## 3 Results
### Fecal Microbiota Analysis  
The fecal samples of the cats were sequenced. Rank abundance curves can reflect the abundance of microbiota community. The data revealed the rarefaction curve, as shown in Figure 2a, which meant the sample size was sufficient to prove the richness of the \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{1}{c}{**Parameter**} & \multicolumn{1}{c}{**Day 0**} & \multicolumn{1}{c}{**Day 28**} \\  & **(Group A)** & **(Group B)** \\ \hline \multirow{2}{*}{Growth} & fat digestibility, \% & 0.88 \(\pm\) 0.07 \({}^{\text{a}}\) & 0.93 \(\pm\) 0.03 \({}^{\text{b}}\) \\  & weight, g & 3.01 \(\pm\) 0.70 & 2.96 \(\pm\) 0.78 \\ \hline \multirow{3}{*}{SCFAs} & acetic acid, mg/mL & 8.59 \(\pm\) 0.50 & 9.73 \(\pm\) 0.85 \\  & propionic acid, mg/mL & 2.70 \(\pm\) 0.58 & 3.72 \(\pm\) 0.95 \\ \cline{1-1}  & butyrate acid, mg/mL & 2.63 \(\pm\) 0.75 \({}^{\text{a}}\) & 5.54 \(\pm\) 0.40 \({}^{\text{b}}\) \\ \cline{1-1}  & isovaleric acid, mg/mL & 0.56 \(\pm\) 0.04 & 0.51 \(\pm\)0.17 \\ \hline \hline \end{tabular} Note: The different superscripts in the table denoted significant difference (\(p<0.05\)), and there was no significance without superscripts (\(p>0.05\)) \(n=5\).  
\end{table} 
Table 1: Effect on growth, fat digestibility and SCFAs in feline feces. \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{**Blood Biochemical Indices**} & \multicolumn{1}{c}{**Day 0**} & \multicolumn{1}{c}{**Day 28**} \\  & **(Group A)** & **(Group B)** \\ \hline TP, g/L & 81.04 \(\pm\) 8.65 & 81.53 \(\pm\) 11.15 \\ ALB, g/L & 31.47 \(\pm\) 3.05 & 29.75 \(\pm\) 2.24 \\ TBIL, umol/L & 3.67 \(\pm\) 0.91 \({}^{\text{a}}\) & 5.44 \(\pm\) 1.91 \({}^{\text{b}}\) \\ GLO, g/L & 49.57 \(\pm\) 9.82 & 51.78 \(\pm\) 11.08 \\ TBA, umol/L & 3.41 \(\pm\) 1.82 & 4.62 \(\pm\) 2.48 \\ AMY, U/L & 1643.14 \(\pm\) 261.06 \({}^{\text{a}}\) & 1991.67 \(\pm\) 247.98 \({}^{\text{b}}\) \\ TG, mmol/L & 0.64 \(\pm\) 0.16 & 0.73 \(\pm\) 0.19 \\ CHOL, mmol/L & 4.11 \(\pm\) 0.74 \({}^{\text{a}}\) & 3.25 \(\pm\) 0.58 \({}^{\text{b}}\) \\ \hline \hline \end{tabular} Note: \(n=5\) TP = the total protein; ALB = albumin; TBIL = total bilirubin; GLO = globulin; TBA = total bile acid; AMY = amylase activity; TG = triglyceride; CHOL = cholesterol. The different superscripts in the table denoted the significance difference (\(p<0.05\)), and there was no significance without superscripts (\(p>0.05\)).  
\end{table} 
Table 2: Alterations in blood biochemical indices in cats. microbiota community. The alpha diversity of the microbial community was measured using Chao1 Indices, Shannon Indices, ACE Indices and Simpson Indices, and there were no significant differences between group A and group B (\(p>0.05\)) (Figure 2c). Beta diversity evaluates differences in the microbiome among samples and was normally combined with dimensional reduction methods, such as principal coordinate analysis (PCoA), to obtain visual representations (Figure 2d). After supplementation of duck bile acid extract, the abundance of Actinobacteria was increased greatly, and the abundance of Firmicutes and Proteobacteria were decreased (\(p>0.05\)) (Figure 3a,b). At the genus level, the abundance of _Bifidobacterium_, _Lactobacillus_ and _Megasphaera_, the core probiotics in the gut, was improved after using the bile acid product (Figure 3c). Differences in microbiota were also determined using LefSe. Significance in species was observed between day 0 (Group A) and day 28 (Group B). The abundance of genus _Bifidobacterium_ spp. on day 28 was higher after using Bas, and the genus _Holdemanella_ was more abundant on day 0 than day 28 (Figure 4) (\(p<0.05\)). Figure 2: BAs alters gut microbiota richness and diversity in cats. (**a**) Rank abundance curves. (**b**) \(\alpha\)-diversity indices dilution curves. (**c**) Chao 1 indices were used to analyze \(\alpha\)-diversity of feline fecal microbiota in group A and B. (**d**) \(\beta\)-diversity of fecal microflora was determined by principal coordinate analysis (PCoA). Figure 4: \(Cont\).