Comparison of carbohydrate content between grain-containing and grain-free dry cat diets and between reported and calculated carbohydrate values

Abstract

Objectives The aim of this study was to compare the carbohydrate content of grain-containing and grain-free dry cat diets and compare major protein and carbohydrate sources of these diets. Methods This was a cross-sectional study of 77 randomly selected dry cat diets (42 grain-containing, 35 grain-free). Reported carbohydrate values were compared between grain-containing and grain-free cat diets. A subset of 25% of diets from each category (grain-containing and grain-free) was analyzed and nitrogen-free extract was calculated as an estimate of carbohydrate content. These calculated values were compared with reported values from the manufacturer. Animal- and plant-sourced ingredients were also compared between grain-containing and grain-free diets. Results Mean reported carbohydrate content of the grain-free diets (n = 35) was lower than the grain-containing diets (n = 41; 64 ± 16 vs 86 ± 22 g/1000 kcal; P <0.001). Reported carbohydrate values were higher than analyzed nitrogen-free extract (n = 20; 79 ± 30 vs 73 ± 27 g/1000 kcal; P = 0.024). Poultry ( P = 0.009) and soy (P = 0.007) were less common in grain-free diets than in diets containing grain. The alternative carbohydrate sources of chickpeas, lentils, peas, potato, sweet potato and cassava/tapioca were more common ( P <0.05) in grain-free diets than in diets containing grain. Conclusions and relevance This sample of grain-free diets had lower mean reported carbohydrate content than grain-containing diets, but there was considerable overlap between groups and individual diets' carbohydrate/nitrogen-free extract content varied widely.

Figure 1

Box and whisker plot of the carbohydrate content of grain-free and grain-containing dry feline diets. Each box represents the interquartile range (25th–75th percentiles), the horizontal line in each box represents the median value, the whiskers indicate the range of observed values that fall within ± 1.5 times the interquartile range, and circles represent outliers

Figure 2

Box and whisker plot of the carbohydrate content of dry feline diets available in mass market retailers as compared with specialty retailers. Each box represents the interquartile range (25th–75th percentiles), the horizontal line in each box represents the median value, the whiskers indicate the range of observed values that fall within ± 1.5 times the interquartile range, and circles represent outliers