Effects of star anise (Illicium verum Hook. f) and its extractions on carcass traits, relative organ weight, intestinal development, and meat quality of broiler chickens

Star anise (Illicium verum Hook. f) has been used as spice and herbal medicine for many years with lacking researches on evaluating its application for improving relative organ weight, intestinal development, and quality of animal products. The experiment was conducted to investigate the effects of star anise, its essential oil and leavings on carcass traits, relative organ weight, intestinal development, and meat quality of broiler chickens. A total of 384 broilers were randomly assigned to 4 treatments with 8 replicates of 12 birds each. The 4 dietary treatments were basal diet (Control), basal diet supplemented with 5 g/kg star anise (Star anise), basal diet supplemented with 0.22 g/kg essential oil (Essential oil), and basal diet supplemented with 5 g/kg leavings (Leavings). The concentration of main active components in the experimental diets was 0.204 g trans-anethole/kg of diet. All birds were fed a starter diet (0–21 d) and a grower diet (22–42 d). Birds supplemented with star anise and essential oil had a greater (P < 0.05) final body weight (BW) than control birds and those supplemented with leavings. However, the carcass yield, half chamber rate, eviscerated rate, and percentages of breast muscle and thigh muscle in birds were similar (P > 0.05) among all treatments. Birds supplemented with star anise and essential oil had higher (P = 0.010) relative weight of thymus than those in control and leavings groups. Essential oil supplemented groups appeared to contain the highest (P < 0.05) villus height in ileum and villus height/crypt depth ratio in ileum and jejunum among all the groups. Meanwhile, among all the groups, breast muscles of essential oil–supplemented groups appeared to contain the lowest (P = 0.012) boiling loss but highest (P < 0.001) concentration of inosinic acid (inosine 5′-monophosphate, IMP). In conclusion, dietary supplementation of 5 g/kg star anise and 0.22 g/kg essential oil improved BW, relative organ weight, and intestinal development, and 0.22 g/kg essential oil can also increase the concentration of IMP but decrease the boiling loss in breast muscles of broilers; however, 5 g/kg leavings had no effect.