A total of 990 fertile eggs (Commercial broiler Arbor Acres type) were
used to study the effect of amino acid (AA.) injection into hatching eggs on the
productivity of producing chicks. The eggs were taken from 52-56 weeks old hens and the average egg weight
was 65 gm average. The eggs were assigned randomly to six equal groups, 165 eggs
each. The first group was used as control (without any treatment), the second group
was holed only (no injection), the third group was injected with 0.05 ml distilled water,
the fourth group was injected with 0.05 ml distilled water contains 4.2 mg Arginine, the
fifth group was injected with 0.05 ml distilled water contains 3.35 mg lysine and the
sixth group was injected with 0.05 ml distilled water contains 1.5 mg histidine. The injection of amino acids was completed with an automatic egg injection
machine (INOVOJECT) at the 7^th day of incubation time (embryonic development). The obtained results were as following: 1)  Amino acids injection at yth day of incubation decreased hatchability. 2)     The highest mortality rate was during the second week of incubation for injected
groups comparing with other incubation periods. 3) No significant (P<0.05) differences were observed between treatments and controls
at hatch, this due to selection the treated eggs with the same weight. At first week,
control 1 (without treatment) has higher body weight than other groups, also,
lysine and histidine treatments have decreased body weight (P ~0.05) than other
treatment (arginine) and controls. Result showed the same trend during the
second week of age. 4) During the s", 6^th and 7^th weeks of age, there was no significant (P~0.05) difference
in body weight between all of treatments and controls. 5)     No significant differences (P~O.05) in plasma constituents (glucose, total lipids,
high-density lipoproteins (HDL), GOT, GPT and T 3) between all experimental
groups. 6) Lysine and histidine amino acid increased plasma total protein and albumin but this
increase was not significant. 7)     Relative weights of lymphoid organs (% of body weight) at the 3'd and s" weeks of
age had no significant (p~0.05) differences between all treatments and control.
This may demonstrate that amino acids injection had no direct effects on relative
weights of lymphoid organs between treatments and controls.