EFFECTS OF WHEY-PROTEIN ON CALCIUM AND BONE METABOLISM IN OVARIECTOMIZED RATS

We studied the effects of whey protein (WP) from cow's milk on calcium and bone metabolism in ovariectomized (OVX) rats. Six-week-old female Sprague-Dawley rats were ovariectomized and fed a low-calcium diet (0 .03% Ca, 0.3% P) for 4 weeks. The OVX rats were divided into three gro ups and subjected to two experiments: Exp. 1, Cont group (20% casein, 0.3% Ca), WP (1%) group (19% casein, 1% whey protein, 0.3% Ca) and Low -Ca group (20% casein, 0.03% Ca); and Exp. 2, Cont group (20% casein, 0.3% Ca), WP (1%) group (19% casein, 1% whey protein, 0.3% Ca) and WP (2%) group (18% casein, 2% whey protein, 0.3% Ca). The rats were fed e ach experimental diet for 4 weeks. The final body weight, weight gain, food intake and food efficiency showed no significant difference betw een the Cont and WP (1%, 2%) groups in Exps. 1 and 2. There were no si gnificant differences in the calcium balance, serum ALP or serum calci tonin levels between the Cont and WP groups in Exp. 1. But the breakin g energies of the WP (1%, 2%) groups were higher than those of the Con t groups in Exps. 1 and 2. As for the amount of calcium, phosphorus an d magnesium in the femur, there were no significant differences betwee n the Cont and WP (1%, 2%) groups; however, the amounts of total amino acids in the femur of the WP (1%, 2%) groups were higher than those o f the Cont groups in Exps. I and 2. The amounts of proline and hydroxy proline in the femur of the WP (1%, 2%) groups were also higher than t hose of the Cont groups in Exps. 1 and 2. These data indicate that the milk whey protein influence in OVX rats is an increase in bone protei ns such as collagen and enhanced bone-breaking energy.