| The study was conducted to examine the effect of dietary supplement phytosterols (PS) on the performance and its action mechanisms of broilers. The paper included three trials:In experiment one, a total of 756 0-day-old AA commercial broilers were randomly allotted into six treatments with six duplicates per treatment. Treatment 1 was control group fed with basal diet, treatment 2 to 6 added 5mg/kg, 10mg/kg, 20mg/kg, 40mg/kg and 80mg/kg PS in their basal diets, respectively. The effects of PS on performance of 21-day-old and 42-day-old, cholesterol and proteins levels in serum and antioxidant capacity of 42-day-old broilers were investigated in the experiment. The results indicated: (T)40mg/kg treatment improved the average weight gain (P<0.05) and body weight (p<0.01) of 21-day broilers significantly, it also increased 21~42-day and 0~42-day weight gains and 42-day body weight (P>0.05). (2)20mg/kg treatment decreased the levels of TC (P<0.05) and LDL-C (P<0.01) in serum significantly. 10mg/kg, 40mg/kg and 80mg/kg treatments decreased LDL-C level in serum significantly (P<0.05), increased HDL-C level too (p>0.05), but had no significant effect on TG level in serum (P>0.05). (3)40mg/kg treatment increased TP and A/G values, decreased globulin value in serum (P>0.05), and improved albumin value significantly (P<0.05). (D80mg/kg treatment significantly improved the activities of T-SOD in broilers serum of 21-day and 42-day, 20mg/kg, 40mg/kg and 80mg/kg treatments increased the activity of GSH-Px in serum (P>0.05).In experiment two, a total of 305 0-day-old AA commercial broilers were randomly allotted into three treatments with five duplicates per treatment, Treatment 1 was control group fed with basal diet, treatments 2 and 3 added 20mg/kg and 40mg/kg PS in their basal diets, respectively. The experiment was carried out in summer to study the effects of PS on performance of broilers on 21-day and 42-day and the biochemistry indices of tissues on 42-day. At 42 days, one broiler was slaughtered in each duplicate of all treatments to investigate effects of PS on slaughter performance of broilers. The results showed: Compared with control, â‘ In the case of heat stress in summer, 20mg/kg and 40mg/kgtreatments increased FCR of broilers (P>0.05), 20mg/kg treatment significantly improved FCR of 0~42-day (P<0.05). 40mg/kg treatment got the highest weight gain in all treatments. â‘¡20mg/kg and 40mg/kg treatments decreased abdominal fat rate, increase breast muscle rate, leg rate and wing rate (P>0.05). 20mg/kg treatment increased breast muscle rate significantly (P<0.05). 20mg/kg and 40mg/kg treatments decreased slaughter rate, half evisceration rate and evisceration rate (p>0.05). â‘¢20mg/kg and 40mg/kg treatments significantly decreased cholesterol level in liver of broilers (P<0.01), the cholesterol levels in breast muscle and leg muscle were decreased (P>0.05), the total proteins levels in liver, breast muscle and leg muscle were improved (P>0.05), crude fat in liver was decreased and in breast and leg muscle was increased (P>0.05).40mg/kg PS treatment showed the best performance in experiment one and two. In experiment three, 504 0-day-old AA commercial broilers were randomly allotted into four treatments with six duplicates per treatment. The crude protein levels in feed of treatments 1 and 3 were 19% in starter phase and 17% in finishing phase, respectively, and in treatments 2 and 4 were 21% in starter phase and 19% in finishing phase, respectively. 40mg/kg PS were added into feed of treatments 2 and 4 to investigate the effect of PS on performance of broilers. At 40 days, one broiler was selected out from each duplicate of all treatments to investigate effects of PS on nutrient metabolism of broilers. The results showed as followings: the performance and nutrient metabolism in treatments 2 and 4 were better than treatments 1 and 3. When the crude protein was lower, 40mg/kg PS treatment increased performance and nutrient metabolism of broilers (P>0.05). When the crude protein was higher, 40mg/kg PS treatment decreased perfor...
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