Daily food intake and digestibility in rats

The present work with growing rats was undertaken to study the effect of daily food intake (DFI) on true protein digestibility (TD), and apparent digestibility of dry matter (DM), energy (DE), starch, soluble dietary fibre (SDF) and insoluble dietary fibre (IDF). The design involved two different dietary combinations, barley + rapeseed meal (diet 1) and oats + wheat bran (diet 2). A slight but significantly negative relationship was seen between DFI and TD on diet 1 while no such relationship was found on diet 2. Although significant, DFI influenced DM digestibility of both diets only slightly. A similar situation could also be seen for the effect of DFI on DE. The digestibility of starch was significantly affected by DFI on both diets even though the lowest values were as high as 0.994. SDF digestibility (fermentability) was not influenced by DFI when the rats were given diet 1, while there was a significant negative effect of DFI on digestibility of SDF when diet 2 was given. The digestibility (fermentability) of IDF was not affected by DFI on either of the two diets. The results confirm the existence of a weak negative relationship between DFI and digestibility of a range of nutrients although the effect seems to be only marginal and of no importance under practical feeding conditions.