EFFECT OF 1-ALPHA-HYDROXYCHOLECALCIFEROL ON CALCIUM AND PHOSPHORUS CONCENTRATION IN GOAT MILK

Twelve small black Moroccan goats were used during the second month of their fourth lactation to compare the influence of an increase in pla sma calcium (Ca) concentration induced by Ca infusion or by 1 alpha-(O H) D-3 injection on milk Ca concentration. in four goats, Ca gluconate i.v. infusion (7 mg Ca kg(-1) body weight) increased plasma Ca concen tration from 10.3 +/- 0.04 to 13.3 +/- 0.04 mg dl(-1) (P < 0.05) witho ut changing milk production and milk Ca and inorganic phosphorus (Pi) concentration. In five goats, 1 alpha-(OH) D-3 i.m. injection (3 x 0.5 mu g kg(-1) body weight) increased plasma Ca and 1,25-(OH)(2) D conce ntrations from 10.7 +/- 0.03 to 13.2 +/- 0.05 mg dl(-1) (P < 0.05) and from 147 +/- 5 to 764 +/- 12 pg ml(-1) (P < 0.001), respectively, wit hout changing daily milk production, Daily Ca and Pi secretion through the mammary gland increased from 1.22 +/- 0.09 g and 1.08 +/- 0.05 g before treatment to 1.45 +/- 0.05 g (P < 0.05) and to 1.30 +/- 0.05 g (P < 0.05), respectively, No significant variation in plasma or milk C a or Pi concentrations was observed in three control goats, These resu lts indicate that in goats, as in cattle, plasma 1,25-(OH)(2) D concen tration may regulate Ca and Pi secretion through milk.