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

Abstract

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.

Keywords: companion animal; gut health; gut microbial community; metabolite profile; protein hydrolysate.

Figure 1

Impact of various dietary regimens on the calprotectin concentration in the feces of cats on Day 30 and Day 60. (1) CON group: basal diet. (2) HP15% group: diet containing 15% powdered chicken protein hydrolysate. (3) HL15% group: diet containing 15% liquid chicken protein hydrolysate. n = 10. ^a,b Different superscript letters denote a statistically significant difference (p < 0.05).

Figure 2

Effects of different diets on fecal hydrogen sulfide and ammonia contents in cats. (A) The content of fecal hydrogen sulfide on Day 30 and Day 60. (B) The content of fecal ammonia on Day 30 and Day 60. (1) CON group: basal diet. (2) HP15% group: diet containing 15% powdered chicken protein hydrolysate. (3) HL15% group: diet containing 15% liquid chicken protein hydrolysate. n = 10. ^a,b Different superscript letters denote a statistically significant difference (p < 0.05).

Figure 3

Effects of different diets on the fecal microbial diversity in cats on day 60. (A) PCoA at the OTU level. (B) Simpson index. (C) Shannon index. (1) CON group: basal diet. (2) HP15% group: diet containing 15% powdered chicken protein hydrolysate. (3) HL15% group: diet containing 15% liquid chicken protein hydrolysate. n = 10.

Figure 4

Alterations in the composition of fecal microbiota in cats subjected to various dietary regimens on day 60. (A) Relative abundance of fecal microbiota at the phylum level. (B) The abundance of Bacteroidota. (C) The abundance of Firmicutes. (D) The abundance of fecal microbiota at the family level. (E) The abundance of Veillonellaceae. (F) The abundance of Bacteroidaceae. (1) CON group: basal diet. (2) HP15% group: diet containing 15% powdered chicken protein hydrolysate. (3) HL15% group: diet containing 15% liquid chicken protein hydrolysate. n = 10. ^a,b Different superscript letters denote a statistically significant difference (p < 0.05).

Figure 5

The abundance of fecal microbiota on genus level on day 60. (1) CON group: basal diet. (2) HP15% group: diet containing 15% powdered chicken protein hydrolysate. (3) HL15% group: diet containing 15% liquid chicken protein hydrolysate. n = 10.

Figure 6

Changes in the metabolites of feces in cats exposed to the different dietary treatments on Day 60. (A) Volcano plots presenting differential metabolites in comparisons of the CON group with the HP15% group, the CON group with the HL15% group, and the HP15% group with the HL15% group (VIP-pred-OPLS-DA > 1, p < 0.05). (B) Scatter plot of PLS-DA results for different metabolites in the CON, HP15%, and HL15% groups in both positive and negative ion modes. (C) The assessment of differential metabolites across the three groups was augmented by VIP scoring and a hierarchical clustering heatmap. (1) CON group: basal diet. (2) HP15% group: diet containing 15% powdered chicken protein hydrolysate. (3) HL15% group: diet containing 15% liquid chicken protein hydrolysate. n = 10.

Figure 7

Analysis of KEGG topology regarding differential metabolites on day 60. (A) The CON group vs. the HP15% group; (B) the CON group vs. the HL15% group; and (C) the HP15% group vs. the HL15% group. (1) CON group: basal diet. (2) HP15% group: diet containing 15% powdered chicken protein hydrolysate. (3) HL15% group: diet containing 15% liquid chicken protein hydrolysate. n = 10.

Figure 8

Correlation analysis between the genus-level gut microbiota and differential metabolites on day 60. * p < 0.05; ** p < 0.01; *** p < 0.001. (1) CON group: basal diet. (2) HP15% group: diet containing 15% powdered chicken protein hydrolysate. (3) HL15% group: diet containing 15% liquid chicken protein hydrolysate. n = 10.