| y-aminobutyric acid (GABA), an important inhibitory neurotransmitter in the animal central nervous system, can improve animal growth performance by controlling the brain feeding centers and stimulating growth hormone secretion and anti-stress. Preliminary study on toxicology and growth enhancing effect of feed-grade GABA was conducted to provide theoretical basis for the safe and rational use of GABA in animal husbandry.Experiment I:Common toxicity of y-aminobutyric acid in miceThe acute toxicity and subacute toxicity of GABA in ICR mice was evaluated in this paper. The results showed that the oral LD50value of GABA in mice was more than10mg·kg-1, the intraperitoneal LD50value was8.78g·kg-1and95%confidence interval was7.84-9.84g·kg-1. GABA didn’t produce significant effects on behavior, body weight gain, organ coefficient, blood routine and serum biochemistry index of mice under500mg·kg-1in subacute toxicity test. GABA belongs to the nontoxic substances and has good safty in clinical application.Experiment II:Genetic toxicity of y-aminobutyric acid in miceThe genetic toxicity of GABA was investigated by sperm deformity test and micronucleus test in vivo. Based on the results of oral LD50test, ICR mice were given different oral doses of the GABA to obersve the sperm deformity rate and micronucleus rate of polychromatic erythrocytes (PCE) in bone marrow under high (1/2LD50), mid (1/4LD50), low (1/8LD50) doses. The results of sperm deformity test and micronucleus test in mice were negative. Significant genetic toxicity of GABA in mice was not found in this experiment.Experiment Ⅲ:Reproductive toxicity in sensitive period to teratogenic agent of y-aminobutyric acid in ratsTeratogenic toxicity of GABA in rats during the period of organ formation was studied in this paper. Mate SD rats were randomly divided into five groups with18rats in each group, three dosage groups (62.5,250and1000mg·kg-1), one negative and one positive control group. GABA and physiological saline was given by gavage to the treated groups and the negative control group for ten days during the period of organ formation (the6th to 15th day of gestation), respectively. Rats in the positive control group were administered intraperitoneal cyclophosphamide on the11th to13th day of gestation at a daily dose of7mg·kg-1. The rats were sacrificed to examine fetuses on the20th day. The results showed that GAB A didn’t produce significant effects on health, behavior, weight gain and reproductive parameters of pregnant rats and fetal growth, and didn’t induce the teratogenic effect on appearance, bones and bowels of fetuses. GABA has no parent toxicity, embryotoxicity and teratogenic toxicity when used under1000mg·kg-1.Experimeent Ⅳ:Effects of y-aminobutyric acid on growth performance of Suqin yellow chickensA single factor design was conducted to study the effects of y-aminobutyric acid on growth performance of Suqin yellow chickens. Seven hundred and twenty1-day-old healthy and sexing Suqin yellow chickens were randomly divided into six groups with4replicates and each replicate contained30chickens (15males and15femals). Group I was set as control group and fed with basal diet, group Ⅱ,Ⅲ,Ⅳ,Ⅴ, and Ⅵ were fed with basal diet added with GABA at dosage of10,25,50,75and100mg·kg-1, respectively. The experiment lasted for49days. The results showed that the diet added with GABA improved average daily feed intake (ADFI), average daily gain (ADG) and feed/gain (F/G) of chickens in different degree, of which the effect of the diet added with25and50mg·kg-1GABA on growth performance reached a significant level (P<0.05). It was indicated that GABA could improve the growth performance of Suqin yellow chickens, and the best added dosage was25～50mg·kg-1. |
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