The Influence of Different Protein, Fat and Mineral Levels on the Digestibility of Fat and Fatty Acids Measured at the Terminal Ileum and in Faeces of Growing Pigs

Abstract

Abstract The influence of dietary protein, fat and mineral levels on crude fat and fatty acid digestibility was investigated in growing pigs. The experiment was a factorial design with two levels of protein (normal and high), two levels of dietary fat (3 and 15% of DM) and three levels of minerals (50, 100 and 150% of Danish Standard). Four litters, each of six female pigs, were used in the experiment. Increasing the dietary protein content resulted in a moderate but significant increase in the ileal digestibility of fatty acids. The increase was most pronounced for the saturated fatty acids. Addition of animal fat to the basal diet caused a substantial increase in ileal digestibility of all fatty acids except stearic acid (18:0). A variation in the dietary mineral content of ±50% of the Danish Standard had no significant influence on ileal digestibility of crude fat and fatty acids. Apparently, microbial hydrogenation occurred in the hind-gut, but the increase in stearic acid (18:0) excretion could not be explained solely by biohydrogenation of unsaturated fatty acids. The interactions between dietary protein and fat on the increase of faecal 18:0 showed that the dietary composition had a very complex effect on the microbial activity in the hind-gut. Consequently, determination of fatty acid digestibility should be performed at the terminal ileum, whereas crude fat (Stoldt) digestibility can be carried out on faecal material.