Effects Of Chitosan On Growth Performance In Broiler Chickens And The Underlying Growth-Stimulating Mechanism

Antibiotic and other chemically synthesized drugs were being used excessively, which had brought serious negative effects on human and animal health, ecology and environment protection, and on the development of Animal Husbandry in china, new green feed additives with none of these disadvantages were expected. Nowdays, Chitosan has become focus of study as a kind of excellent feed additive, with the advantages of esculent, antibacterial, hastening immunity function, security and no poisonous, innoxious to environment, none-residue in animal body etc.The experiments were carried out to study the effects of chitosan on growth performance, blood serum indices, utilization of nutriment, growth of gut villi, caecal VFA and intestine pH in broiler chickens, in order to prove the additive efficiency of chitosan and probe into the possible growth-stimulating mechanism of chitosan, moreover, to select the suitable additive dose.252 1-day-old AA male broiler chickens, with similar body weight ,were randomly allotted into six treatments with six replicates in each treatment, with seven broiler chickens in each replicate.The experiments involved six dietary levels of chitosan supplement (control: 0.00%; treat1: 0.02%; treat2: 0.05%; treat3: 0.1%; treat4: 0.3%; treat 5:0.5%).The results showed as follows: 1.The effects of chitosan on growth performance were related to the dose of chitosan added to the diet, at 0.05% level, chitosan gave the best body weight and feed gain ratio (P<0.05),compared with the control group,average body weight raised by 10.29%; but at 0.5% level, chitosan did not promote growth (P>0.05). 2.The results indicated that addition of 0.05% chitosan enhanced nitrogen retention and utilization efficiency compared with the control group (P<0.05), and also raised apparent metabolizable energy retention (P<0.05), while nitrogen utilization efficiency and apparent metabolizable energy retention of 0.5% chitosan were the worst; the metabolism rate of dry matter and apparent metabolizable energy was unaffected obviously. 3.Addition of 0.5% chitosan decreased the metabolism rate of fat in diets (P<0.05),the metabolism rate of calcium and blood serum cholesterol , Triglyceride (P>0.05); compared with control,addition of chitosan all group raised blood serum phosphorus in different degrees. 4.Addition of 0.02%～0.5% chitosan in broiler chicken diets raised caecal acetic acid,butyric acid and total acid content, decreased caecal pH, and improved inner environment of intestine,addition of 0.02%～0.3% chitosan in diets accelerated growth of gut villi,which made gut villi become higher,thinner and density of gut villi become larger. 5.The results showed that, 0.05%～0.3% were the most suitble addition levels of chitosan in broiler chicken diets,and that 0.05% was the most suitble addition level. 6.The results suggested that growth-stimulating mechanism of chitosan were that chitosan promoted growth of gut villi and strengthened absorb function of intestine through improved inner environment of intestine,thus enhanced absorb utilization of nutriment,consequently quickened growth of broiler chickens.