| Two experiments were conducted to determine the impact of maize naturally contaminated with mycotoxins on antioxidative capability as well as the protective effects of selenium and vitamin E on rats that consumed maize naturally contaminated with mycotoixins.Exp.1 Impact of Maize Naturally Contaminated with Mycotoxins on Antioxidative Capability in RatsThis study determined the impact of maize naturally contaminated with mycotoxins on antioxidative capability in rats.48 Wistar female rats were randomly divided into three groups:control group was given the basic diet with normal maize;low mycotoxin group (LM) was given the diet in which normal maize was 50%replaced by mycotoxin-contaminated maize;high mycotoxin group(HM) was given the diet in which normal maize was 100%replaced by mycotoxin-contaminated maize.The trial lasted for 4 weeks.All rats were provided with water and feed ad libitum.At the end of the experiment, all the rats were anesthetized.Blood samples were then collected from heart.Serum was prepared to measure activities of superoxide dismutase(SOD),gluthathione peroxidase (GPX),glutamate-pyruvate transaminase(GPT),glutamic-oxalacetic transaminase(GOT), lactate dehydrogenase(LDH),and alkaline phosphatase(ALP) and contents of malondialdehyde(MDA).Rats were anatomized after blood collection,the weight of liver, kidney and spleen were determined to calculate the internal organ indexs.Average daily gain(ADG) and average daily feed intake(ADFI) of rats at 0～14d,15～28d,and 0～28d were measured synchronously.The results showed that there was no significant difference in ADG(0～14d,15～28d,0～28d),ADFI(0～14d),and FCR(0～14d,15～28d,0～28d) among groups.The ADFI of LM group,HM group at 15～28d and overall ADFI of HM were significantly higher than control(p＜0.05).No significant differences were observed in liver, kidney,or spleen index.Compared with control group,activities of SOD in both LM group and HM group were decreased significantly(p＜0.05).Furthermore,activity of GPX in HM group was depressed significantly compared with control(p＜0.05).There was no significant difference in activity of GPT among groups.The activities of GOT in both LM group and HM group were significantly lower than those in control(p＜0.05),whereas activities of ALP and LDH in LM and HM group were significantly higher than those in control(p＜0.05).It was suggested that the maize naturally contaminated with mycotoxins inhibited the antioxidative capability and induced liver function damage in rats,and the extent of this impact depended on the substitutable proportion of mycotoxin-contaminated maize in diets.Exp.2 Protective Effects of Antioxidants on Rats Consuming Maize Naturally Contaminated with MycotoxinsThis study determined the protective effect of antioxidants selenium and vitamin E on rats that consumed maize naturally contaminated with mycotoxins.Thirty-two Wistar female rats were randomly divided into four groups:control group was given the basic diet with normal maize;mycotoxin-contaminated maize group(MCM) was given the diet in which normal maize was replaced by mycotoxin-contaminated maize;selenium group (YSe) and vitamin E group(VE) was respectively fed mycotoxin-contaminated diet supplemented with 0.4 mg/kg selenium from yeast or 100 mg/kg vitamin E.The trial lasted for 4 weeks.All rats were housed individually in stainless-steel cages and were provided with water and feed ad libitum.At the end of the experiment,all the rats were anesthetized. Blood samples were then collected from heart.Serum was prepared to measure total antioxidative capacity(T-AOC),activities of GPX,SOD,GPT,GOT,LDH,ALP and contents of MDA,Nitric Oxide(NO).Rats were anatomized after blood collection,the weight of liver,kidney and spleen were determined to calculate the internal organ indexs. Body weight gain(BWG) and average daily feed intake(ADFI) of rats were measured synchronously.The results showed that there was no significant difference in BWG and ADFI among groups.The rats consumed maize naturally contaminated with mycotoxins trended to decrease BWG and ADFI compared with control group,whereas supplementation of selenium and/or vitamin E improved the growth performance in rats consumed mycotoxin-contaminated maize.No significant differences were observed in kidney index or spleen index.The liver index in MCM group was significantly higher than that in control,whereas those in YSe group and VE group trended to be reduced. Compared with control group,activities of SOD,GPX,and T-AOC were decreased significantly in MCM group(p＜0.05).The activities of SOD,GPX,and T-AOC in YSe or VE group were increased significantly compared with MCM group(p＜0.05).The content of NO in MCM group was significantly higher than other groups(p＜0.05),whereas that in VE group was also much higher than that in control group(p＜0.05).The activities of GPT, GOT,LDH and ALP in MCM group were significantly higher than those in control group (p＜0.05).The activities of GPT,GOT,LDH and ALP in the YSe and/or VE group were significantly lower than those in MCM group(p＜0.05).It was proposed that selenium and vitamin E were able to alleviate oxidative injury and liver function damage due to consumption of maize naturally contaminated with mycotoxins.In summary,the maize naturally contaminated with mycotoxins inhibited the antioxidative capability and induced liver function damage in rats,and this impact depended on the substitutable proportion of mycotoxin-contaminated maize in diets.The supplementation of 0.4 mg/kg selenium or 100 mg/kg vitamin E in mycotoxin-contaminated diet was able to alleviate oxidative injury and liver function damage due to the consumption of mycotoxin-contaminated maize.
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