Effects Of Dry Powder Of Dendrobium Leaves On Production Performance,intestinal Health And Leg Bone Health Of Laying Hens

With the development of layer breeding industry,more and more attention has been paid to the health of laying hens.The health state of laying hens can ensure the production performance and egg quality.Supplementation of natural and pollution-free plants or plant extracts in the diet of laying hens has also become a hot research topic.Dendrobium officinale has very important pharmacological effects.Its stem is often used as medicine,while the leaf is usually a byproduct.Due to their similar chemical composition,studies on the pharmacological effects of dendrobium officinale leaf are gradually increasing.A large number of studies have shown that Dendrobium officinale leaf has the pharmacological effects of improving immune performance,antibacterial ability,anti-inflammatory ability and protecting digestive system.Most of these studies are conducted in mice,with few studies on domestic animals such as laying hens.This experiment was conducted to investigate the effects of dendrobium officinale leaf dry powder on performance,egg quality,serum biochemical level,immune performance,intestinal health and leg bone health of laying hens.1.Effects of Dendrobium officinale leaf dry powder on performance of laying hensThe purpose of this experiment was to explore the effects of Dendrobium candidum leaves on production performance,egg quality and serum biochemical indexes of laying hens.Two hundred and forty healthy 19-week-old Jinghong No.1 laying hens were randomly divided into three groups: control group,1200mg/kg Dendrobium candidum leaf group and 3600mg/kg Dendrobium candidum leaf group.The results showed that compared with the control group,3600mg/kg Dendrobium leaves could significantly reduce the average daily feed intake and egg breakage rate of laying hens aged 31-34 weeks,and significantly increase the yolk color and serum globulin level of 19-22 weeks old hens.1200mg/kg Dendrobium leaves could significantly reduce the average daily feed intake and egg breakage rate of 31-34 weeks old hens,and significantly increase the yolk color and yolk ratio,Haugh unit and serum total protein levels of 31-34 weeks old hens.The results indicated that the dry powder of Dendrobium leaves did not affect the laying performance of laying hens,but could improve the egg quality.2.Effects of Dendrobium officinale leaf dry powder on immune performance,cecal microflora,short-chain fatty acids and intestinal barrier of laying hensThis experiment was conducted to investigate the effects of dendrobium officinale leaf dry powder supplementation on immune performance,cecal microflora diversity,cecal content shortchain fatty acid content,duodenal intestinal barrier and intestinal inflammation related gene expression of laying hens.Eight laying hens were randomly selected from each group,and cecal contents and duodenal intestinal tissue were collected.The structure of cecal microflora was measured by 16 Sr RNA sequencing.Duodenal RNA was extracted and the m RNA expression levels of intestinal barrier and inflammatory factor related genes were determined.The results showed that spleen index,serum total protein,globulin and Ig G concentrations in the 3600 mg/kg Dendrobium officinale leaf group were significantly higher than those in control group.The relative abundance of Desulfobacterota in 1200 mg/kg and 3600 mg/kg Dendrobium officinale leaf groups was significantly lower than that in the control group.Compared with the control group,the relative abundance of Bacteroidales in 1200 mg/kg and 3600 mg/kg Dendrobium officinale leaf groups was significantly increased,while Desulfovibrio,Mailhella and Alphaproteobacteria were significantly decreased.The m RNA expression levels of Occludin,Cadherin,Claudin-1,Claudin-3,Claudin-5,ZO-1,ZO-2 and ZO-3 genes in the duodenum of3600mg/kg dendrobium officinale leaf group were significantly up-regulated compared with the control group.The m RNA expression levels of Occludin,Claudin-3 and ZO-3 in the duodenum of1200 mg/kg Dendrobium officinale leaf group were significantly up-regulated compared with control group.Moreover,the m RNA expressions of IL-1β,IL-2α,TLR2,IFN-γ,TGF-β3 and TNF-α genes in the duodenum of 1200mg/kg and 3600mg/kg groups were significantly lower than those of the control group.The results indicated that dendrobium officinale leaf dry powder could increase the diversity of cecal microflora,decrease the abundance of sulfur producing bacteria and opportunistic bacteria Alphaproteobacteria,promote intestinal barrier function and reduce intestinal inflammation.3.Effects of Dendrobium officinale leaf powder on leg bone health of laying hensThis experiment was conducted to investigate the effects of Dendrobium officinale leaf dry powder on leg bone health and bone metabolism related gene expression levels of Jinghong no.1laying hens.Eight laying hens were randomly selected from each group.Tibia and femur of the right leg were collected,and bone tissue was collected from the diaphysis of femur of the left leg.Bone morphology,bone density and bone strength of the femur and tibia were measured.The expression levels of bone metabolism and cytokine related genes were determined by extracting diaphysis RNA.The results showed that Dendrobium officinale had no significant effects on bone strength,bone mineral density and bone size of thigh bone(tibia and femur)of laying hens.It can significantly up-regulate the expression levels of osteogenesis related genes including VEGFA,OPG,MMP-9,CD147,RUNX2 and BMP2 as well as osteoclastogenesis related genes CTSK and RANKL.Dendrobium officinale leaves also up-regulated anti-inflammatory cytokines including IL-4,IL-10,TGF-β3 and TGF-β4 that enhance bone formation and proinflammatory cytokines including IL-6 and TNF-α that promoted bone resorption.In conclusion,Dendrobium officinale leaf can promote bone formation and resorption at the same time,enhancing bone metabolism,but have no significant effect on bone density and bone strength of laying hens.To sum up,although the addition of Dendrobium leaf dry powder to the diet of laying hens had no significant effect on the laying performance,it could improve the egg quality and immune performance;reduce the egg breakage rate,the relative abundance of sulfur-producing bacteria and conditional pathogenic bacteria in the intestinal tract and the gene expression of inflammatory factors;increase the relative abundance of beneficial bacteria in the intestine and the expression of m RNA genes related to intestinal barrier function;and promote the bone resorption of leg bone in layers,but had no significant effect on bone mineral density and bone strength of leg bone in laying hens.This study provided a theoretical basis for the application of Dendrobium officinale leaf in intestinal health of livestock and poultry.