Digestibility and palatability of dog foods containing different moisture levels, and the inclusion of a mould inhibitor

The objective of the present study was to evaluate voluntary intake, first choice, digestibility, and faecal ammonia concentration of adult dogs fed dry extruded foods containing two different moisture levels, and the inclusion or not of propionic acid. Four treatments were compared: low-moisture food (81 g/kg) without propionic acid (LM0P), high-moisture food (102 g/kg) without propionic acid (HM0P), high-moisture food with low inclusion of propionic acid (0.65 g/kg) (HMLP), and high-moisture food with high inclusion of propionic acid (1.3 g/kg) (HMHP). No differences (P>0.05) in diet digestibility, energy metabolizability, or faecal consistency were detected. However, the dogs fed the HMHP diet presented lower faecal ammonia concentration (P=0.003) as compared to the others. Dogs fed the HMLP and HMHP diets presented higher (P<0.001) voluntary intake and first choice as compared to those fed the LM0P diet. It was concluded that the inclusion of 1.3 g/kg propionic acid in the diet did not affect its digestibility; however, it reduced faecal ammonia concentration. The diets containing propionic acid (0.65 or 1.3 g/kg) and high moisture level (102 g/kg) positively influenced food intake and food first choice.