INFLUENCE OF DIETARY FAT ON ENERGY CONSUMPTION AND DIGESTION AND ON NITROGEN UTILIZATION OF WEANLING RATS

Energy digestibility and nitrogen retention were determined with weanling albino rats of the Sprague-Dawley strain fed diets varying from 0 to 30 per cent corn oil and containing 3 ratios of Cal. apparent digestible energy per gm. apparent digestible nitrogen at each fat level. Vitamins, salts and pure linoleic acid were included in the diets at calculated constant levels relative to the apparent digestible energy content. A 7-day metabolism, period followed a 7-day diet acclimatization period. Food consumption varied inversely with the digestible energy content of the diet so that intake of digestible Cal. remained essentially constant and gain in weight of the rats was similar at all fat levels. Nitrogen levels per se did not influence digestible energy consumption but an interaction existed between fat × nitrogen levels in the diet in relation to digestible energy intake. Efficiency of food utilization improved as either fat or nitrogen levels in the diet increased. Energy digestibility was decreased slightly by the addition of fat to a fat-free diet when allowance was made for the influence of non-nutritive cellulose levels in the diets. The addition of fat to the diet resulted in a significant improvement in nitrogen digestibility and gross nitrogen retention.