Effects Of Corn Naturally Contaminated With Mycotoxin On Performance, Health And Aflatoxin Residues In Broilers

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.