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.
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