Hampton D L, Miller W J, Neathery M W, Kincaid R L, Blackmon D M, Gentry R P
J Dairy Sci. 1976 Nov;59(11):1963-6. doi: 10.3168/jds.S0022-0302(76)84469-4.
Calves fed a high-zinc diet were used to study zinc absorption from various sections of the small intestine. Absorption was determined by measuring zinc-65 in various tissues and plotting the tissue concentrations against dosing site, expressed as percentage of intestinal length. Zinc absorption, per unit of intestinal length, was similar throughout the small intestine and was as great in the distal as in the proximal end. Apparently, early researchers using isolated loops and everted sac techniques failed to recognize rate of digesta passage and tissue homeostasis as major factors associated with zinc uptake when they concluded that the duodenum was the primary site of zinc absorption. The data show that the duodenum is not the major site of zinc absorption in calves regardless of dietary zinc. In a separate experiment, zinc-65 was injected directly into the large intestine of calves fed a low zinc diet. Only about 2% of total zinc absorption was from the large intestine.
用喂食高锌日粮的犊牛来研究小肠各段对锌的吸收情况。通过测量各组织中的锌-65含量，并将组织浓度与给药部位（以肠长度的百分比表示）作图来确定吸收情况。每单位肠长度的锌吸收在整个小肠中相似，远端和近端一样高。显然，早期使用离体肠袢和外翻肠囊技术的研究人员在得出十二指肠是锌吸收的主要部位这一结论时，未能认识到消化物通过速率和组织内稳态是与锌摄取相关的主要因素。数据表明，无论日粮锌含量如何，十二指肠都不是犊牛锌吸收的主要部位。在另一个实验中，将锌-65直接注入喂食低锌日粮的犊牛大肠中。总锌吸收中只有约2%来自大肠。
