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Dietary fibres may affect cats' health, digestive processes and faecal characteristics(1). Such effects depend on the properties of dietary fibres including their potential fermentability by the intestinal microbiota. The fermentability of dietary fibres can be characterised by in vitro methods that simulate intestinal fermentation. The methodology includes incubation of the fibrous substrate of interest with a faecal inoculum from the target animal species. Various considerations for such in vitro methods have been addressed(2)including the required number of faecal donors, which is described in a companion article for cats using similar laboratory procedures and substrates as in the present study(3). As with any analytical method, it is important that the results obtained from an in vitro fermentation method are repeatable and reproducible. The repeatability is defined as the measure of variation for analyses within the same run, whereas reproducibility is the variation among runs(4). Although these types of precision are routinely evaluated for standard laboratory analyses, few studies have specifically examined these for in vitro fermentation methods. This study aimed to evaluate the repeatability and reproducibility of an in vitro method for characterisation of the fermentability of dietary fibres for cats.
Experimental methods
Substrates
Dietary fibres or fibre sources were selected based on their use in cat foods, contrasting chemical composition and anticipated fermentation characteristics(5-7). Substrates were citrus pectin (CP; rapidly and highly fermentable, HM Rapid, TIC Gums), fructo-oligosaccharide (FOS; rapidly and highly fermentable; Orafti® IPS, BENEO-Orafti), guar gum (GG; rapidly and highly fermentable, 8/22, TIC Gums), molassed sugar beet pulp (SBP; slowly and highly fermentable; Research Diet Services) and wheat middlings (WM; slowly and moderately fermentable; Research Diet Services).
Animals, housing and care
A total of five neutered female European shorthair cats (3 to 5 years old), with a mean body weight of 3·4 (sd 0·4) kg were used during this 4-week study. Cats did not receive any antibiotics for at least 6 months prior to faecal collections. The cats were part of a larger colony where cats are housed in group rooms with inside and outside areas. For the detailed design of the group rooms and the climate and light schedules, see...