Digestibility of Different Fats and Fatty Acids in the Blue Fox (Alopex lagopus)

Abstract

Abstract The influence of the level and type of fat on the digestibility of fat and different fatty acids in the blue fox was studied (experiment A). The possible synergistic effect of saturated and polyunsaturated fatty acids was also clarified (experiment B). The fats employed in experiment A were beef tallow, capelin oil and rapeseed oil and in experiment B beef tallow and soybean oil. Digestibilities were determined by the AIA-indicator method, 0.5% silicate (Celite 545) in feed served as an indicator. The animals in experiment A were adult breeding animals, two males and 2–6 females per group. In experiment B 5-month-old male-female pairs were used, 5 pairs per group. The apparent digestibilities of beef tallow, capelin oil and rapeseed oil on a 15% level of supplemental fat were 88, 96 and 95%, respectively. The corresponding values on a 25% level were 87, 97 and 96%. The digestibilities of beef tallow, soybean oil and their mixture (50:50) on a 20% level of supplemental fat were 93, 96 and 95%, respectively. In experiment A the increase in fat level had no influence on the digestibilities of fat or any other nutrients although it significantly increased metabolizable energy (ME) and its percentage of the gross energy (GE) of the diet. Fat type influenced the digestibility of fat and the utilization of GE. There was also a levelxtype interaction in the ME of the diet. An over 10% increase in tallow level, the proportion of ME derived from fat increasing from 37 to 50%, caused no change in the digestibility of saturated fatty acids or total fat. Although tallow is a very saturated fat source it is fairly efficiently digested in the blue fox. In experiment B a compensatory increase in the digestibility of protein and carbohydrates could be seen in the tallow containing groups compared to the soybean oil group. No synergistic effect between tallow and soybean oil could be found.