| Zearalenone (ZEA), an estrogenic mycotoxin, is produced mainly by Fusarium fungi. Previous literature had focused on the breeding performance of sows and genitalia of piglets. The effects of ZEA on histopathology in liver, kidney, and spleen, cytology and immunology were limited to in vitro tests and high dose ZEA exposure of laboratory animals. Up to now, the systematic toxicity mechanisms on dose-effect relationship of post-weaning gilts fed diet with low dose ZEA exposure (1.1 to 3.2 mg/kg) have never been observed. Two experiments, therefore, were designed to investigate the genitotoxicity, hepatrenal toxicity, immunotoxicity, and hematotoxicity of dietary ZEA (1.1 to 3.2 mg/kg diet) on post-weaning female pigs. The efficacy of modified montmorillonite in preventing zearalenone-induced adverse effects was also determined.In experiment one, A total of twenty gilts (L×Y×D) at d-35 with an average body weight of 10.36±1.21 kg were used in the study. Gilts were housed in a temperature controlled room, divided to four treatments, and fed individually a corn-soybean meal-fishmeal-whey based diet prepared according to NRC (1998) with an addition of 0, 1, 2, or 3 mg/kg purified ZEA for 18 d ad libitum, respectively. Treatments were control; control + 1 mg/kg ZEA; control + 2 mg/kg ZEA and control + 3 mg/kg ZEA. FE was increased linearly as dietary ZEA concentrations increased (P = 0.049). Relative weights of genital organs and vulva size was increased linearly over 18 d feeding as gilts fed diets containing greater than or equal to 1.1 mg/kg ZEA (P < 0.001). Serum hormones were disordered when ZEA was added at level of 3.0 mg/kg in a dose-dependent manner (P < 0. 05). Histopathology of ovary with lower, smaller ovarian follicle, and corpus uteri tissues with epithelial proliferation were found in the gilts fed greater than or equal to 2.0 mg/kg ZEA-contaminated diet. The anti-apoptosis effect was also observed in the gilts fed greater than or equal to 2.0 mg/kg ZEA-contaminated diet. Relative weights of liver, and kidney were increased linearly (P < 0.05) in a dose-dependent manner. Degeneration of the liver, kidney and spleen tissues was also observed in the gilts fed greater than or equal to 2.0 mg/kg ZEA-contaminated diet. Stress of liver, kidney, spleen and blood was confirmed by the disordered hemocyte, serum enzymes, metabolites, malondialdehyde (MDA) concentrations in both serum and liver (P < 0.05) in a dose- dependent manner. The decreased relative weights of spleen, lymphocyte proliferation rate (LPR) in peripheral blood and spleen, IL-2 production in peripheral blood lymphocyte, CD4~+, CD8~+ and CD4+/CD8+ in peripheral blood, lgG in serum, antibody titer of swine plague, down-regulated expression of INF-γin spleen (P < 0.05) and the up-regulated inflammatory factor expression of IL-1β, IL-6 (P < 0.05) in a dose-dependent manner. It was concluded that the estrogen activity and anabolic action of ZEA (1.1 to 3.2 mg/kg) increased FE of gilts; however, the simultaneous induced genitotoxicity, hepatrenal toxicity, immunosuppression, and hematotoxicity by ZEA were observed.In experiment two, A total of thirty-six postweaning pigs (L×Y×D), half male and half female, with an average of 8.84±0.21 kg were used in the study. The pigs were randomly divided into 6 treatments, and fed individually in a metabolic cage with diets contained with or without 1 mg/kg ZEA (Fermentek, Israel) for 24 days. Different levels of modified montmorillonite (Amlan International, Chicago, USA) were added to feeds to determine its efficacy of preventing ZEA (1.0 mg/kg) toxicity in pigs. Treatments were control; control + 1 g/kg clay; control + 1 mg/kg ZEA; control + 1 mg/kg ZEA + 1 g/kg clay; control + 1 mg/kg ZEA + 2 g/kg clay and control + 1 mg/kg ZEA + 4 g/kg clay. Pigs fed ZEA contaminated diet without modified montmorillonite supplementation showed significant increases of vulva size and reproductive organ weights in female pigs, relative weight of liver and kidney, enzymes, urea and creatinine in serum, MDA in both serum and liver (P < 0.05); however, the decreased relative weight of reproductive organs in male pigs, estradiol in female pigs, relative weight of spleen in female pigs, progesterone and testosterone, glutathione peroxidase (GSHPx) and total superoxide dismutase (SOD) in both serum and liver, serum globulins, triglyceride, high density lipoprotein (HDL), platelet, lymphocyte rato, hemoglobin, CD4+ and CD8+ in peripheral blood, lymphocyte proliferation rate (LPR) in peripheral blood and spleen, IL-2 production in peripheral blood lymphocyte were observed (P < 0.05). A linear lower effect of increased modified montmorillonite on relative weight of reproductive organ and vulva size in female pigs, relative weight of liver, enzymes, urea and creatinine in serum, MDA in both serum and liver (P < 0.05) were observed; however, apparent digestibility of gross energy (GE) and crude protein (CP), NPU, testis size at the end of test, estradiol in female pigs, relative weight of spleen in female pigs, progesterone and testosterone, GSHPx and SOD in both serum and liver, serum IgG, triglyceride, HDL, platelet, lymphocyte rato, hemoglobin, CD4+ and CD8+ in peripheral blood, LPR in peripheral blood, IL-2 production in peripheral blood lymphocyte showed a linear higher effect with increased modified montmorillonite. No treatment effect was obtained on ADG, ADFI, FE, apparent digestibility and availability of nutrient substances; however, a gender effect was observed where female pigs showed lower FE, apparent digestibility and availability of nutrient substances, testosterone and leuteinizing hormone in serum than male pigs (P < 0.05), but male pigs showed lower estradiol, progesterone, all serum enzymes, urea, creatinine in serum, MDA in both serum and liver (P < 0.05). The above findings indicated that ZEA at level of 1.0 mg/kg was sufficient to induce genitotoxicity, hepatrenal toxicity, immunotoxicity, and hematotoxicity of piglets. Addition of 2 to 4 g modified montmorillonite adsorbent /kg diet in 1.0 mg/kg ZEA contaminated diet can effectively protect against the detrimental effects of the ZEA feeding. A gender effect was observed where female pigs showed significant toxicity than male pigs.In conclusion, the present study indicated that ZEA exposure at about 1.0 to 3.2 mg/kg induced a progressively significant genitotoxicity, hepatrenal toxicity, immunotoxicity, and hematotoxicity in pigs. The evident detoxification effect was observed when addition of 4 g modified montmorillonite adsorbent /kg diet in 1.0 mg/kg ZEA contaminated diet. The effect on female pigs was more serious than male pigs. These results may have implications for humans health and animals production consuming ZEA-contaminated food or feed. |
PDF Full Text Request