Congenital abnormalities in dead-in-shell chicks associated with mixed bacterial infections

Determination of the chick embryonic developmental period at which embryonic mortalities occur could help in establishing the cause of such mortalities. The late stage of embryonic development has particular importance due to its dramatic effect on life after hatching. This study was conducted to investigate the occurrence, frequency and bacterial isolates from dead-in-shell chick embryos in Northern Jordan. A total of 1,000 unhatched eggs were collected at hatching day from 10 hatcheries located in Northern Jordan. Out of 1,000 eggs, 357 (35.7%) were fertile, of which 210 (58.8%) were dead-in-shell embryos. Approximately 50.5% of the dead embryos displayed abnormalities, including neck muscles with subcutaneous petechial haemorrhages (44.3%), beak abnormalities (3.8%), eye deformities (1.9%) and anencephaly (0.5%). Sixty-six bacterial isolates were identified from 82 samples from the dead-in-shell embryos. The isolates were 22 (33.3%) Escherichia coli, 18 (27.3%) Klebsiella pneumoniae, 14 (21.2%) Staphylococcus aureus, 5 (7.6%) Pseudomonas aeruginosa, 4 (6.1%) Salmonella enteritidis, 2 (3%) Bacillus cereus and 1 (1.5%) Proteus vulgaris. Mixed growth was also recorded in 16 (19.5%) samples. There was a significant (P < 0.05) association between Escherichia coli as a bacterial isolate and the occurrence of neck and beak abnormalities. In this study, infection of check embryos with several bacterial species, particularly Escherichia coli, was identified as an important cause of multiple congenital abnormalities involving the neck and beak of unhatched chicks.