Comparison of the guaranteed analysis with the measured nutrient composition of commercial pet foods

Abstract

Objective-To compare guaranteed and measured concentrations of nutrients in commercial pet foods. Design-Cross-sectional study. Sample Population-Annual inspection reports of pet food analyses from 5 states. Procedures-Guaranteed and measured concentrations of crude protein (CP), crude fat (CF), crude fiber (CFb), moisture, and ash in pet foods were compared. The concentration difference for each nutrient was compared among types of food, target species, target life stages, manufacturers, and laboratories. Results-The guaranteed and measured concentrations of nutrients were significantly different. For all foods, mean concentration differences were as follows: CP 1.5%; CF, 1.0%; CFb, -0.7%; moisture, -4.0%; and ash, -0.5%. Crude protein difference for treats was significantly larger than differences for dry and canned foods, Crude fat difference for dry foods was significantly less than differences for canned foods and treats. Crude fiber and moisture differences for canned foods were significantly less than the corresponding differences for dry foods and treats. Only CFb differences differed among target species, life stages, manufacturers, or laboratories. Conclusions and Clinical Relevance-Addition of 1.5% and 1% to the guaranteed minimums for CP and CF, respectively; subtraction of 0.7%, 4%, and 0.5% from the guaranteed maximums for CFb, moisture, and ash, respectively; and addition of 0.23 kcal/g to the asfed metabolizable energy value calculated by use of modified Atwater factors from guaranteed analyses provides a more accurate estimate of the nutrient and metabolizable energy content of commercial pet foods. Nevertheless, the actual composition of a food should be determined whenever possible. (J Am Vet Med Assoc 2009;234:347-351)