Abstract
Yeast hydrolysate (YH) is rich in amino acids and other nutrients, and as a nutritional supplement it has been widely used in daily nutritional supplements for livestock. However, the role of YH in domestic pets, especially cats, has not yet been determined. The objective of this research was to study the effects of different concentrations of YH on the healthy cats. All cats were randomly divided into four treatments: the control group (T0, n = 6, without YH), treatment 1 (T1, the low concentration group, 0.8% of YH, n = 6), treatment 2 (T2, the middle concentration group, 1.5% of YH, n = 6), and treatment 3 (T3, the high concentration group, 4% of YH, n = 6), and the blood biochemistry, immune indexes and odorous substances in the feces, and microbiome of cats were determined on day 28. Our results showed that YH could increase the immunoglobulin G (IgG) level in the serum (p < 0.01) and reduce 3-methylindole content in the feces (p < 0.01). The acetic acid in the feces of T2 treatment (1.5%YH) was apparently increased compared to the control treatment (p < 0.05). The blood biochemistry indexes were not affected by the YH. Compared to the control group, there was no significant difference in the abundance at the phylum level. On the genus level, the abundance of g_Ruminocococcaceae and g_Lachnospiraceae, the beneficial bacteria in the gut, were decreased in the treatment T3 compared to treatment T1 (p < 0.05), but there was no significance between T1 and T2, which suggested that a high concentration of YH may be negative for gut health. So, the research showed that 1.5% of YH could be the best concentration for the improvement of immunity and gut health for cats.