Pathophysiological effects of low dietary phosphorus in pigs

The homeostasis of inorganic phosphate (P-i) is regulated by parathyroid ho rmone (PTH), 1,25-dihydroxy-vitamin D (1,25(OH)(2)D), and P-i itself in the intestine, kidney, and bone in all the mammalian species studied. Determin ations of the serum concentrations of PTH, 1,25(OH)(2)D and osteocalcin wer e done in 82 southern Romanian Landrace pigs originating from three herds w ith dietary P-i deficiency. Serum P-i concentrations were negatively correl ated with those of 1,25 (OH)(2)D. In lactating animals and sucklings, the l inear relationships between P-i and 1,25(OH)(2)D were not present. Serum P- i concentrations were positively correlated with those of PTH. In lactating animals and young pigs, the linear relationships between P-i and PTH were not evident. PTH and 1,PS(OH)(2)D concentrations were negatively correlated . The serum concentrations of 1,25(OH),D and osteocalcin were positively co rrelated. Milk P-i concentrations ranging from 3.10 to 7.49 mmol/L were cor related positively with urinary Pi concentrations ranging from 0.26 to 11.3 7 mmol/L. In conclusion, similarly to other species, P-i homeostasis is ach ieved in pigs by feedback mechanisms between P-i, PTH and 1,25(OH)(2)D and osteocalcin production is induced by 1,25(OH)(2)D. The effect of lactation on P-i homeostasis remains to be explored. (C) 2001 Harcourt Publishers Ltd .