Effects Of Dietary Met-Zn Levels On Growth Performance, Antioxidase Activity And Metallothionein-1 Expression Of New Zealand Rabbits

The purpose of this trial was to study the effects of dietary ZnSO4 and Zn-Met levels on the production performance, serum and liver CuZn-SOD, GSH-Px activities, MDA concentration, Zinc Tissue Retention and MT-1mRNA expression of 2~3 month-old New Zealand growing rabbits. One hundred and forty weaned New Zealand rabbits were randomly allotted to seven treatments of twenty rabbits each, in which they were fed each diet with Zn levels(0 mg/kg,40 mg/kg,80 mg/kg,120mg/kg)and Zn sources(ZnSO4 and Zn-Met). The results were as follows:Experiment one: Different dietary Zn-Met levels had significant effect on average daily gains(ADG)(P<0.05), 80mg/kg Zn-Met group ADG was highest and different dietary ZnSO4 or Zn-Met levels had no significant effect on average daily intake(ADI), feed/gain(F/G)(P>0.05); different dietary zinc levels had significant effect on thymus weight, thymus index and spleen weight(P<0.05); The different dietary Zn levels or Zn sources could extreme improve serum CuZn-SOD activities(P<0.01), improve GSH-Px activities and cut down MDA concentration(P<0.05) and extreme improve liver GSH-Px activities(P<0.01), improve CuZn-SOD activities and cut down MDA concentration(P<0.05), with the dietary zinc level increased from 80mg/kg to 120mg/kg, the activity of CuZn-SOD and GSH-Px increased ZnSO4 treatment and decreased Zn-Met treatment; different dietary zinc levels could extreme improve serum AKP activities(P<0.01); different dietary ZnSO4 or Zn-Met levels could significant increase Zn concentration in liver, spleen, kidney, pancreas, serum, and tibia; Liver, serum, pancreas, spleen concentration and AKP activity could reflect the zinc concentration of dietary when supplement zinc within 120mg/kg. The different dietary Zn levels or Zn sources could extreme significant effect MT-1mRNA expression in liver and kidney(P<0.01);With the increase of Zn levels, MT-1mRNA expression in liver and kidney increased ZnSO4 treatment, when supplement levels of Zn was 80mg/kg, Zn-Met treatment liver and kidney MT-1mRNA expression was highest. In conclusion, the appropriate dietary ZnSO4 level to weaned-2month-old rabbits was 80~120mg/kg and Zn-Met level was 80mg/kg.Experiment two: The results showed that: different dietary ZnSO4 or Zn-Met levels had no significant effect on ADG, F/G(P>0.05)and had significant effect on ADI(P<0.05); With the increase of Zn levels, ADI increased ZnSO4 treatment, when supplement levels of Zn was 80mg/kg, Zn-Met treatment ADI was highest. The different dietary Zn levels or Zn sources had no significant effect on dressing percentage(P>0. 05); The dietary zinc level could improve thymus weight, thymus index, spleen weight and spleen index(P<0.05), but there no significant different between 80mg/kg and 120mg/kg of dietary zinc level; The dietary Zn supplement could improve serum CuZn-SOD, GSH-Px activities(P<0.05) and extreme improve liver CuZn-SOD, GSH-Px activities(P<0.01); different dietary zinc levels could extreme improve serum AKP activities(P<0.01); different dietary ZnSO4 or Zn-Met levels could significant increase Zn concentration in heart, liver, spleen, kidney, pancreas, serum, tibia, liver, serum, pancreas, spleen, tibia zinc concentration and AKP activity could reflect the zinc concentration of dietary when supplement zinc within 120mg/kg; With the increase of Zn levels, MT-1mRNA expression in liver and kidney increased and then decreased, when supplement levels of Zn was 80mg/kg, ZnSO4 or Zn-Met treatment liver and kidney MT-1mRNA expression was highest. In conclusion, the appropriate dietary ZnSO4 or Zn-Met level to weaned-2month-old rabbits was 80mg/kg.