Effects Of Biotin On The Physiological And Biochemical Characteristics And Immune Responses In Broilers And Its Mechanism

Seven experiments were conducted to investigate systematically the effects of biotin on growth performance, serum physiological and biochemical characteristics, liver pyruvate carboxylase activity, tissue fatty acids deposition and immune responses in broilers, and explore further the immune mechanism by molecular biology technique.Experiment 1: The experiment was carried out to study the effects of different biotin addition levels in corn-soybean meal diet on growth performance and liver pyruvate carboxylase activity in broilers, which aimed to explore the appropriate addition level of biotin. 960 AA broilers of 1 day were allocated into 6 treatments, 10 replicates per treatment, 16 broilers per replicate. The basal diet was corn-soybean meal diet. Biotin was added in the basal diet at 0.1 mg/kg, 0.2 mg/kg, 0.3 mg/kg, 0.4 mg/kg and 0.5 mg/kg. There were 6 diets including the control of basal diet. The results showed as follows. Addition of biotin in corn-soybean meal diet affected average daily gain (ADG), average daily feed intake (ADFI) and feed conversion efficiency (P>0.05), and increased liver pyruvate carboxylase activity. The liver pyruvate carboxylase activity of 0.3 mg/kg, 0.4 mg/kg and 0.5 mg/kg treatments were higher significantly than that of the control (P<0.05), and there were no significant difference among the biotin addition treatments (P>0.05). The appropriate addition level of biotin was 0.3 mg/kg in corn-soybean meal diet based on growth performance and liver pyruvate carboxylase activity.Experiment 2: The experiment was conducted to evaluate the effects of different biotin addition levels in corn-soybean meal diet on serum physiological and biochemical characteristics and tissue fatty acids deposition in broilers. The results showed as follows. 180 AA broilers of 1 day were allocated into 6 treatments, 30 broilers per treatment. The basal diet was corn-soybean meal diet. Biotin was added in the basal diet at 0.1 mg/kg, 0.2 mg/kg, 0.3 mg/kg, 0.4 mg/kg and 0.5 mg/kg. There were 6 diets including the control of basal diet. (1) Supplementation of biotin affected serum physiological and biochemical characteristics, which decreased serum ALT and AST activities (P>0.05), and increased serum total protein and globin content (P>0.05). With addition of biotin, serum calcium, phosphorus and glucose content and ALK activity showed a tendency to decrease (P>0.05), but serum cholesterol, phosphorus lipid, triglyceride, HDL and LDL content showed a tendency to increase (P>0.05). 1 nclusion of biotin reduced serum glucagons content (P>0.05), and increased T3 T4, insulin and growth hormone content (P>0.05). (2) Biotin addition enhanced tissue fatty acids deposition in broilers. In liver tissue, total fatty acids (TFA), saturated fatty acids (SFA), C16:0, C18:l and C24:0 content were enhanced significantly by addition of biotin (P<0.05). In muscle tissue, supplementation of biotin resulted in a tendency to increase in TFA and SFA (P>0.05), and a significant increase in C20:0, C20:2 and C20:4n-6 content, and C20:4n-6/C18:2n-6 value (P<0.05), and promoted transformation from C18:2n-6 to C20:4n-6.Experiment 3: The experiment aimed to explore the effect of biotin on intestinal micropopulations.60 AA female broilers of 1 day were allocated into 3 treatments, 20 broilers per treatment. The basal diet was corn-soybean meal diet. Biotin was added in the basal diet at 0.2 mg/kg and 0.4 mg/kg. There were 3 diets including the control of basal diet. The results showed as follows. Biotin addition changed intestinal micropopulations and promoted the propagation of Lactobacillus and Bifidobacteria. (1) Lactobacillus amount of the ileum was elevated significantly by addition of biotin (P<0.05). Inclusion of biotin produced a tendency to increase in total aerobic bacteria, E. Colibacillus and bifidobacteria amount (P>0.05), and a tendency to decrease in total anaerobic bacteria amount in ileum (P>0.05). (2) Inclusion of biotin leaded to a marked decrease in E.Colibacillus amount (P<0.05), and a tendency to increase i...