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1. A total of 648 one-day-old broiler chicks were randomly allocated into six equal groups to investigate the effect of diet supplemented with fermented Ginkgo biloba leaves (FGBL) at different levels on nutrient utilisation, intestinal digestive function and antioxidant activity. 2. Broilers in the six groups were offered basal diet supplemented with either 0, 1.5, 2.5, 3.5, 4.5 and 5.5 g/kg FGBL during the 42-d experiment, respectively. 3. Birds fed with 3.5 g/kg FGBL diet exhibited increased (P < 0.05) body weight gain, feed intake, apparent total tract retention (ATTR) of ether extract (EE) and relative weight of duodenum. Diets supplemented with FGBL increased (P < 0.05) antioxidant and digestive enzyme activities, and decreased malondialdehyde (MDA) concentrations at different degrees in pancreas and small intestine. The expression of antioxidant related genes was up-regulated (P < 0.05) by the transcription factor Nrf2 in small intestine, especially with supplementation of 3.5 and 4.5 g/kg FGBL in the diet. However, 5.5 g/kg diet significantly decreased (P < 0.05) feed conversion ratio and catalase activity (CAT) in the duodenum. 4. Body weight, relative weight of duodenum, amylase and trypsin activities in ileum, total antioxidant capacity (T-AOC) and CAT in duodenum, and glutathione peroxidase (GSH-PX) in ileum increased linearly and quadratically with FGBL content. Activities of amylase in pancreas, trypsin in jejunum, lipase in ileum, and GSH-PX in duodenum and jejunum increased linearly with FGBL content. Body weight gain, ATTR of EE, activities of trypsin in pancreas and amylase in jejunum, total superoxide dismutase activity in duodenum, T-AOC level and concentrations of MDA in the jejunum and ileum showed a quadratic (P < 0.05) dose response as supplemental FGBL level increased. 5. In conclusion, the addition of FGBL had the potential to improve nutrient utilisation, intestinal digestive function and antioxidant activity of broilers. The optimal dietary supplementation dose for broiler production seemed to be 3.5 to 4.5 g/kg. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate and compare the effects of α-tocopherol acetate (vitamin E (VE)) and microencapsulated VE (MVE) on growth performance, meat quality and antioxidant capacity in broiler chickens. A total of 360 d-old broiler chicks were procured and randomly allocated into three groups with 6 replicates. Each replicate had 20 chickens. Chickens were fed with basal diets (CON group) or experimental diets supplemented with 20 mg/kg VE (VE group) or 20 mg/kg MVE (MVE group) for 42 d. The results showed that the MVE group had higher body weight gain (BWG) than the CON and VE groups, and higher gain/feed ratio (G/F ratio) than the CON group during the period of 22-42 d. During the whole experiment, a higher increase in BWG was found in the MVE group than the CON group. Chickens fed on diets supplemented with the VE or MVE had lower abdominal fat percentage, higher pH and antioxidant enzyme activity than the CON group in the breast meat. There was an increased tendency in the hepatic glutathione peroxidase (GSH-Px) enzyme activity of the VE and MVE groups than the CON group. The hepatic mitochondrial total antioxidant capacity and GSH-Px enzyme activity in the MVE group were higher than the CON group. Hepatic 2,2-dipheny-ʟ-picrylhydrazyl scavenging activity of the MVE group was higher than the CON group. These results suggested that the dietary addition of VE or MVE could improve breast meat quality in broilers. MVE supplementation may improve growth performance, hepatic mitochondrial antioxidant capacity and free radical scavenging capacity in chickens. In addition, dietary supplementation of MVE gave better broiler growth performance than VE.