单胃动物对不同来源锌利用的研究

用饲养、平衡、屠宰法测试蛋雏、蛋鸡、内雏与断奶大鼠对不同水平或来源锌的利用、沉积及一些因素,如钙、纤维、植酸水平的影响。采食量、增重量与产蛋量不敏感;空体或全血锌含量亦非有效指标。肝、胰、胫骨及中掌骨的锌浓度,随采食锌水平而规律性地变动,但须进一步量化。血清磷酸酶活性亦表现变动趋势,有待肯定。过量植酸与纤维均增加锌的排泄量,锌的利用率与沉积率都随采食量而下降,并非固定值。建议在常用锌的需要量条件(如50mg/kg 下)测定锌的绝对生物效价,然后采用以 ZnSO_4·7H_2O 为参照物,测定其它锌源的相对生物效价。

ON THE BIOAVAILABILITY OF ZINC FOR MONOGASTRICS

Bioavailability of zinc at various levels and from different sources was assessed on egg-type starters and layers,broilers and weanling rats using the feeding,balance and com- parative slaughter methods with feed intake,growth rate,blood parameters,whole body and tissue utilization and retention rates as criteria.Special attention was paid to the bilateral ef- fects of phytic acid and zinc levels.Growth and laying performances were insensitive,nor were empty body zinc retention rate or Whole blood zinc concentration.Liver,pancreas and tibial or metacarpal zinc concentrations and serum AKP activity showed promise because of their curvilinear or linear changes following gradient increase in zinc level although further inquiries should be conducted. Excessive phytic acid depressed zinc utilization mainly due to increased zinc excretion. Both absolute and relative bioavailabilities should be determined in order to assess the utilizability of zinc.Differences were found among zinc compounds and zinc from various feed sources.Proposals were suggested for determination of zinc availability.