ABSTRACT

Zinc (Zn), an important microelement in ruminant diet, plays a critical role in various enzymes, hormones and functional proteins involved in nutrient metabolism. The present study was conducted to assess the effect of zinc hydroxychloride (Zn₅(OH)₈Cl₂·H₂O [ZnOHCl] and zinc sulphate (ZnSO₄) on nutrient utilisation, mineral metabolism and biomarkers pertaining to growth performance in pre-ruminant crossbred calves. Twenty-four crossbred calves [body weight (BW); 31.03 ± 4.30 kg; age 10 d] were randomly allocated to four treatment groups (n = 6), i.e. no supplementation of Zn (0 mg/kg dry matter [DM]), 80 mg/kg DM Zn as ZnSO₄(ZnS-80), 40 mg/kg DM Zn as ZnOHCl (ZnH-40) and 80 mg/kg DM Zn as ZnOHCl (ZnH-80) for 90 d experimental period. Results showed that dietary Zn supplementation improved (p < 0.05) feed intake, BW, average daily gain, heart girth, body length, plasma growth hormone, insulin-like growth factor and thyroxin concentration; however, nutrient digestibility remained unaffected among the groups. Addition of Zn increased (p < 0.05) Zn retention and plasma Zn concentration without affecting retention and plasma concentration of other minerals. Retention of Zn was the highest in ZnH-80 group followed by ZnH-40, ZnS-80 and lowest in control group. Overall results of the present study indicate that regardless of sources and levels, Zn supplementation increased growth performance, plasma Zn concentration and hormones levels in pre-ruminant crossbred calves. However, supplementation of hydroxy Zn at 40 mg/kg DM had similar effect as produced by ZnSO₄ or ZnOHCl at a supplementation level of 80 mg/kg DM. Therefore, from the present study it can be concluded that ZnOHCl can be used as a Zn source for pre-ruminant calves at a lower dose compared to ZnSO₄.

摘要

锌（Zn）是反刍动物日粮中重要的微量元素，在参与营养代谢的各种酶、激素和功能蛋白中起着至关重要的作用。本研究旨在评估羟基氯化锌 (Zn ₅ (OH) ₈ Cl ₂ ·H ₂ O [ZnOHCl] 和硫酸锌 (ZnSO ₄ ) 对养分利用、矿物质代谢和生物标志物的影响。反刍杂交小牛. 24 头杂交小牛 [体重 (BW); 31.03 ± 4.30 kg; 10 天] 被随机分配到四个处理组 ( n = 6)，即不补充锌 (0 mg/kg 干物质[DM]), 80 mg/kg DM Zn 作为 ZnSO ₄(ZnS-80)、40 mg/kg DM Zn 作为 ZnOHCl (ZnH-40) 和 80 mg/kg DM Zn 作为 ZnOHCl (ZnH-80) 进行 90 天的实验期。结果表明，日粮补锌提高了（p < 0.05）采食量、体重、平均日增重、心围、体长、血浆生长激素、胰岛素样生长因子和甲状腺素浓度；然而，各组之间的营养消化率仍然不受影响。锌添加量增加 ( p< 0.05) Zn 保留和血浆 Zn 浓度，而不影响其他矿物质的保留和血浆浓度。Zn的保留以ZnH-80组最高，其次是ZnH-40、ZnS-80，对照组最低。本研究的总体结果表明，无论来源和水平如何，补锌都能提高反刍前杂交小牛的生长性能、血浆锌浓度和激素水平。然而，添加 40 mg/kg DM 的羟基锌与添加 80 mg/kg DM 的 ZnSO ₄或 ZnOHCl 产生的效果相似。_{因此，从本研究可以得出结论，与 ZnSO 4}相比，ZnOHCl 可用作反刍小牛的 Zn 源，其剂量较低。