【作者】 杨军；

【导师】 柏凡； 张克英；

【作者基本信息】 四川农业大学 ， 动物营养与食品工程， 2012， 硕士

【摘要】 本试验旨在探讨自然霉变玉米对肉鸡生产性能和健康的影响及霉菌毒素在肉鸡组织中的残留量。试验采用单因子完全随机区组设计。生长前期(1-21d)和生长后期(22-42d)肉鸡基础饲粮中玉米分别占60.00%和63.00%,各处理饲粮中自然霉变玉米替代非霉变玉米的比例分别为0、25%、50%、75%和100%。选取1200只1日龄COBB500肉仔鸡公雏,按体重分为5个处理,每个处理8个重复,每个重复30只鸡。试验共42d,分为生长前期和后期两个阶段。生长试验结束后,各重复选择1只鸡进行代谢试验,试验期1周。试验第22d和43d按平均体重每个重复选择2只鸡,颈静脉采血,测定血液生化指标；采血后屠宰,分离十二指肠、空肠、回肠,测定其绒毛高度、隐窝深度,并计算二者比值；取肝脏样品,测定肝脏组织中蛋白、丙二醛(MDA)含量和谷胱甘肽还原酶(GR)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、谷胱甘肽-S-转移酶(GST)活性以及肝脏总抗氧化能力(T-AOC);对肝脏进行组织病理学、超微结构观察以及细胞凋亡率(AR)测定；测定肝脏和胸肌中黄曲霉毒素B1(AFB1)以及其代谢产物黄曲霉毒素M1(AFM1)的残留量。结果如下：(1)与对照组相比,随霉变玉米替代比例增加,肉鸡21d体重、前期体增重和采食量显著降低,料肉比升高(P<0.05)；100%霉变组肉鸡42d体重、全期体增重、后期采食量以及75%、100%霉变组肉鸡全期采食量显著降低(P<0.05)。(2)自然霉变玉米显著降低21d肉鸡十二指肠绒毛高度以及21d和42d肉鸡十二指肠、空肠、回肠绒毛高度与隐窝深度的比值,升高42d肉鸡十二指肠隐窝深度(P<0.05),有降低空肠、回肠绒毛高度和升高隐窝深度的趋势。(3)自然霉变玉米对钙磷表观利用率无显著影响,但有降低干物质、有机物、粗蛋白和总能表观利用率的趋势(P>0.05)。(4)75%、100%霉变组肉鸡肝脏相对重量有提高的趋势(P>0.05)；自然霉变玉米显著影响肉鸡21d血清AST、γ-GT活性(P<0.05),对21d血清TP、ALB、ALT以及42d血清TP、ALB、ALT、AST、γ-GT无显著影响(P>0.05)。(5)自然霉变玉米显著降低肉鸡21d肝脏蛋白含量、GSH-Px活性(P<0.05),提高MDA含量以及GR、SOD、GST活性(P<0.05)；显著降低42d肝脏蛋白含量(P<0.05),提高GR、SOD、GST活性(P<0.05)以及MDA含量(P=0.056)。(6)自然霉变玉米造成肉鸡肝脏组织损伤以及超微结构改变,随霉变玉米替代比例增加,肝脏组织病变程度加深,细胞凋亡率显著升高(P<0.05)；对照组、25%、50%、75%、100%霉变玉米组肉鸡21d和42d肝脏病理学评分分别为0、0.67、0.83、1.83、3.67和0、0、0.17、0.33、0.50。(7)在50%和100%霉变组肉鸡肝脏检出AFB1及其代谢产物AFM1残留,胸肌检出AFB1残留,肝脏AFB1残留量为0.049和0.137μg/kg,AFM1残留量为0.033和0.051μg/kg；胸肌AFB1残留量为0.015和0.0161μg/kg,AFM1未检出。上述结果表明,前期肉鸡饲粮霉变玉米替代比例达50%以上、后期达100%(前期饲粮AFB1：36.9-82.4μg/kg；后期饲粮AFB1：134μg/kg)时,显著降低肉鸡生产性能,影响肠道发育,损伤肝脏结构及功能；肝脏检出AFB1和AFM1残留,胸肌检出AFB1残留,且肝脏残留量大于胸肌,并随霉变玉米比例增加而增加。更多还原

【Abstract】 This study was conducted to evaluate the effects of corn naturally contaminated with mycotoxin on growth performance, health and aflatoxin residues in broilers. A total of1200COBB500male broiler chicks were randomly allocated into5groups with8replicates per groups and30birds per replicates involving a single factorial experiment design. The experiment lasted for6weeks and five dietary treatments included basal diet containing60.00%and63.00%corn for the starter (1-21d) and grower (22-42d) period respectively, and25%,50%,75%corn100%corn naturally contaminated with mycotoxin substitute for the appropriate corn in the basal diet. The nutrients digestibility experiment was conducted after growth experiment. On day22and day43, two birds of each replicate were choosed and got10ml blood through the jugular vein. And then, the birds were killed, and the duodenum, jejunum and ileum were selected. The villus height and crypt depth of duodenum, jejunum and ileum were determined, and the ratios of villus height to crypt depth were calculated. Serum total protein (TP) and albumin (ALB) contents, alanine transaminase (ALT), aspartate aminotransferase (AST) and γ-glutamyltransferase (γ-GT) enzyme activities were measured; the contents of total protein (TP), malondialdehyde (MDA), activities of glutathione reductase (GR), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione-S-transferase (GST), and total antioxidant capacity (T-AOC) in liver tissues were measured; liver samples were taken for the examination of histopathology and ultrastructure and the determination of apoptosis rate; the residues of AFB1and AFM1in livers and breast muscles were analyzed by LC-MS/MS; feed and excreta samples collected from digestibility experiment were analyzed for dry matter, organic matter, crude protein, calcium and phosphorus and gross energy.The results showed that body weight (BW), body weight gain (BWG) and feed consumption (FC) significantly decreased and the feed gain ration (F/G) significantly increased on day21(P<0.05) as the ratio of contaminated corn increased. Compared with control, BW of day42, FC from day22to42and BWG from day1to42significantly decreased in100%contaminated group, FC significantly decreased from day1to42for75%and100%contaminated groups (P<0.05).Corn naturally contaminated with mycotoxin significantly decreased villus height in the duodenum on day21, increased crypt depth in the duodenum on day42, and decreased the ratios of villus height to crypt depth in the duodenum, jejunum and ileum on day21and day42(P＜0.05).No significant difference was found on the apparent digestibilitiy of calcium and phosphorus, but there was a tendency in decreasing apparent digestibility of dry matter, organic matter, crude protein and gross energy of the broilers fed diets with75%and100%contaminated corn (P>0.05).Compared with control,75%and100%contaminated corn tended to increased the relative weight of liver (P>0.05). Corn naturally contaminated with mycotoxin significantly affected the activities of serum AST and y-GT on day21, and no significant difference was observed for TP、ALB、ALT on day21and TP、ALB、 ALT、AST、y-GT on day42between treatments (P>0.05).When broilers were fed diets with contaminated corn, the activity of GSH-Px on day21and the content of hepatic protein on day21and42in livers significantly decreased (P＜0.05), the activities of GR, SOD. GST and the concentration of MDA significantly increased (P<0.05).Broilers fed diets with naturally contaminated corn could induce pathological lesions and ultrastructural changes of livers, and as the ratio of contaminated corn increased, the extent of pathological lesions and the apoptosis rate of livers increased (P<0.05). The average scores of pathological lesions in control,25%,50%,75%and100%contaminated groups were0,0.67,0.83,1.83,3.67on day21, and0,0,0.17,0.33,0.5on day42, respectively.The levels of aflatoxin residue in livers from50%and100%contaminated groups were0.049and0.137μg/kg for AFB1,0.033and0.051μg/kg for AFM1, respectively, which were higher than AFB1residues in breast muscles (0.015and0.016μg/kg).These results indicated that when the inclusion of naturally contaminated corn exceeded50%in the starter diets and reached100%in the grower diets (36.9-82.4μg/kg AFB1from day1to21;134μg/kg AFB1from day22to42), it would negatively affect poultry health including poor performance, intestinal morphology change, pathological lesions of hepatic structure and function. Furthermore, the aflatoxin residues would be detected in liver and breast muscle of broilers.更多还原