EFFECT OF ISOENERGETIC SUBSTITUTION OF DIETARY-FAT (BEEF TALLOW) FOR CARBOHYDRATES (WHEAT-STARCH) ON THE CALCIUM-ABSORPTION IN THE DOG

The influence of a high-fat diet on the calcium absorption by growing dogs was determined in a crossover study with five 6-month-old beagles fed two diets with different fat contents. The dogs were fed a pellet ed control diet (11 g fat/100 g diet) and a high-fat diet (33 g fat/10 0g diet) according to the energy requirement for growing dogs. The hig h-fat diet was formulated by isoenergetic replacement of wheat starch by beef tallow. The apparent calcium absorption was determined using c alcium metabolic studies. Studies with orally administered Ca-45 were used to determine the daily amount of true calcium absorption and the intestinal absorption coefficient (alpha). High fat intake coincided w ith higher calcium intake and faecal loss, but neither decreased the a pparent or true calcium absorption, nor influenced alpha. Apparent fat absorption was 97% during both diet regimens. The total faecal excret ion of fatty acids increased in proportion to fat intake, with a signi ficant difference in the excretion of fatty acids after acidification of the faeces for the high-fat diet. Assuming that only calcium soaps were formed, the calcium content involved in the formation of calcium soaps is calculated to be no more than 1.8% of the calcium intake on t he high-fat diet. It was concluded that the formation of calcium soaps is negligible in relation to the calcium intake in this study.