The Effect of Injecting Hatching Eggs with Gamma-Aminobutyric Acid (GABA) on Hatching Characteristics and Some Blood and Immunity Traits of Hatched Chicks

Abstract

This study included a hatching experiment to investigate the effect of early  feeding using different levels of gamma-aminobutyric acid (GABA) solution  on hatchability and characteristics of hatched broiler chicks. Six hundred  hatchable eggs from a single flock of Ross 308 broiler breeders, 46 weeks old,  were used. The eggs, weighing 64 g each, had been stored for two days and  were incubated in a setter at 99.8°F (37.8°C) and 60% relative humidity. The  eggs were turned automatically once every hour. On day 18 of incubation,  before transferring the eggs to the hatcher, they were candled in a sterile, dark  room (egg transfer room) at 25°C and 55% relative humidity. Four hundred  and eighty fertilized eggs were randomly divided into four treatments, with  three replicates per treatment. In a treatment of 40 eggs per replicate, the eggs  were incubated in the hatcher at 98.6°F (37°C) and 70% relative humidity  until hatching. The treatments were distributed as follows: T1 (negative control): Hatching eggs without injection T2 (carrier control): Hatching eggs injected with 0.2 ml/egg of N.S. T3: Hatching eggs injected with 0.2 ml/egg of 10% gamma-aminobutyric  acid solution. T4: Hatching eggs injected with 0.2 ml/egg of 15% gamma-aminobutyric  acid solution. The hatching rates observed showed that the injection treatments T3 and  T4 were significantly superior to the negative control and carrier treatments  T1 and T2 in terms of embryonic mortality. The mortality rate was lower  in T3 and T4 (0.83 and 1.12, respectively) compared to 2.50 for the control  treatment T1. There was also a significant advantage (P ≤ 0.05) in both the  overall hatching rate and the hatching rate of fertilized eggs for the injection  treatments T3 and T4. These treatments significantly outperformed the  negative control and carrier treatments T1 and T2, recording 96.66% and  94.76% for the overall hatching rate and 96.66% and 94.76% for the hatching  rate of fertilized eggs, respectively, compared to 93.33% and 93.33% for the  control and carrier treatments T1 and T2, respectively. In  terms of hatchability and live pecking percentage, the third  and fourth injection treatments (T3 and T4) significantly  outperformed the other treatments, recording 95.83% and  92.83%, respectively, compared to 91.66% for the control  treatment (T1). The same table shows no significant  differences between the treatments in the percentage of  dead pecking chicks. Regarding vital organs, a significant  decrease in the percentage of residual yolk was observed in  the injection treatments (T3 and T4) at 3.00% and 3.34%,  compared to 3.76% for the control treatment (T1). No  significant differences were found between the treatments  in the percentages of heart, liver, pancreas, and spleen.  Regarding immunoglobulin (Ig) characteristics, there was a  significant improvement, with the third and fourth injection  treatments (T3 and T4) outperforming the other treatments.  These treatments recorded Ig levels of 45.33 and 45.33 mg/ dl, respectively, compared to 39.33 mg/dl for the control  treatment (T1). The two treatments also recorded Ig levels  of 1044.33 and 1048.33 mg/dL, respectively, compared to  1004.00 mg/dl for the control treatment (T1). Regarding  vital organ measurements, an increase in the fetus’s ability  to utilize residual yolk was observed. A significant decrease  in the relative weight of residual yolk was noted in the early  feeding treatments (T3 and T4), reaching 3.00% and 3.34%,  respectively. Compared to the negative control and carrier  treatments T1 and T2, which reached 3.76% and 3.62%,  respectively, the same table shows no significant differences  between the experimental treatments in the percentage  weight of the heart, liver, spleen, and pancreas of the chicks  at hatching. Regarding biochemical characteristics, a  significant decrease was observed in the T3 and T4 injection  treatments in both aspartate aminotransferase (AST) and  alanine aminotransferase (ALT) levels, which were recorded  at 141.46 and 142.36 U/L, respectively, compared to 180.33  U/L for the control treatment T1. For ALT, the T3 and T4  injection treatments recorded 3.22 and 3.31 U/L, respectively,  compared to 3.86 U/L for the control treatment T1. No  significant differences were observed between the treatments  in the percentage of albumin and globulin, while a significant  difference was observed (P ≤ 0.05) in the protein ratio,  where the T3 injection treatment outperformed the control  treatment and the rest of the experimental treatments, as T3  recorded 6.65 g/100 ml protein compared to 6.35 g/100 ml  for the control treatment T1.