The effect of ageing on nutrient digestibility by cats fed beef tallow-, sunflower oil- or olive oil-enriched diets

Nutrient digestibility and absorption decline with age in several mammalian species. The aim of this study was to compare apparent fat digestibility o f different dietary fats in young and senior cats. Three diets enriched wit h either beef tallow (high in saturated fatty acids), olive oil (high in mo nounsaturated fatty acids) or sunflower oil (high in polyunsaturated fatty acids) were fed to 6 young (3.0+/-0.9y) and 6 senior (11.6+/-1.4y) cats at 300kJ metabolisable energy/kgBW(0.75)/d in a 3*3 Latin square design. Food and faecal samples collected over two consecutive 7d periods were analysed for fat, protein, moisture, ash, gross energy and fatty acid content. Apparent digestibilities of fat and energy were significantly lower (P=0.03 ) in senior cats compared to young cats (fat: 0.922 compared to 0.944; ener gy: 0.848 compared to 0.885, for senior and young cats, respectively) in al l three diets. Senior cats exhibited a lower apparent digestibility for all fatty acid gro ups compared to the younger cats (saturated: 0.932 compared to 0.952; monou nsaturated : 0.964 compared to 0.982; polyunsaturated : 0.980 compared to 0 .987, for senior and young cats, respectively). Saturated fatty acids had t he lowest apparent digestibility in both young and senior cats, and shorter chain fatty acids were digested more easily than the longer chain fatty ac ids. These results suggest that the age-related reduction in apparent fat digest ibility was a general phenomenon affecting all fatty acids, and was not due to one particular fatty acid group.