Wedekind K J, Hortin A E, Baker D H
Department of Animal Science, University of Illinois, Urbana 61801.
J Anim Sci. 1992 Jan;70(1):178-87. doi: 10.2527/1992.701178x.
The bioavailability of zinc-methionine (ZnMET) was compared to that of feed-grade ZnSO4.H2O using three different diets: purified (crystalline amino acid [AA]), semipurified (soy isolate), and complex (corn-soybean [C-SBM]) diet. With the Zn-deficient purified or semipurified diet, weight gain and tibia Zn responded linearly to both ZnSO4.H2O and ZnMET supplementation. Common-intercept, multiple linear regression indicated differences in Zn bioavailability between ZnMET and ZnSO4.H2O for both diets as indicated by bone Zn. With the ZnSO4.H2O standard set at 100%, bioavailability of Zn from ZnMET was 117% (P less than .05) in the AA diet and 177% (P less than .01) in the soy isolate diet. The ZnMET was also compared to ZnSO4.H2O in a C-SBM diet containing 117 mg of Zn/kg. When high levels of Zn were added to this diet (0, 250, 500, and 750 mg/kg of supplemental Zn), consistent tissue Zn responses did not occur beyond the first increment. Addition of lower levels of supplemental Zn (0, 5, 10, 20, 30, 40 and 50 mg/kg) to a Zn-unsupplemented C-SBM basal diet (45 mg/kg of Zn), however, resulted in a broken-line, two-slope response in tibia Zn for both ZnMET and ZnSO4.H2O. Inflection points occurred at 60 and 54 mg of Zn/kg of diet for ZnSO4.H2O and ZnMET, respectively. The ratio of slopes (ZnMET:ZnSO4.H2O) below the inflection points was 206% (P less than .01), indicating that Zn was considerably more bioavailable in ZnMET than in ZnSO4.H2O for chicks consuming C-SBM diets. When feed-grade ZnO was compared to feed-grade ZnSO4.H2O in chicks consuming C-SBM diets, bone Zn slopes below the respective inflection points indicated that Zn was 61% bioavailable in ZnO relative to ZnSO4.H2O.
使用三种不同的日粮比较了蛋氨酸锌（ZnMET）与饲料级硫酸锌一水合物（ZnSO4·H2O）的生物利用率：纯化日粮（结晶氨基酸[AA]）、半纯化日粮（大豆分离蛋白）和复合日粮（玉米-豆粕[C-SBM]）。对于缺锌的纯化或半纯化日粮，体重增加和胫骨锌含量对补充ZnSO4·H2O和ZnMET均呈线性反应。共同截距多元线性回归表明，两种日粮中ZnMET和ZnSO4·H2O之间的锌生物利用率存在差异，如骨锌所示。以ZnSO4·H2O标准设定为100%，在AA日粮中，ZnMET中锌的生物利用率为117%（P<0.05），在大豆分离蛋白日粮中为177%（P<0.01）。在含锌量为117mg/kg的C-SBM日粮中，还将ZnMET与ZnSO4·H2O进行了比较。当向该日粮中添加高水平的锌（0、250、500和750mg/kg的补充锌）时，除了第一次增量外，未出现一致的组织锌反应。然而，在未添加锌的C-SBM基础日粮（锌含量为45mg/kg）中添加较低水平的补充锌（0、5、10、20、30、40和50mg/kg），导致ZnMET和ZnSO4·H2O的胫骨锌含量均出现折线双斜率反应。ZnSO4·H2O和ZnMET的转折点分别出现在日粮锌含量为60和54mg/kg时。转折点以下的斜率比（ZnMET:ZnSO4·H2O）为206%（P<0.01），表明对于食用C-SBM日粮的雏鸡，ZnMET中的锌比ZnSO4·H2O中的锌生物利用率高得多。当在食用C-SBM日粮的雏鸡中将饲料级氧化锌与饲料级硫酸锌一水合物进行比较时，各自转折点以下的骨锌斜率表明，相对于ZnSO4·H2O，氧化锌中锌的生物利用率为61%。
