Corticosterone in ovo Injection Effects on the Development of Iraqi Native Chicken Embryos

Abstract

Background: Corticosterone is a major glucocorticoid hormone in the plasma of birds. It is produced in the adrenal gland and transferred to the eggs after 1-2 days of circulation in females by distributing within the yolk. So, this study aimed to evaluate Iraqi native chicken hatching eggs with different levels of corticosterone hormone on embryonic development. Methods: Three hundred Iraqi native hatching eggs from 30 weeks old breeds were utilized in this research. Eggs were divided into five treatments and three replicates (20 eggs for each). Eggs were injected with different levels of corticosterone hormone as follows: Control group without injection, Sesame oil group: Injected with 5 µl of sterile sesame oil only, Group 1: Injected with 0.25, Group 2: Injected with 0.5 and Group 3: Injected with one ng of corticosterone hormone dissolved with sterile sesame oil. The embryonic test was checked after 72 hours, 7 days, 14 days and 18 days of egg incubation. After hatching, hatchability from fertile eggs, early, intermediate and late embryonic mortality, life and dead pipped eggs as a percentage of fertile eggs were measured. Result: Results showed a significant increase (P≤0.05) in embryo length for Group 1 and a significant decrease (P≤0.05) in amniotic fluid and amniotic weight percentage for Group 2, a significant decrease (P≤0.05) in amniotic fluid, amniotic sac membrane percentage, hatchability early embryonic mortality percentage for Group 3 compared with a control group. In conclusion, a high concentration of corticosterone hormone in Iraqi native chicken hatching eggs causes an increase in embryo length, amniotic fluid and amniotic weight percentage. Also, it causes a decrease in amniotic fluid, amniotic sac membrane percentage, hatchability and early embryonic mortality percentage.