Effects of drastic changes in P intake on P concentrations in blood and rumen fluid of lactating ruminants.
The course of inorganic-phosphate (Pi) concentrations in blood plasma and serum were determined in lactating ruminants when P intake was changed abruptly from adequate, during a control period, to very low in a period of P depletion, and back to adequate during a period of P repletion. In each of three trials, four or three goats and, in one trial, four cows were used. In addition, the course of P concentration in the rumen fluid of three fistulated goats was studied. Pi concentrations in plasma or serum started to fall immediately with changing P intake from adequate to low, reaching a minimum plateau of less than 0.25 mM in three trials and 0.4 mM in one trial. Correspondingly, concentrations rose instantly with return of P intake to adequate, overshooting the range observed in goats during the control period and then returning to normal. P concentrations in particle-free rumen fluid declined from about 30 mM in the control period to 5.7 mM during P depletion and returned to 30 mM during P repletion, paralleling the respective course of Pi in blood plasma.
Rodehutscord
M
M
Institut für Tierernährung, Rheinischen Friedrich-Wilhelms-Universität Bonn, Germany.
Pauen
A
A
Windhausen
P
P
Brintrup
R
R
Pfeffer
E
E
D000284:Administration, Oral; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D005260:Female; D006041:Goats / Q000378:metabolism*; D007774:Lactation / Q000378:metabolism*; D010710:Phosphates / Q000008:administration & dosage* / Q000097:blood / Q000378:metabolism; D012417:Rumen / Q000378:metabolism*
D010710:Phosphates