Regression-derived optimal milk thistle in growing quail's diet

A study was conducted to evaluate the nutritional benefits of milk thistle (Silybum marianum) in quail nutrition as an additive containing antioxidant compounds such as silymarin. A total of 300, 14-d old Japanese quail chicks were randomly allotted to 5 treatments with 6 replicates and 10 birds each. The experimental diets, including a basal diet and 4 diets containing 10, 20, 30, and 40 g/kg milk thistle, were used from d 14 to 35 and spline and segmented models were applied to fit data. The optimized values of dietary milk thistle (breakpoints) for optimum amounts of serum albumin (ALB), total protein (TP), glucose (Glu), magnesium (Mg), calcium (Ca), phosphorus (P), iron (Fe), and water holding capacity (WHC) in meat samples, as predicted by the regression models, were 24.14, 20.00, 20.00, 24.50, 20.00, 10.43, 23.75, and 25.85 g/kg of diet, respectively, based on maximum R2 and minimum Sy.x. While the breakpoints for minimum cooking loss, drip loss, malondialdehyde after 10 and 30 d (MDA10 and MDA30), triglyceride (TG), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), cholesterol (CHOL), uric acid (UA), and creatinine (CRT) were 27.00, 15.82, 15.78, 33.09, 27.39, 17.99, 20.00, 20.00, 20.90, and 32.57 g/kg of diet, respectively. The use of spline models revealed an objective estimate of the optimal amounts of milk thistle for optimizing physiological responses in growing quails. The present analysis showed that higher dietary levels of milk thistle were needed for optimizing meat quality compared to other physiological responses.