Comparing the effectiveness of egg disinfectants against bacteria and mitotic indices of developing chick embryos

Total bacterial counts on hatching eggshell surface were significantly (P < 0.05) reduced as a result of using all disinfectants with different concentrations and formaldehyde fumigation treatments compared with those for eggs before treatment except for those subjected to water only which are considered as control with water. Chemical disinfectants significantly reduced the eggshell total bacterial count from 7.07 Logs to 2.41 Logs with 65.9% reduction and decreased again to 1.96 Logs with 72.3% reduction before setting in the incubator. Also, natural disinfectants significantly reduced the total bacterial count from 7.0 Logs to 1.86 Logs with 73.7% reduction and decreased again to 1.34 Logs with 81% reduction before setting in the incubator. Whereas, treatment with formaldehyde fumigation significantly reduced the bacterial count from 7.07 Logs to 2.53 Log with 64.2% reduction, but the bacterial count had increased numerically again during storage and before setting in the incubator to 4.20 Logs. Chemical disinfectant effects on developing chick embryos resulted in retarded growth as reflected by malformed limbs and beaks and muscle weakness was seen in a few hatched chicks. The mitotic indices of the spinal cord for chicks from egg treated by cumin 0.2% at 3rd and 4th day of age are slightly higher being 5.5% and 4.8% respectively, than those for other treatment and control groups. The mitotic index revealed that there was a significant (P < 0.05) difference between all disinfection and control groups on days 4, 7 and 10 of incubation with respect to skin systems, whereas skin system of newly hatched chicks did not demonstrate any significant differences between mitotic indices of experimented groups. Mitotic indices of embryonic dermal system on days 4 and 10 of incubation were slightly higher for natural disinfectant (being 4.7 and 0.1) compared with those for the chemical disinfectant (being 4 and 0.6), formaldehyde fumigation (being 3 and 0.4) and control group (being 4 and 0.9).