ABSTRACT

1. The bioavailability of a trace mineral source is related to its intestinal solubility (bioaccessibility), which in turn is determined by its physicochemical properties. It is still not clear which characteristics are more relevant in affecting solubility and bioavailability of mineral sources. Zinc oxide (ZnO) is a common feed additive used to supplement zinc in the diet of monogastric animals. However, different sources have shown variable responses on animal bioavailability.

2. This study hypothesised that different sources of feed grade ZnO have various physicochemical features that lead to distinct bioavailability values. Feed grade ZnO samples collected from the feed industry worldwide were characterised for their physicochemical features and tested in broilers to allow bioavailability determined.

3. A total of 135 male Cobb broiler chickens were fed a standard starter diet from day 1 after hatching up to d 7. At d 8, animals were allocated in individual cages and fed one of the following dietary treatments during 15 days: a basal diet with 23.5 ppm of zinc and seven test diets with supplemented ZnO or zinc sulphate (ZnSO₄) at 6 or 12 ppm.

4. Different sources of ZnO showed an effect of solubility in the stomach and supplementation influenced total Zn levels in the ileum. The bioavailability of the different sources varied from 49% to 160% in relation to ZnSO₄. Aggregate size of particles seems to explain most of the variability in the bioavailability of the different sources tested in broilers. In conclusion, physicochemical properties of ZnO can partly explain the variability observed in terms of biological value.

摘要

1. 微量矿物质来源的生物利用度与其肠道溶解度（生物可及性）有关，而后者又取决于其物理化学性质。目前尚不清楚哪些特征与影响矿物来源的溶解度和生物利用度更相关。氧化锌 (ZnO) 是一种常见的饲料添加剂，用于在单胃动物的饮食中补充锌。然而，不同的来源对动物的生物利用度表现出不同的反应。

2. 本研究假设不同来源的饲料级 ZnO 具有不同的物理化学特征，从而导致不同的生物利用度值。从全球饲料行业收集的饲料级 ZnO 样品对其物理化学特征进行了表征，并在肉鸡中进行了测试，以确定生物利用度。

3. 从孵化后的第 1 天到第 7 天，总共 135 只雄性 Cobb 肉鸡被喂食标准的起始日粮。在第 8 天，动物被分配到单独的笼子中，并在 15 天内喂食以下一种日粮处理：含 23.5 ppm 锌的日粮和 7 种添加6 或 12 ppm ZnO 或硫酸锌 (ZnSO ₄ ) 的试验日粮。

4. 不同来源的 ZnO 显示出在胃中溶解度的影响，并且补充剂影响回肠中的总 Zn 水平。相对于 ZnSO ₄，不同来源的生物利用度从 49% 到 160% 不等。颗粒的总大小似乎可以解释在肉鸡中测试的不同来源的生物利用度的大部分变化。总之，ZnO 的物理化学性质可以部分解释在生物学价值方面观察到的变异性。