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An experiment with 540 one-day-old broilers (CobbS00) was conducted to investigate the effects of different immune stress on growth performance, digestive enzyme activity and expression of small intestinal nutrient transporter gene on broilers.The chickens were divided into 5 groups with 9 replicates per group and 12 birds per replicate (group 1, control without vaccines, CK; 2, simplified vaccines, SV; 3, conventional vaccines,CV; 4, lipopolysaccharide injected on the basis of conventional immunization, LPS ; 5, cyclophosphamide injected on the basis of conventional immunization, CYP).Performance parameters and small intestinal weight was measured on d 21 and d 42.The results showed that body weight gain (BWG) and feed intake (FI) decreased significantly when birds treated with LPS and CYP (P < 0.05).Birds in SV had higher duodenal relative weight index than those of LPS and CPY on d 21 (P < 0.05).Compared with CK, LPS and CYP injection significantly increased the small intestinal enzyme activities of broilers (P < 0.05).LPS and CYP treatment also increased relative abundance of sodium glucose co-transporter 1, Calcium-binding protein-D28k and L-fatty acid-binding proteins mRNA of broilers (P < 0.05) , whereas there was no significantly difference between SV and CV (P >0.05).Results of the present study demonstrated that CK or SV treatment could reach the same growth performance, small intestine enzyme activity and relative expression of nutrient transporter mRNA as broilers with CV in the conditions of controlling rational feeding environment.LPS and CPY treatment increased small intestine enzyme activity and nutrient transporter mRNA, result of immunity stress caused energy consumption to synthesis of inflammatory factors, lower FI and BWG, finally inhibit the growth of broiler chickens.