肉仔鸡饲粮中锌需要量的研究

A STUDY ON Zn REQUIREMENT FOR BROILERS

取1日龄AA肉仔鸡600只,公、母各300只,随机分为10组,公、母各5组,每组4个重复,分别喂以含锌40mg/kg的基础日粮和含锌50、70、90和110mg/kg的添加锌日粮,以研究肉仔鸡对锌的需要量。试验期8周。结果表明,6周龄前日粮锌各水平对公、母鸡的体增重和饲料报酬无明显差异(P>0.05),40mg/kg锌可满足其生长需要。7周龄后,虽然公、母鸡分别在日粮含锌50和90mg/kg时可达到最大体增重,但差异不显著(P>0.05)。对于组织中的锌含量,不同组织、不同生长阶段对日粮补锌的反应不同。公、母鸡血液中锌含量并不随日粮锌含量的增加而升高;肾脏锌含量变化也不大;比较敏感的组织是胰和肝。组织锌含量依次为胰>肝>肾>血。血液中的碱性磷酸酶活性公、母鸡不同,但总的看来,随日龄增加而降低。铜锌超氧化物歧化酶(CuZnSOD)的活性不同组织、不同生长阶段和不同性别是不同的,母鸡比公鸡的酶活性高。根据各项指标的测定结果和经济效益综合分析,建议肉仔鸡对锌的需要量为40～50mg/kg。

600 one day - old AA broilers(300 and 300) were randomly allotted into 10 groups(5 male and 5 female groups),and each group had 4 duplicates,and was fed with a basal,diet containing 40mg Zn/kg,and a Zn - supplement of 50,70,90 or 110mg of Zn/kg was added,to study Zinc requirement.The trial period was;8 weeks.The results showed that the Zn requtre ments for broilers were different according to sexes and growth stages.Before 6 weeks of age,dietary Zn levels did not have significant effect on bodyweight gains and feed conversion rate between sexes(P>0.05),and 40 mg of dietary Zn/kg could meet the need.Rut after 7 weeks of age,the greatest weight gains in male and female were in the 50 and 90 mg Zn/kg groups,respectively.The Zinc - supplemental responces in the Zn contents in tissues differed in different tissues and growth stages.The sensitive tissues to the dietary zinc levels were pancreas and liver,which showed a rising trend with the increased zinc content.The highest zinc contents in tissues were 90 and 110 mg Zn/kg for male and female groups,respectively.The tissue sequence for their zinc contents was pancreas > liver > kidney > blood.The highest activity of AKP(Alkaline Phosphatase) appeared in 70mg Zn/kg group.The activity of CuZnSOD was variable in different tissues,and the activity in female was higher than that in male.CuZnSOD value in blood was the highest when diet contained 70 mg Zn/kg,while that in liver was the lowest.Meanwhile the value would rise when dietary zinc levels increased and the value reached the top as male was fed with 90 and female with 110 mg Zn/kg.From the results, we suggested that the Zinc requirement for broilers should be 40 before 6 weeks of age and 90mg Zn/kg after 7 weeks of age.