Effects of officinal magnolia bark extract supplementation on laying performance, egg quality, antioxidant function and intestinal microorganisms of laying hens in late laying period

To investigate the effects of officinal magnolia bark extract supplementation on laying performance, egg quality, antioxidant function and intestinal microorganisms of laying hens in late laying period, 400 healthy 65-week-old Hyline brown commercial laying hens were randomly divided into four groups with four replicates per group and 25 laying hens per replicate. Laying hens in the control group were fed only a basal diet, while those in the low, medium and high dose groups were fed the basal diet supplemented with 250,500,750 mg/kg officinal magnolia bark extract, respectively. The pre-trial period lasted for three days and the experimental period lasted for 42 days. After the test, the production performance indexes were measured, and the egg quality, serum antioxidant and intestinal microbial indexes were detected. The results showed that compared with control group, the laying rate and average qualified egg weight in the medium dose and high dose groups were significantly increased（P＜0.05）, and the feed to egg ratio was significantly decreased（P＜0.05）; the Haugh unit and eggshell strength in the low, medium and high dose groups were significantly increased（P＜0.05）; the activities of glutathione peroxidase（GSH-Px） and total superoxide dismutase（T-SOD） in the medium and high dose groups were significantly increased（P＜0.05）, and the contentration of malondialdehyde（MDA） was significantly decreased（P＜0.05）; the number of Escherichia coli and Salmonella in the intestinal tract of laying hens in all experimental groups were significantly decreased（P＜0.05）, and the number of lactic acid bacteria was significantly increased（P＜0.05）. These results indicated that officinal magnolia bark extract could improve laying performance, egg quality, antioxidant function and regulate the structure of intestinal flora. The recommended dietary supplement was 500 mg/kg.