| The main objective of this thesis is to study the effects of heat stress on the performance, carcass characteristics, meat visual quality, serum biochemical parameters, MDA concentration of tissues and HSP72mRNA of liver during the age of 28-50 days healthy Arbor Acre(AA) broilers. The results showed that: heat stress decreased the broiler's performance and had harmful effect to the meat quality.(1) Two hundred and seventy 28-day-old AA broilers were equally divided into 3 groups to study the effect of high temperature on its performance, blood metabolic product. There were 6 replicates in each group and 15 chickens in each replication. Pair test design was adopted to test the effect of ambient temperature on broilers.One group broilers(34AL) were in diurnally high temperature(ET28.8 # -36.5 # -28.8 # ), another group broilers(22AL) fed ad libitum in neutral thermal environment (ET21.2#), the other group broilers(22PF) raised in neutral thermal(ET21.2#) but gave feed consumed by high temperature just before one day. Each replication were weighed at 0, 7, 14, 21 days and collected blood to measure the content of Glu, UA, TG, TP, ALB and GLOB. The carcass character and meat quality were measured at 21-day. The results showed: ?Heat stress decreased broilers' feed intake, growth rate and feed conversion, while these effect were not independent on the decrease of the feed intake. Compared with the 22AL group and 22PF group, ADG of the high temperature group with 3 weeks decreased 39.05% and 14.22%(P<0.01) respectively, feed conversion increased 25.64% and 15.29% (P<0.01) respectively. Comparing to the neutral group, feed intake of the high temperature decreased 24.24%( P<0.01). (2) High temperature increased the serum Glu content significantly but subsequently decreased it. With the long time under the high temperature, the serum TG had the downward trend. The TG content of the high temperature of 3-week decreased significantly (P<0.05), but the serum TP, ALB and GLOB had no obvious change (P>.05). Compared with 22AL group, the UA content increased with the long time of high temperature, but there had no significant difference during the three weeks. Compared with 22AL but feed limited group, the serum indicator all increased obviously after the three weeks high temperature. (3) It was found that compared to 22AL group, high temperature increased the broiler chicks' slaughter weight rate, full net carcass rate, semi net carcass rate, leg muscle rate and abdominal fat rate significantly (P<0.01). Compared with the22PF group, the high temperature group had higher full net carcass rate (P<0.05), semi net carcass rate (P<0.01), leg muscle rate and abdominal fat rate (P<0.01), while the other indicator had no significant difference(P>0.05). (4) High temperature had obvious influence on some muscular sensation indicator. Compared with 22 AL group, high ambient temperature enhanced significantly the value of L*, drip loss and shear value of breast and thigh meat (P<0.01), while a value of leg meat decreased significantly (P<0.01), but breast a value, breast and leg b value, the Ph value of 15min and 24h after slaughter were not significant affected (P>0.05). The others indicator had not significant difference.(2) Two hundred and seventy 28-day-old AA broilers were equally divided into 3 groups, 6 replicates in each group and 15 chickens in each replicate to study the effect of high temperature to broilers' serum enzyme, lipid peroxidation and the active change of HSP72mRNA. Pair test design was adopted to test the effect of ambient temperature on broilers. One group broilers(36AL) were in diurnally high temperature(ET28.8#~36.5# -28.8 #), another group broilers(22AL) fed ad libitum in neutral thermal environment (ET 21.2#), the other group broilers(22PF) raised in neutral thermal(ET21.2#) but gave feed consumed by high temperature just before one day. Each group slaughtered 6 broilers at 2, 5, 8, 12, 15, 22 day, and collected blood to measure the activity of AKP, CK, LDH and the content of MDA. MDA content of the liv...
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