Effects of zinc oxide-montmorillonite hybrid on growth performance, intestinal structure, and function of broiler chicken

A total of 450 one-day-old Arbor Acres male chickens were used to investigate the effects of zinc oxide-montmorillonite hybrid (ZnO-MMT) on growth performance, intestinal structure, and function. The birds were allotted to 5 dietary treatments for 21 d, each of which was replicated 6 times with 15 chicks per replicate. The dietary treatments were 1) corn-soybean meal diet (basal, containing 42.35 mg of Zn/kg); 2) basal diet + 600 mg of MMT/kg (equivalent to the MMT in the ZnO-MMT treatment); 3) basal diet + 60 mg of Zn/kg as ZnO; 4) basal diet + 60 mg of Zn/kg as ZnO-MMT; and 5) basal diet + 60 mg of Zn/kg as ZnSO(4)•7H(2)O. The results showed that chicks fed ZnO-MMT had higher (P < 0.05) ADG and feed intake than those fed the basal diet, MMT, or ZnO. Compared with the control, MMT, ZnO, or ZnSO(4), supplementation with ZnO-MMT decreased (P < 0.05) viable counts of Clostridium in small intestinal and cecal contents, increased (P < 0.05) colonic transepithelial electrical resistance (TER) values, and reduced (P < 0.05) colonic probe mannitol permeability as well as ileal or colonic inulin permeability. Compared with the control, supplemental ZnO-MMT increased (P < 0.05) villus height, the ratio of villus height to crypt depth at the small intestinal mucosa, the trypsin activity in the pancreas, and the digestive enzyme activities in small intestinal contents. Compared with the control, supplementation with ZnO increased (P < 0.05) the villus height and the villus height to crypt depth ratio at the duodenum. Supplementation with ZnSO(4) increased the trypsin activity in pancreas and small intestinal contents. However, supplemental MMT, ZnO, or ZnSO(4) did not affect (P > 0.05) growth performance, ileal and colonic barrier function, and intestinal microflora. The results indicated that supplementing 60 mg of Zn/kg as ZnO-MMT in broiler chickens improved growth performance, intestinal microflora, intestinal morphology, and barrier function as well as the digestive enzyme activities.

[Establishment and experimental study of a transplantable hepatocellular carcinoma model in 615-strain mice (H 615)]

H 615, the first transplantable mouse liver carcinoma model established in China, was derived from a spontaneous hepatocellular carcinoma of an inbred 615 mouse and has been successfully propagated for 52 generations during the past 7 years and more. Its biologic and pathologic features are relatively stable. H 615 was a syngenic transplantable tumor model of 615-strain mice with a successful transplantation rate of 85.6% without spontaneous regression. The course of tumor growth after subcutaneous inoculation was divided into 4 stages: latent, slowly growing, rapidly growing and terminal stages. Cancer metastasis was rare. The tumor-bearing host would die of cachexia finally. The mean survival time was 62.2 +/- 11.0 days regardless of sex or age. Histologically and ultrastructurally, H 615 was a well-differentiated hepatocellular carcinoma, rather resembling human liver carcinoma. The short-term primary passage culture of H 615 showed that, in vitro, tumor tissue could easily grow into monolayer, the majority of which appeared as epithelioid cells in cytomorphology. Therapeutic tests of 15 anticancer drugs showed that H 615 was sensitive, in varying degrees, to 5 drugs, i. e. MMC, Thio-Tepa, 5FU, CPT and DACT. The inhibition rate of MMC and Thio-Tepa could be as high as 100%. These experimental results are similar to those of the human liver cancer chemotherapy. Hence, the authors believe that H 615 may be a useful model in experimental study of the liver cancer and screening of anticancer drugs.