Effect of mineral mixture in diet on protein intake regulation in the weanling rat

Weanling rats fed a choice of two diets varying only in protein concentration (10 and 60% casein) select a lower proportion of dietary energy as protein when the dietary minerals are supplied by a mineral mixture high in Na, K, and Cl but low in P and Cu (Hi Cl) than when the diets contain the Bernhart-Tomarelli (BT) mineral mixture. The addition of Na and/or K as acetate salts to the BT mineral mixture, to levels in the Hi Cl mixture, had no effect on regulation of protein intake. However, the addition of Na and/or K as chloride salts to the BT mineral mixture resulted in the rats selecting a protein concentration equivalent to the Hi Cl fed group. Weight gains and energy consumption were similar for all groups. It was therefore concluded that dietary chloride affects protein feeding behavior.