Pathophysiological Effects of Low Dietary Phosphorus in Pigs

SUMMARY meostasis of inorganic phosphate (Pi) is regulated by parathyroid hormone (PTH), 1,25-dihydroxyvitamin D (1,25(OH)2D), and Piitself in the intestine, kidney, and bone in all the mammalian species studied. Determinations of the serum concentrations of PTH, 1,25(OH)2D and osteocalcin were done in 82 southern Romanian Landrace pigs originating from three herds with dietary Pideficiency. Serum Piconcentrations were negatively correlated with those of 1,25(OH)2D. In lactating animals and sucklings, the linear relationships between Piand 1,25(OH)2D were not present. Serum Piconcentrations were positively correlated with those of PTH. In lactating animals and young pigs, the linear relationships between Piand PTH were not evident. PTH and 1,25(OH)2D concentrations were negatively correlated. The serum concentrations of 1,25(OH)2D and osteocalcin were positively correlated. Milk Piconcentrations ranging from 3.10 to 7.49 mmol/L were correlated positively with urinary Piconcentrations ranging from 0.26 to 11.37 mmol/L. In conclusion, similarly to other species, Pihomeostasis is achieved in pigs by feedback mechanisms between Pi, PTH and 1,25(OH)2D and osteocalcin production is induced by 1,25(OH)2D. The effect of lactation on Pihomeostasis remains to be explored.