| 300 two-week-old Avian female broilers were randomly divided into 5 groups. During the first stage, all the groups received a basal diet formulated according to the Feeding Standard of female broiler. The two control groupsf I . II) received a basal diet formulated according to the Feeding Standard of female broiler. The other three experimental groups (III,IV and V ) were given the basal diets plus 200ppm Ascorbic Acid, 0.5% sodium bicarbonate and 1% ammonium chloride, 250ppm vitamin E respectively. The first group named normal-temperature-control group( I ) were reared under 24 癈 to 27癈. the second group named high-temperature-control group( II ) and the other three experimental groups(III.IV and V) named additive trial groups were reared at 30~35癈 in the second stage and 32.5~~35癈 in the third stage. The relative humidity of experiment chamber was maintained between 70% and 85%. The trial was conducted to study the effect of heat stress and different addictives on performance blood biochemical indices, rectal temperature, the qualities of chicken meat. The results as follow:(1) Our studies showed that daily feed intake, average weight gain and feed efficiency significantly decreased in 300 Avian female broilers exposed to 30-35 癈 environmental temperature at 14 days old of age. Daily feed intake, average weight gain and feed conversion ratio decreased by 9.65%(p>0.05), 13.22%(p<0.05). 3.97%(p>0.05)respectively in 14-22 days old female broilers. Daily feed intake, average weight gain and feed conversion ratio decreased by 10.54%(p<0.05), 19.37%(p<0.05), 9.78%(p<0.05) in 23-31 days old female broilers. For the whole second stage, daily feed intake, average weight gain and feed conversion ratio decreased by 10.18%(p>0.05). 16.67%(p<0.05),9.74%(p>0.05) respectively.(2) A total of 270 Avian female broilers were exposed to high environmental temperature (32.5-35癈) again, studies showed that heat stress could decrease dailyfeed intake, average weight gain and feed conversion ratio by 22.02% (p<0.05). 39.!5%(p<0.05). 22.05% (p<0.051 respectively. So the experiment showed that the older female broilers were, the less growth production they had.(3) The results showed that some anti-heat stress additives in feed significantly prevented heat stress. Additive in feed at the level of 0.5%NaHCO.i and T/oNHjCl gave the best results. It increased average weight gain by 6.43%(p<0.05) for the 14-31 days old female broilers and increased the body weight and feed conversion ratio by 27.54%(p<0.05) and 20.1 9%(p<0.05). As far as additive III in feed at the level of 200ppm vitamin C concerned, it could increase average weight gain by 4.24%(p<0.05) for the 14-31 days old female broilers.(4) Avian female broilers at 14 day old of age exposed to 30-35癈 environmental temperature, studies showed that heat stress could significantly increase the concentration of glucose and corticosteroid. Heat stress decreased the concentration of serum ALP, T3 and T4, but serum corticosteroid declined in the third stage. The effect of heat stress on inorganic ions concentration in serum was very intricate.(5) Heat stress also made immune organs atrophy such as bursa, spleen, thymus. and their absolute weight decrease significantly, and their relative weight decrease at the same time. However, anti-heat stress additives had no good significant effects on immune organs. On the contrary, additives made them atrophy.(6) Heat stress affected qualities of chicken meat; it increased abdominal fat ratio, incidence of pale, soft, and exudative broiler meat (PSE meat). But vitamin E improved the qualities of chicken meat. Three kinds of additives decreased the abdominal fat 'body weight ratio significantly.(7) The rectal temperature of female broilers changed with high ambient temperature significantly in the same day. Between 27~33癈and 28~34癈...
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