# Effects of Chicken Protein Hydrolysate as a Protein Source to Partially Replace Chicken Meal on Gut Health, Gut Microbial Structure, and Metabolite Composition in Cats

## TL;DR

This study shows that replacing chicken meal with chicken protein hydrolysate improves gut health and changes gut microbes in cats.

## Contribution

The study is the first to demonstrate the effects of chicken protein hydrolysate on feline gut microbiota and metabolites.

## Key findings

- Replacing chicken meal with chicken protein hydrolysate reduced calprotectin and fecal gas emissions in cats.
- Hydrolysate diets increased beneficial bacteria like Bacteroides and Bifidobacterium while reducing Alloprevotella.
- Metabolomic changes included increased isodeoxycholic acid and enterolactone in hydrolysate-fed cats.

## Abstract

Protein hydrolysates, formed by the enzymatic conversion of proteins into smaller molecular weight, are known to enhance the well-being of mammals and humans. Nevertheless, the influence of protein hydrolysates on feline gut health remains insufficiently explored. The purpose of this research was to investigate the impact of chicken protein hydrolysate as a protein source on the gut microbiota profiles and gut health in cats. The results indicated that partially replacing chicken meat with chicken protein hydrolysate improved the structure of the gut microbiota and metabolite composition and was beneficial to the intestinal health of cats.

Protein hydrolysates positively affect intestinal function in both humans and animals, but their impact on gut health and the gut microbial profile in cats has not been thoroughly investigated. In this study, a total of 30 adult cats were randomly assigned to one of three dietary treatments for a 60-day feeding trial. The three dietary treatments were as follows: (1) basal diet (CON), (2) diet containing 15% powdered chicken protein hydrolysate (HP15%), and (3) diet containing 15% liquid chicken protein hydrolysate (HL15%). Compared to the CON group, the HP15% group had a decreased calprotectin levels and fecal gases emissions (p < 0.05). A higher abundance of Bacteroidota, Veillonellaceae, and Bacteroidaceae, while a lower abundance of Firmicutes was showed in the HL15% group than that in the CON group (p < 0.05). At the genus level, compared with the CON group, an increased abundance of Bacteroides spp. and Bifidobacterium spp. was showed, whereas a reduced abundance of Alloprevotella spp. was presented in the HP15% and HL15% groups (p < 0.05). The metabolomic analysis revealed 1405 distinct metabolites between the HP15% and CON groups (p < 0.05, VIP-pred-OPLS-DA > 1), and the level of cholic acid decreased while the level of isodeoxycholic acid increased in the HP15% group (p < 0.05). The metabolomic analysis revealed 1910 distinct metabolites between the HL15% and CON groups (p < 0.05, VIP-pred-OPLS-DA > 1), and the levels of 4-coumaryl alcohol and enterolactone increased in the HL15% group (p < 0.05). In summary, this study suggested that partially replacing chicken meat with chicken protein hydrolysate in the diet of cats helps regulate the gut microbial community and metabolite profile and improves intestinal health.