The acceptability and digestibility of mixtures containing selected fats of animal, vegetable and blended sources were studied. Ten fat containing mixtures were fed to Saddlebred horses in cafeteria style palatability trials and ranked according to preference. Preference ranking of the fats from highest to lowest is as follows: corn oil, blend no. 1, cottonseed oil, inedible tallow and fancy bleached tallow. When the most preferred fats from each classification (animal, vegetable and blended) were offered in single mixture palatability trails, no significant difference was observed in consumption. In Digestion Experiment I three fats, corn oil, blend no. 3 and inedible tallow, were added to an alfalfa and grain diet at the 102 level. The apparent digestibility of fatty acids in corn oil when calculated by difference, was higher than an inedible tallow or blend no. 3. The apparent digestibility of energy in corn oil calculated by difference, was 95.4%. However, this value was not different from that of inedible tallow and blend no. 3. The addition and kind of fat did not affect the apparent digestibility of acid detergent fiber or apparent absorption of minerals. Blood serum levels of total fatty acids, calcium, inorganic phosphorus, magnesium and glucose were not affected by the addition of the fats. However, serum cholesterol levels were increased (P <.05) by addition of fat. In Digestion Experiment II, feeding four fats (corn oil, peanut oil, inedible tallow and blend no. 3) at two levels (7.5 and 152%) was studied. When the apparent digestibility of fatty acids in the diet was calculated by difference, the average values were higher for corn oil and peanut oil, but the differences were not significant. The true digestibility of fatty acids showed all fat sources and levels were digested similarly. The apparent digestibility of diet energy was increased by the addition of the fats. The energy of diets containing corn oil had higher (P <.05) digestibilities than those containing inedible tallow or blend no. 3. As in Experiment I, there was no difference in energy digestibility of the added fats when calculated by difference. There was no depression of calcium absorption due to kind or level of added fat. Apparent absorption of phosphorus was not affected by type of level of added fat. Apparent absorption of magnesium was higher (P <.05) for the basal diet and those diets containing blend no. 3. Blood serum levels of total fatty acids, calcium, inorganic phosphorus, magnesium, cholesterol and glucose were not affected by the addition or type of fat. / Ph. D.