The effects of dietary supplementation of microencapsulated Enterococcus faecalis and the extract of Camellia oleifera seed on growth performance, immune functions, and serum biochemical parameters in broiler chickens

摘要

This experiment was conducted to investigate the effects of microencapsulted Enterococcus faecalis (MEF) and the extract of Camellia oleifera seed (ECOS) on growth performance, immune functions, and serum biochemical parameters in broiler chickens. A total of 240 1-d-old male broilers were randomly allotted into 6 treatments with 8 replicates/treatment and 5 broilers in each cage. The dietary treatments included 1) a basal diet without antibiotic (group A), 2) the basal diet + 1 g MEF/kg diet (1 x 10(10) cfu/g MEF; group B), 3) the basal diet + 300 mg ECOS/kg diet (group C), 4) the basal diet + 300 mg ECOS/kg diet + 1 g MEF/kg diet (group D), 5) the basal diet + 500 mg ECOS/kg diet (group E), and 6) the basal diet + 500 mg ECOS/kg diet + 1 g MEF/kg diet (group F). The feeding experiment included 2 phases: the starter phase from Day 1 through 21 and the grower phase from Day 22 through 42. The results showed that a diet supplemented with MEF and ECOS had no significant effect on ADG, ADFI, feed conversion ratio, and average BW during the whole experimental period (P > 0.05), but group F showed an improving trend in growth performance. Serum IL-2, IgA, and IgG levels and spleen index were significantly affected by dietary treatment (P 0.05). Serum IgA and IgG levels and spleen index in group F were significantly higher than in the group A (P 0.05), and the IL-2 level was significantly decreased (P 0.05) on Days 21 and 42. Compared with the group A, diets supplemented with MEF and ECOS can significantly decrease total cholesterol, low-density lipoprotein cholesterol, triglycerides, and blood urea nitrogen levels (P 0.05) and increase the high-density lipoprotein cholesterol level on Days 21 and 42. Concentrations of serum biochemical parameters were significantly increased in group F (P 0.05). In summary, the results indicated that dietary supplementation of MEF and/or ECOS had no significant effect on growth performance but significantly increased spleen index and the levels of serum IgA and IgG and improved serum lipid metabolism. The 1 g MEF/kg diet (1 x 107 cfu/g diet) plus 500 mg ECOS/kg diet was the optimum supplemental dose in this experiment.