Addition of Protease Enzyme to Dog and Cat Feed and Its Influence on the Digestibility Coefficient, Immune Response, and Metabolic Biomarkers

Abstract

Promoting better protein digestibility through exogenous enzymes in the diet is essential in the nutrition of companion animals, mainly for better performance and maintenance of the animals’ physiological and metabolic systems, promoting health and adequate growth. In addition, it reduces the cost of the diet by possibly reducing protein in the diet, which is the main and most expensive ingredient for dogs and cats. The objective of this study was to verify whether the addition of protease to dog and cat food can improve the protein digestibility of the food, thus facilitating greater absorption of amino acids and influencing metabolic biomarkers and immune response. To this end, two experiments were carried out to evaluate the protease from the fermentation of Aspergillus niger and Bacillus subtilis . Experiment 1 was carried out with ten male, non-castrated beagles divided into two groups of five animals: the control group (without enzyme) and the test group (with 250 g of protease/ton). The animals underwent two 45-day experimental periods, and in the second period, after a 15-day interval, the dogs in the control group became part of the treatment group (crossover model). Adding this enzyme to the dogs’ diet had no adverse effects on the animals’ health besides improving the digestibility of dry matter and crude protein consumed by the dogs. Experiment 2 was carried out with sixteen female cats of no defined breed, non-castrated, divided into four groups with four animals per group, namely: Treatment A (without enzyme), Treatment B (with protease at a dose of 100 g/ton), Treatment C (with protease at a dose of 200 g/ton) and Treatment D (with protease at a dose of 400 g/ton). The cats underwent two 30-day experimental periods, and in the second period, after a 15-day interval, the animals switched between treatments (crossover model) to increase the power of the statistical test. The enzyme consumption did not affect the felines’ metabolism and health but improved the digestibility of crude protein at doses of 200 and 400 g/ton. The results allow us to conclude that the protease used in this study can improve the digestibility of crude protein for dogs and cats.