Effects Of Different Levels Of Dietary Tin On Growth Performance And Health In Broilers

The trial was conducted to study the effect of different tin levels on the growth performance and health of broilers.210 7-day-old healthy Avian broilers were randomly assigned to 7 groups with 5 replicates of 6 each according to initial body weight. The trial was divided into two phases(2-4 weeks,5-7 weeks). The control group was provided with basal diet. Treatment groupsⅠ,Ⅲ,Ⅲ,Ⅳ,ⅤandⅥwere fed basal diet containing 120 mg/kg,240 mg/kg,360 mg/kg,480 mg/kg,600 mg/kg and 720 mg/kg SnCl2, respectively. Chickens were monitored daily and then daily feed intake and body weight were recorded on the first day and weekly. At the end of the third and the sixth week of experiment,2 chickens were selected randomly from each replicate, and jugular bloodletting then slaughtered. The effect of Sn on the growth performance, slaughter performance, antioxidative indexes, liver lesion and tissue residues of broilers were determined. The results showed as follows:The growth performance:The ADFI of all groups were lower than the control. Treatment groupsⅥsignificantly decreased ADFI by 12.06% compared with the control during the first 3-week period (P<0.05). Treatment groupsⅣ,ⅤandⅥsignificantly decreased ADG and ADFI, increased F/G compared with the control during the last 3-week period (P＜0.05).The slaughter performance:During the whole experiment, feeding diets containing Sn compared with the control, the dressing percentage, eviscerated carcass rate and semi-eviscerated carcass rate had no significant differences (P>0.05).The antioxidative function:During first 3-week period, feeding diets containing Sn compared with the control, SOD and GSH-Px activities in liver were decreased. Treatment groupsⅤandⅥsignificantly decreased the activity of GSH-Px in liver (P＜0.05). Treatment groupsⅣ,ⅤandⅥsignificantly decreased the activity of SOD in liver (P＜0.05). All treatment groups compared with the control, the concentrations of MDA in liver increased. Treatment groupsⅣ,ⅤandⅥsignificantly increased the concentrations of MDA in liver (P＜0.05). During last 3-week period, all treatment groups decreased the SOD and GSH-Px activities in liver compared with the control. Treatment groupsⅣ,ⅤandⅥsignificantly decreased the activities of GSH-Px and SOD in liver (P＜0.05). Feeding diets containing Sn compared with control, the concentrations of MDA in liver were increased. Treatment groupsⅥsignificantly increased the concentrations of MDA in liver (P＜0.05). The antioxidative function was harmed by adding tin in dietary. Liver damage:All treatment groups compared with control group, ALT and LDH activity had no significant differences in blood serum (P>0.05). During first 3-week period, all treatment groups compared with the control, AST and AKP activities were significantly increased (P<0.05). During last 3-week period, AKP activities of all treatment groups were higher than the control, and treatment groupsⅣ,ⅤandⅥsignificantly increased (P＜0.05). The liver was damaged by adding tin in dietary.Residual tin in tissue organs:All treatment groups compared with the control, breast muscle, leg muscle, muscular stomach, glandular stomach, liver, kidney, heart, tibia and feather tin contents were significantly increased (P＜0.05). There were significant differences among all treatment groups (P<0.05). With the concentration of Sn increasing and the time going, the contents of tin in tissue organs were increased. Throughout the whole experiment, tin in breast muscle was the lowest, and in tibia was the highest. These results showed the growth performance, the antioxidative function, the liver function and health were decreased by adding 480 mg/kg or more SnCl2. The contents of tin in different tissues were significantly increased (P＜0.05) with the increasing contents of tin in dietary compared with the control. Tin distributed mainly to bone and feather.