| An experiment was conducted to study the effects of iodine content in diets on the performance,blood biochemical indexes and the accumulation in the muscle of Saibei Rabbit. A total of eighty-four 50-day-old Saibei Rabbit were selected and divided into seven groups according to the principle of sex equity. One group was control, the others were experimental groups. The rabbits in the control was fed the basic diet in which iodine content was 0.125mg/kg,and the rabbits in the experimental groups were fed the basic diet supplemented with 0.2, 0.4, 0.6, 0.8, 1.0, 1.4mg/kg iodine respectively. After 20d, 40d and 60d, body weight, body length and chest girth of rabbits were measured. After 60d, all rabbits were slaughtered, and the skin areas, the carcass weight, the dressing percentage, the blood biochemical indexes, the content of iodine in the muscle and liver, the feed conversion efficiency and the survival rate were detected and analyzed. The results showed as follows:(1)Iodine supplementation could significantly increase the average daily gain, body length and skin area of Saibei Rabbit. During the whole experiment period, daily gain of the experimental groups was higher than that of the control, and the body length and skin areas were the same. When adding 0.8 mg/kg iodine into diets in which practical content of iodine was 0.925mg/kg, rabbits has the greatest gain which is 28% higher than that of control, the difference was significant (P<0.05), at the same time, the body length and skin area were also the greatest and significantly higher than those of the control(P<0.05). There were no significant difference in chest girth, carcass weight, dressing percentage, feed conversion efficiency and survival rate between the control and other groups(P>0.05).(2)Iodine content in diets could affect the blood biochemical indexes of Saibei Rabbit. When rabbits were fed the basic diet in which the practical content of iodine was 0.125mg/kg, the concentrations of Thyroxine(T4), Free Thyroxine(FT4)and Thyroid Hormones(T3)were the lowest, but the concentration of Thyroid-Stimulating hormone(TSH)was the highest. When adding 0.8 mg/kg iodine into diets in which practical content of iodine was 0.925mg/kg, the function of thyroid gland of Saibei Rabbit was the best, the concentrations of T4 , FT4 , T3 were the highest and significantly higher than those of the contro(lP<0.05). But the concentration of TSH was the lowest and significantly lower than that of the control group(P<0.05). This indicated that iodine content in diets could affect the function of thyroid gland of Saibei Rabbit. There were no significant difference between control group and experimental groups in the concentrations of Free Thyroid Hormones(FT3),Alkaline Phosphatase(ALP), Alanine Transaminas(eALT), Asparfic acid Transaminas(eAST), Total protein(TP), Albumin(ALB) and Albumin/Globulin(A/G)(P>0.05). This indicated that iodine content in diets had no effect on the concentrations of FT3, ALP, ALT, AST, TP, ALB and A/ G in Saibei Rabbit.(3)Iodine content in diets had significant positive correlation to the accumulation of iodine in the muscle and liver(r=0.991; r=0.980). With the increasing of iodine content in diet, the iodine content in the muscle and liver increased. When 0.2mg/kg and 0.4mg/kg iodine was added into diets, the iodine content in the muscle and liver was higher than that of the control, but no significant difference was found(P>0.05). When iodine supplementation in diets was more than 0.6mg/kg, there were significant differences in iodine contents in the muscle and liver between the experimental groups and the control (P<0.05).In this experiment, the results was close to the iodine requirement(1.0mg/kg)in meat rabbit feeding standard of French Animal Nutrition Balance Committee(AEC). And these results provided the scientific and theoretical basis for rabbit production in China. |
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