Effects of dietary phytoncides extracted from Korean pine (Pinus koraiensis) cone on performance, egg quality, gut microflora, and immune response in laying hens.

Abstract

This study was conducted to evaluate the effects of dietary phytoncides extracted from discarded Korean pine cones (Pinus koraiensis) on the performance, egg quality, immune response and gut microflora in laying hens. A total of 400 Hy-Line brown laying hens (50-week old) were allotted into four dietary treatments including a control diet or a diet supplemented with phytoncides at 0.002%, 0.004% and 0.008%. During the 6weeks of experimental feeding, 0.008% of dietary phytoncides improved egg production, feed conversion ratio (p<0.05), but not feed intake, egg weight or feed efficiency. Although dietary phytoncides had no effect on egg quality, decreases in Haugh units depending on storage periods were improved by 0.008% of dietary phytoncides (p<0.05). To investigate the roles of dietary phytoncides on the alteration of the immune response during inflammation, lipopolysaccharide (LPS) or saline was intraperitoneally injected into 10 hens per diet group on the end date of the experimental feeding period. Serum immunoglobulins and splenic cytokine expression at mRNA levels were then measured at 4hr postinjection. Although the levels of IgA were decreased by LPS injection in all dietary groups, dietary phytoncides at 0.008% showed a higher level of IgA by LPS (p<0.05). Interestingly, although LPS injection resulted in an enhanced expression of proinflammatory cytokines such as IL-1β and IL-6, dietary phytoncides at 0.008% showed less increased levels of them (p<0.05). Gut microflora was examined from 10 hens per diet group at the end of the experimental period. While the number of Lactobacillus spp. was increased (p<0.05), Escherichia coli counts in the cecal contents were decreased by 0.008% of dietary phytoncides. Taken together, these results demonstrate that dietary supplementation of 0.008% phytoncides improved the egg production, immune responses during inflammation and gut microflora in laying hens.