An experiment was concucted to study the effects of adding graded levels of
betaine either alone or in combination with either enzymes preparation (EP)
containing ec-ernylase. xylanase and protease or Ascorbic acid (Vitamin C) on
productive performance and carcass characteristics of broiler chicks raised under high
ambient temperatures. A number of 144 day- old "Hubbard" broiler chicks were
assigned to 6 treatment groups of 24 chicks in individual cages where every chick
represented one replicate. The six experimental diets were: control treatment diet (T ,)
which was formulated to be without supplemental betaine. treatments diets (Ta) , (T3)
and (T4) which were similar to control diet (TI) but they were supplemented with
commercial betaine (91%) at inclusion rate of 500.1000 or 1500 ppm, respectively.
While, (Ts) and (Ts) diets were supplemented with 1000 ppm betaine (91%) combined
with 1 kg of EPfron or 200 ppm Vitamin C (1 kg 20% I Ton). Chicks of all treatments had similar growth performance at the end of starter
period (18 days of age). Thenafter, body weight of chicks at the end of growing period
(40 days of age) increased by increasing dietary betaine level (T2, T3, T., To, and Ts),
with priority for Ts and Ts (P(T1). While. the dietary treatments
did not show any significant effect on feed consumption and feed conversion ratio at
this age. At 49 days of age, the best results in regard to the productive performance,
carcass characteristics and economic efficiency were recorded by using either 1500
ppm added betaine only (T.) or 1000 ppm betaine combined with EP or VItamin C (T 5
Or T G. respectively). It could be concluded that the usa of betaine supplemented diets (graded levels
alone or in combination with either EP or Vit.C) may be considered as a suitable mean
to overcome the depressing effect of heat stress. The dietary betaine level of 1500
ppm or 1000 ppm combined with either 1 kg of EP fron feed or 200 ppm Vit.C would
be preferable lor chicks kept at hot conditions, with respect to growth performance
and economic efficiency.