| In recent years,there are many studies give attention to the toxic effects of florfenicol on pigs,sheep,horses and other livestock,but few reports on the toxic effects of florfenicol on broilers.At present,florfenicol is widely used in broilers breeding,and even exists abuse phenomenon,which not only leads to drug residues in the body of broilers,but also damages the body of broilers,resulting in multiple diseases.In order to investigate the damage of florfenicol on liver and immune function of Broilers and the alleviating effect of Salvia miltiorrhiza polysaccharide,the following experiments were carried out.1.To study the effects of early administration of florfenicol(FFC)on the growth and liver function of broilers.Three hundred and sixty 1-day-old AA broilers were randomly divided into 6 groups,60 in each group.Except for the control group,the other five groups were given different doses of FFC(0.15 g/L,0.3 g/L,0.6 g/L,1.2 g/L,1.8 g/L)in drinking water for 5 days,then returned to normal feeding.At the age of d6,d21,and d42,twenty broilers in each group were randomly selected for blood collection,and the broilers were killed to take liver samples for detection of related indicators.The results showed that:compared with the control group,At the age of d6,d21,and d42,the weight gain of broilers in each experimental group were significantly decreased(P<0.05).At the age of d6 and d21,the experimental group compared with the control group,the activities of ALT and AST were significantly increased(P<0.05),and the contents of TP and ALB were significantly decreased(P<0.05);At the age of d42,there was no significant difference in the activities of AST and ALT among each group(P>0.05);When FFC dosage was more than 0.6 g/L,the contents of TP and ALB in serum of broilers were significantly decreased(P<0.05).At the age of 6d and 21d,the experimental group compared with the control group,the content of MDA in the serum of broilers were significantly increased(P<0.05).At the age of d42,1.2g/L and 1.8g/L FFC could still significantly increase the content of MDA in the serum of broilers(P<0.05).the experimental group compared with the control group,at age of d6,the contents of GSH and CAT in serum were significantly reduced(P<0.05);At age of 21d and 42d,only FFC higher than 0.6 g/L,the contents of GSH and CAT in serum of broilers were significantly reduced(P<0.05).At age of 6d and 21d,the activities of CYP1A1 and CYP2H1 and their mRNA transcription were significantly inhibited(P<0.05);At age of 42d,FFC higher than 0.3g/L still significantly inhibited the transcription level of CYP1A1 mRNA in liver tissue of broilers(P<0.05).At age of 6d,the mRNA transcription and protein expression of Nrf2,HO-1,and NQO-1 were significantly inhibited in all FFC group(P<0.05);the mRNA transcription of Nrf2,HO-1,and NQO-1 were significantly inhibited in 1.2g/Land 1.8g/L FFC group at age of d21 and d42(P<0.05).At age of 6d,the apoptosis rate and the expression of Caspase-3 and caspase-6 mRNA and protein were significantly increased(P<0.05);At age of d21 and d42,there was no significant difference in the mRNA transcription and protein expression of Caspase-3 and caspase-6 between FFC group and control group(P>0.05).Conclusion:0.15 g/L FFC can damage the growth,hematopoiesis,and liver function of young broilers;However,with the growth of broilers,the clinically recommended dose(0.15 g/L)of FFC could alleviate the damage of growth,hematopoiesis and liver function;In addition,FFC may damage the liver by inhibiting the protein activity of the Nrf2 are pathway and increasing liver oxidative stress to mediate liver injury and affect liver function.2.In order to explore the alleviating effect of Salvia miltiorrhiza polysaccharides(SMPs)on liver injury induced by FFC in broilers.Three hundred and sixty 1-day-old broilers were randomly divided into 6 groups:control group,SMPs control group,FFC control group and low,medium and high dose of SMPs experimental groups,with 60 in each group.FFC control group and SMPs experimental group were treated with 0.15g/L FFC for 5 consecutive days.The low,medium and high of SMPs groups were given 1.25g/L,2.5g/L and 5g/L SMPs respectively for drinking water.At the age of 6d,21 d and 42d,20 broilers in each group were randomly selected to collect blood from the inferior wing vein,and the broilers were killed to take liver samples to detect the related indicators.The results showed that:at age of 6d,21d and 42d,compared with control group,the weight gain,the expression of CYP1A1 in liver tissue,the transcription levels of Nrf2 and GSTT1 mRNA in liver tissue of broilers were significantly decrease in FFC group(P<0.05),the liver index and the content of MDA in liver tissue were significantly increased in FFC group(P<0.05);compared with FFC group,the weight gain,the transcription levels of Nrf2 and GSTT1 mRNA in liver tissue were significantly increased in SMPs group(P<0.05),the liver index and MDA content in liver tissue were significantly reduce in SMPs group(P<0.05);At the age of 6d and 21d,compared with the control group,the content of AST and ALT in serum,the apoptosis rate of liver cells,the mRNA transcription and protein expression of apoptosis related factors P53,CytC and caspase-3 were significantly increased in FFC group(P<0.05);the content of TP in serum,the content of SOD and CAT in liver tissue and the expression of CYP1A1,CYP2H1,UGT2A1,HO-1 and NQO-1 mRNA or protein expression in liver tissue were significantly reduced in FFC group(P<0.05).At the age of d42,there was no difference between FFC group and control group(P>0.05).At age of 6d and d21,compared with FFC group,in SMPs group,the content of AST and ALT in serum were significantly reduced(P<0.05),the apoptosis rate of liver cells and the expression of P53,CytC and Caspase-3 were significantly inhibited(P<0.05),the content of TP in serum,the content of SOD and CAT in liver tissue,and the content of CYP1A1,CYP2H1,UGT2A1,HO-1 and NQO-1 mRNA or protein expression in liver tissue were significantly increase(P<0.05).At the age of d42,there was no difference between FFC group and SMPs group(P>0.05).In addition,there was no significant difference between SMPs control group and control group in each period(P>0.05).Conclusion:SMPs can inhibit hepatocyte oxidative stress by regulating Nrf2 pathway related proteins,thereby reducing hepatocyte apoptosis and protecting liver injury induced by FFC in broilers,and 5 g/L SMPs has optimal effect.3.In order to explore the effect of Salvia miltiorrhiza polysaccharides(SMPs)on immune function damage of broilers caused by florfenicol(FFC).nine hundred chickens were divided into 6 groups.Twenty broilers were randomly selected from age of 6 d,7 d,14 d,21 d,28 d,35d and 42 d,and 20 broilers were randomly selected from age of 6 d,21 d and 42 d,respectively.The results showed that:compared with the control group,at the age of 6 d;the amounts of Mon and WBC in whole blood,the contents of IgM,IgG,IL-2,IL-4 and IFN-γ in serum of broilers were significantly decreased in FFC group(P<0.05);At age of d21 and d42,there was no significant difference between FFC group and control group(P>0.05).At the age of 6 d,compared with FFC group,the amounts of Mon and WBC in whole blood of broilers and the contents of IgM,IgG,IL-2,IL-4 and IFN-γ in serum of broilers were significantly increased in 2.5g/L and 5g/L SMPs group(P<0.05).At age of 21 d and 42d,compared with control group and FFC group,the number of white blood cells,the titers of antibodies against Newcastle disease(ND)and avian influenza(AI)and the contents of immunoglobulin(IGA,IgG and IgM)and cytokines(IL-2,IL-4 and IFN-y)in serum were significantly increased in 2.5g/L and 5g/L SMPs group(P<0.05).the lymphocyte transformation rate of broilers in 5g/L SMPs group(P<0.05).Conclusion:FFC can damage the immune function of young broilers,and with the age increase of broilers,the damage of FFC on the immune function of broilers can be recovered;SMPs can effectively alleviate the damage of FFC-induced the immune function of broilers,especially the dose of 5g/L SMPs can significantly improve the immune function of broilers. |
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