Alterations in the Intestinal Microbiome and Metabolic Profile of British Shorthair Kittens Fed with Milk Replacer

Abstract

With the rising popularity of pet cats as companion animals, the survival of newborn kittens is often threatened by factors such as inadequate nursing, maternal behavior and blood incompatibility. These challenges require the use of milk replacers for nurturing. To investigate the effects that feeding kittens with an experimental milk replacer (EMR) have on growth and development, intestinal microbiota, immune response and nutrient metabolism, 12 British shorthair kittens were randomly divided into two groups after nursing for the first week of life. Kittens were fed queen's milk or EMR, whereby kittens fed queen's milk served as the control (CON) group. The findings revealed that the CON group exhibited superoxide dismutase (SOD) activity and total antioxidant capacity (T-AOC) (p < 0.01) on day 7. However, the EMR group had better growth performance during the later stage of the experiment (p < 0.05); the immunocompetence and antioxidant capacity of the EMR group were not significantly different from those of the CON group in the middle and late stages of the experiment, and the mean values of all the indexes were slightly better than those of the control group. Sequencing of the 16S rRNA gene in microbiota demonstrated that EMR increased the colonization of bacterial genera, including Lachnospiraceae, Enterococcus, Rothia and Ligilactobacillus. Compared to the CON group, acetate acid (p < 0.05), propionate acid (p < 0.01) and total SCFAs (p < 0.01) in the EMR group were significantly increased. Moreover, the intake of the EMR resulted in the production of distinct metabolites implicated in the metabolism of lipids and amino acids, among other nutrients, thus invigorating the associated metabolic pathways. These results elucidate the impact of administering a milk replacer on gastrointestinal health and nutrient assimilation in kittens. The study provides insights into the use of milk powder alternatives and sets the stage for future research on the formulation and effectiveness of kitten milk replacers.

Keywords: cat; gut microbiota; metabolic pathways; metabolomics; microbiome; milk replacer.

Figure 1

The effect of experimental milk replacer on the weight gain rate of British shorthair kittens. Data on body weight changes in kittens from 0–7 days, 7–14 days and 14–28 days during the trial period were analyzed. Data are presented as mean ± SEM. * p < 0.05; ns, p > 0.05.

Figure 2

Effects of feeding experimental milk replacer on intestinal microbiome. (A) The diversity of the intestinal microbiome in CON and EMR groups (the bars located to the left of the dashed line correspond to the left y-axis, while the bars on the right of the dashed line correspond to the right y-axis). (B) OTU Venn diagram. (C) Principal coordinate analysis of the intestinal microbiome in CON and EMR groups. (D) Effects of feeding experimental milk replacer on the phylum-level composition. (E) Effects of feeding experimental milk replacer on the genus-level composition (the legend shows the top 10 genera in terms of abundance). (F,G) LDA score plot generated from LEfSe of 16S rRNA gene amplification sequencing data (LDA score > 2, p < 0.05) and Taxonomic cladogram. Green indicates enriched taxa in the CON group. Purple indicates enriched taxa in the EMR group. Each circle’s size is proportional to the taxon’s abundance. Data are presented as mean ± SEM; C, a control group; E, experimental milk replacer feeding group.

Figure 3

Effect of experimental milk replacer on inflammatory substances in the feces of British Shorthair cats on days 7, 14 and 28 of the trial period. (A) Concentrations of calprotectin. (B) Concentrations of Lactoferrin. Data are presented as mean ± SEM. ns, p > 0.05.

Figure 4

Effect of experimental milk replacer on fecal antioxidant capacity in British shorthair kittens on days 7, 14 and 28. (A) Concentrations of superoxide dismutase. (B) Concentrations of malondialdehyde. (C) Total antioxidant capacity. Data are presented as mean ± SEM. * p < 0.05; ** p < 0.01; ns, p > 0.05.

Figure 5

Effects of experimental milk replacer on fecal fermentation metabolites in British shorthair kittens. Data are presented as mean ± SEM. * p < 0.05; ** p < 0.01; ns, p > 0.05.

Figure 6

Effect of experimental milk replacer on fecal metabolites in British shorthair kittens. (A) PLS-DA models of fecal metabolites in CON and EMR groups (PLS-DA models: R2Y = 0.998 and Q2 = 0.907). (B) Volcano plot of differently expressed fecal metabolites. The dashed horizontal line signals statistical significance threshold (p ≤ 0.05). (C) Metabolic pathways influencing factor bubble diagram. (D) Classification of significantly enriched KEGG pathways of differently expressed metabolites (pathways that do not demonstrate relevance to the classification of human disease and drug development). (E) Statistical map of the number of differentially enriched metabolic pathways.