Growth performance and physiological responses of growing japanese quail to methanolic lettuce (Lactuca sativa L.) leaf extract in drinking water.

The current study assessed the impact of lettuce leaf extract (LLE) supplementation in drinking water as a natural substitute for antibiotics on growth performance, antioxidant status, immune response, gut microbiota, and intestinal morphology in growing Japanese quail. A total of 375 nine-day-old Japanese quail chicks were randomly allocated into five experimental groups for the experiment: a negative control group, a group that received colistin, and three groups that received LLE at 1, 2, or 3 mL/L of drinking water. The supplementation continued until the chicks were 39 days old. The methanolic LLE had a lot of phenolics and flavonoids and was a strong antioxidant. In comparison to the control and colistin groups, birds that got 2- and 3-mL LLE had much higher body weight and body weight gain, as well as a better feed conversion ratio (P<0.05). LLE supplementation positively influenced serum biochemical parameters by elevating albumin levels and decreasing urea concentration (P<0.05), while preserving normal liver and kidney function. LLE also made lipid metabolism much better by lowering concentrations of cholesterol, triglycerides, and low-density lipoprotein and rising concentrations of high-density lipoprotein. The antioxidant status was significantly improved (P<0.05), as shown by higher levels of glutathione peroxidase, glutathione-S-transferase, and glutathione and lower levels of malondialdehyde. Higher levels of immunoglobulin G made the immune response better. The total bacterial count in the cecum was significantly decreased, especially at 2 mL LLE, with no negative effects on the histology of the intestines or liver. Furthermore, LLE supplementation increased the surface area of the intestines (P<0.05), which suggests that the gut was working better. Generally, addition 2-3 mL/L of LLE to drinking water enhanced quail growth, metabolic health, antioxidant resistance, immunity, and gut health.