Effects of dietary supplementation of microencapsulated Enterococcus fecalis and the extract of Camellia oleifera seed on laying performance, egg quality, serum biochemical parameters, and cecal microflora diversity in laying hens

The aim of this study was to investigate the effects of microencapsulted Enterococcus faecalis (MEF) and the extract of Camellia oleifera seed (ECOS) on laying performance, serum biochemical parameters, and cecal microflora diversity in laying hens. A total of 180 Hy-Line Brown laying hens, 26-wk-old, were randomly allocated to 6 treatments with 10 replicates and 3 hens per replicate. Dietary treatments were as follows: (A) control group, basal diet; (B) basal diet + 100 mg MEF/kg diet (1 × 1010 cfu/g MEF); (C) basal diet + 300 mg ECOS/kg diet; (D) basal diet + 100 mg MEF/kg diet + 300 mg ECOS/kg diet; (E) basal diet + 500 mg ECOS/kg diet; (F) basal diet + 100 mg MEF/kg diet + 500 mg ECOS/kg diet. The results showed that diets supplemented with MEF and ECOS had no significant effects on laying rate, average egg size, average daily feed intake, feed conversion ratio, eggshell thickness, albumen height, and yolk color (P > 0.05), but had significant effects on egg shape index, eggshell strength, and Haugh unit (P < 0.05) during whole feeding phases. Compared to the control group, the serum IgA and IgG levels of birds in Group F significantly increased (P < 0.05). The serum total cholesterol, low-density lipoprotein cholesterol, total triglyceride, and blood urea nitrogen levels of birds in Group D and Group F significantly reduced (P < 0.05), and the high-density lipoprotein cholesterol level of birds in Group D and Group F significantly increased (P < 0.05). At the phylum level, Firmicutes decreased (P < 0.05) and Bacteroidetes increased (P < 0.05) in the birds of Group D. Ruminococcus and Bacteroides were significantly affected by dietary treatments (P < 0.05), and Bacteroides in the birds of Group D significantly increased at the genus level. Therefore, diet supplemented with MEF and ECOS can significantly improve serum biochemical parameters and increase cecal microflora diversity.