between days,
and total collection of faeces should therefore
continue for at least five consecutive days when
studying P balance.