An experiment was conducted to study the performance, some physiological
and immunological responses to heat stress in broiler chickens fed on diets containing"
1% betaine andlor 0.5% sodium bicarbonate. A total number of 180 broiler chickens at
one-day of age were used. Birds were divided to 4 equal groups that were randomly
allotted to one of the following four treatments 1) basel diet supplemented with 0.5%
sodium bicarbonate, 2) basel diet supplemented with 0.5% sodium bicarbonate and
1% betaine, 3) basel diet supplemented with 1% betaine, and 4) basel diet without
any supplements served as control. The birds were subjected to high ambient
temperature (40°C±1°C) for 6 hrs per day from the 2Slti day up to the end of the
experimental period (49 days of age). The results could be summarized as follows: .Significant (P were detected in the birds fed diet supplemented with 1 % betaine compared with
the control group . A significant (P fed diet supplemented with 0.5% sodium bicarbcnate compared with the control
group . A significant decrease (P<0.01) in water consurnptlon was observed in the
experimental grcup fed diel supplemented with 1 % betaine compared with the
control qroup. ,Significant decreases (P for birds fed diet supplemented with 0.5% sodium bicarbonate and 1 % betaine
and the birds fed diet supplemented with 1% betaine compared with the control
group. ·Significant increase (P<0.01 and P<0.05) in bursa of fabricius and adrenal gland
weight index was observed in all experimental groups fed supplemental diets
compared with the control group . Significant increases (P were observed in the group of birds fed diet supplemented with 0.5% sodium
bicarbonate and 1% betaine compared with the control group . Significant decreases (P<0.05 and P total protein, albumin and globulin levels were observed in the experimental
groups fed diets supplemented with 0.5% sodium bicarbonate and 1% betaine
and the diet supplemented with 1 % betaine compared with the control group.