The aim of this research was to evaluate, in vitro, the effect of some prebiotic substances and two dietary protein levels on the composition and activity of feline fecal microbiota.

Two in vitro studies were conducted. First, six diets with non-digestible oligosaccharides were studied: Control diet, gluconic acid (GA), carrot fiber (CF), fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), lactitol (LAC) and pectins from citrus fruit (PEC). Substrates were added to feline fecal cultures at 2 g/L for 24-hour incubation. Compared with the control, ammonia had been reduced by GOS after six hours and by GA, LAC and PEC after 24 hours. After 24 hours, all treatments had resulted in a lower pH versus the control. Putrescine concentrations at 24 hours were greater in cultures treated with FOS, GOS and LAC. Compared with the control, total VFA were higher in bottles containing CF, whereas the acetic to propionic acid ratio was reduced by LAC. After 24 hours, Enterobacteriaceae had been reduced by LAC and PEC.

In a second study, LAC and FOS were selected to be tested in the presence of two diets differing in their protein content. There were six treatments: control diet (CTRL Low Protein (LP)), high protein diet (CTRL HP), LP diet + FOS (LP+FOS), HP diet + FOS (HP+FOS), LP diet + LAC (LP+LAC) and HP diet + LAC (HP+LAC). Both FOS and LAC were added to feline fecal cultures at 2 g/L for 24-hour incubation. Ammonia at 24 hours was affected by the protein level. The HP diets resulted in a higher pH and increased concentrations of biogenic amines were found after six and 24 hours of incubation; putrescine at 24 hours showed an increase in cultures treated with FOS. Total VFA were influenced by the protein level. At 24 hours, the HP diets were associated with increased C. perfringens and reduced Lactobacillus spp. and enterococci counts.

The results from the current research show that different prebiotics exert different effects on the composition and activity of feline intestinal microbiota and that high dietary protein levels in a cat's diet can have negative effects on the animal intestinal environment.

Source:  C. Pinna et al., 2014. In vitro effect of dietary protein level and non-digestible oligosaccharides on feline fecal microbiota. J Anim Sci online, November 2014. doi: 10.2527/jas.2013-7459.