Sandoval M, Henry P R, Luo X G, Littell R C, Miles R D, Ammerman C B
Department of Animal Science, University of Florida, Gainesville 32611-0900, USA.
Poult Sci. 1998 Sep;77(9):1354-63. doi: 10.1093/ps/77.9.1354.
Four experiments were conducted to identify several factors that might improve the accuracy and reproducibility of Zn bioavailability assays for chicks. Response of tissue Zn and metallothionein (MT) concentrations to various elevated levels and soluble sources of dietary Zn were measured, as well as the effect of delaying high Zn administration until 7 d posthatching to alleviate the detrimental effect of Zn sulfate on feed intake to 3 wk of age. Bone Zn increased (P < 0.01) in all experiments in response to increasing dietary Zn concentrations. Liver and pancreas MT were affected (P < 0.01) by a source by age interaction and variability that made this criterion unsuitable for bioavailability assays. Lastly, 1-d-old chicks were used to study the effect of delaying feeding of a high-Zn diet up to 7 d of age. The basal diet was fed continuously for 21 d as a control. A diet containing 1,000 ppm Zn was either fed continuously from Day 1, or started on Day 3, 5, or 7. Chicks given high Zn on Day 3, 5, or 7 decreased (P < 0.01) feed intake within 24 h of feeding. Delayed feeding of high dietary Zn might help to alleviate decreased feed intake observed in previous studies. Delaying the onset of high Zn feeding by several days may help alleviate feed intake problems observed with Zn sulfate. Use of either Zn gluconate or Zn acetate as a standard in assays or use of MT synthesis as a bioavailability criterion will probably not be useful to improve accuracy of the estimates.
进行了四项实验，以确定可能提高雏鸡锌生物利用率测定准确性和可重复性的几个因素。测量了组织锌和金属硫蛋白（MT）浓度对各种升高水平和膳食锌可溶性来源的反应，以及将高锌给药推迟至孵化后7天以减轻硫酸锌对3周龄采食量的有害影响。在所有实验中，随着日粮锌浓度的增加，骨锌含量增加（P<0.01）。肝脏和胰腺MT受到来源与年龄交互作用和变异性的影响（P<0.01），这使得该标准不适用于生物利用率测定。最后，使用1日龄雏鸡研究将高锌日粮的饲喂推迟至7日龄的影响。基础日粮连续饲喂21天作为对照。含1000 ppm锌的日粮要么从第1天开始连续饲喂，要么在第3、5或7天开始饲喂。在第3、5或7天给予高锌的雏鸡在饲喂后24小时内采食量下降（P<0.01）。推迟高锌日粮的饲喂可能有助于减轻先前研究中观察到的采食量下降。将高锌饲喂的开始时间推迟几天可能有助于缓解硫酸锌引起的采食量问题。在测定中使用葡萄糖酸锌或乙酸锌作为标准，或使用MT合成作为生物利用率标准，可能无助于提高估计的准确性。
