Lactobacilli have played an important role in the gut health of pets. The aim of this research was to study the effects of isolated Lactobacilli (named L11) on the immune, nutrient metabolism, and gut health of cats. Twelve healthy adult cats were randomly assigned into two groups, the control group (CONTROL, n = 6, without any probiotics product) and the treatment group (probiotics, n = 6, L11 10⁹ CFU/kg feed), while using the same dry diet. On day 28, blood and fecal samples were collected, and the blood biochemical indices, fecal microbiota, short-chain fatty acids (SCFAs), immunological parameters, and odorous substances were separately tested. The triglyceride of the blood was decreased after using L11 (p < 0.05), which could probably alleviate the occurrence of cat obesity to some extent. The sIgA of the feces was increased by 30.1% (p < 0.05), which could enhance the cat’s immunity. The abundance of Bifidobacteria was increased after using L11 (p < 0.05), and the indole and 3-methylindole of the feces were both reduced compared with the control group; 3-methylindole was especially reduced by 67.3% (p < 0.05), which showed that L11 could also improve the intestinal state of cats. Therefore, this research shows that L11 could be a good choice to improve the gut health and immune functions of cats, and it is probably related to the lipid mechanism of cats.

Bile acids (BAs) have been widely used on livestock in recent years and could be a good feed additive to improve the performances of animals. But the effects of bile acid on cats have not been studied. The purpose of this research was to investigate the effects of the bile acid from ducks on cats. Five healthy cats, which were two years old, were studied with a dose of the bile acid product being 50 mg/kg body weight per day. On day 0 (group A) and day 28 (group B), the fecal flora, volatile fatty acids, fat digestibility, and blood biochemical Indices of cats were studied and tested. The results showed that BAs could probably modulate the fat metabolism and gut microflora of cats and could improve the digestibility of different nutritional ingredients. The cholesterol of blood was greatly decreased and the cholesterol and activity of amylase were improved by 20.9% (p < 0.05) and 21.1% (p < 0.05), respectively. Fat digestibility was improved by 5.68% (p < 0.05) and the body weight on day 28 was decreased without significance (p > 0.05). The abundance of the Bifidobacterium on day 28 was greatly increased (p < 0.05) after using BAs product. The research showed that duck BAs could modulate fat metabolism and increase probiotics of the gut in cats and could probably be a good feed additive to reduce weight and improve gut health for cats in the future.