5. Conclusions
Reduction in dietary P concentration from 3.4 to 2.3 g
P/kg DM reduced DMI, milk yield, milk protein yield and
plasma Pi concentration, and increased serum concentration of the bone resorption marker CTX, but did not affect
serum concentration of OC in early lactation. Reduced
dietary P concentration from 3.4 to 2.8 g P/kg DM did
not affect DMI or milk production in early lactation. Dry
matter intake and milk yield was not affected by dietary P
concentration in late lactation. It is not possible to reduce
dietary P concentration to 2.3 g P/kg DM in dairy cows in
early lactation without compromising DMI and milk production as cows were not able to maintain DMI and milk
yield for more than 6 weeks after parturition at this
dietary P level despite mobilization of bone P during the
period. The results indicate a potential for reducing dietary
P concentration in early and late lactation to 2.8 g P/kg DM
without effects on performance, but this level of dietary P
might not allow for repletion of bone P mobilized in early
lactation