嘔吐毒素對臺灣土雞性能之影響

Abstract

本研究旨在探討嘔吐毒素（deoxynivalenol, DON）對於臺灣土雞性能之影響。試驗使用208隻5日齡黑羽臺灣土雞，採公母混養並逢機分配至四個餵飼處理組，分別給飼含0、2、5及10 ppm嘔吐毒素濃度之飼糧。餵飼試驗為期16週並劃分成三期，分別為5-21日齡、22-70日齡及71-112日齡，於各期結束時進行採樣及犧牲。研究結果顯示，雖於第二期期間，5及10 ppm組之公和母雞體增重差距擴大，然試驗全期之生長表現並無顯著差異。血液生化值如血清天冬胺酸轉胺酶（aspartate transaminase, AST）、丙胺酸轉胺酶（alanine transaminase, ALT）、尿酸（uric acid, UA）及免疫球蛋白A（immunoglobulin, IgA）濃度並未受嘔吐毒素濃度影響，嘔吐毒素對於心臟及肝臟之相對重量亦無顯著影響，然於試驗結束時，餵飼5 ppm組雞隻之脾臟相對重量顯著較對照組增加（P < 0.05），而10 ppm組除母雞脾臟組織之增生細胞（proliferating cell nuclear antigen, PCNA）數目顯著減少，而公雞被促進增生外，其脾臟組織之細胞凋亡增加（TUNEL分析）及DNA損傷加劇（γ-H2AX）（P < 0.05）。在腸道方面，除5 ppm組有部分公雞之迴腸顯現絨毛異常短小的現象外，絨毛型態上各組間並沒有顯著差異。而在攸關腸道障壁之空腸緊密連接蛋白claudin-5的表現量上，2及5 ppm組之母雞呈顯著增加，然而公雞表現量則顯著被抑制（P < 0.05）。綜述論之，10 ppm以下嘔吐毒素汙染之飼糧對臺灣土雞生長性狀無顯著影響，然而本研究結果顯示，長期暴露於高濃度嘔吐毒素危害下，雞隻之免疫系統會被刺激，進而可能造成免疫器官的損傷，嘔吐毒素藉由調控緊密連接蛋白表現量以改變腸道障壁功能，而腸道障壁的毀損可能助長病原的入侵，進而提高雞隻對傳染性疾病之感受性。關於嘔吐毒素對家禽長期性的影響，仍需未來進行多方研究以更深入探討。

The objective of this study was to investigate the impact of deoxynivalenol (DON) on the growth performance of Taiwan country chickens. Two hundred and eight 5-d-old black-feathered Taiwan country chickens were randomly assigned to 4 treatments, 0, 2, 5 and 10 ppm DON. The experiment lasted for 16 weeks and was divided into three intervals, 5-21 d, 22-70 d, and 71-112 d. Results indicated that although the difference of body weight gain between male and female birds widened during the second phase in treatments fed diets containing high levels of DON, the overall growth performance was not significantly different. None of the blood biochemistry (serum ALT, AST, UA and IgA) responded to increased DON levels in the diet. DON had no adverse effects on relative organ weights except that relative weights of spleen in birds fed 5 ppm DON diet increased compared with that of controls (P < 0.05). Increasing proliferation (proliferating cell nuclear antigen, PCNA), higher levels of apoptosis (TUNEL assay), and DNA damage (γ-H2AX) were observed in immunohistochemistry of the spleen sections in 10 ppm DON treatment (P < 0.05), except that female birds had decreased proliferation index. There were no significant differences in intestinal morphology, whereas the length of villus in ileum tended to be shorter among birds fed diets containing low levels of DON. The expression of tight junction protein, claudin-5, increased in some female birds fed 2 and 5 ppm DON, while in male birds, it appeared to have decreased expression levels (P < 0.05). In conclusion, Taiwan country chickens seemed to possess high tolerance to DON contaminated diets. Nevertheless, our results show that DON may cause disturbance to the immune system and impair the barrier function of the intestine, leading to higher susceptibility to infectious disease. Further investigation on the long-term effect of DON is required to confirm these findings.