Synergistic Effects of Sage and Thyme Leaves as Phytogenic Feed Additives on Broiler Growth Performance and Health

This study examined the effects of dietary sage and thyme leaves, fed individually or in combination, on broiler growth performance, carcass characteristics, and hematological and biochemical profiles. A total of 480 one-day-old Hubbard broiler chicks were randomly allocated to four dietary treatments: a basal diet (D1), a basal diet with 0.5% sage (D2), 0.5% thyme (D3), or a combination of 0.25% sage and 0.25% thyme (D4). Birds received the diets for six weeks. The combined treatment (D4) produced the greatest improvements in live body weight and body weight gain (P < 0.01), along with reduced feed intake from the second week onward and better feed conversion ratio during the first and sixth weeks. Carcass yield and most organ relative weights increased in all supplemented groups compared with the control. Thyme supplementation (D3) yielded the highest packed cell volume (PCV), hemoglobin concentration, and red blood cell (RBC) count, whereas sage (D2) increased heterophil numbers, total protein, and globulin concentrations. Birds fed the combined diet (D4) showed the highest white blood cell (WBC) and lymphocyte counts. Chicks on the basal diet (D1) exhibited the highest hemagglutination inhibition (HI) titer, heterophil-to-lymphocyte (H/L) ratio, albumin, uric acid, creatinine, triglycerides, cholesterol, aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Overall, adding sage and thyme to broiler diets can significantly enhance broiler growth performance, carcass traits, and physiological status, and enhanced economic efficiency.