تاثیر موقعیت قرارگیری تخم مرغ‌ها در دوره انکوباسیون بر تلفات جنینی و حجم مایع آمنیوآلانتوئیک در مرغ های مادر تخم‌گذار جهت استفاده از آن ها در تکثیر ویروس

The numerous apparent malformations of eggs from laying breeder flocks are affected by the increased age of the flocks. The bulking and spinning of eggs causes them to be placed in small end up (SEU) condition in the incubation period and eventually inoculation of the virus is done incorrectly. Present study was designed to investigate the effect of egg condition on embryos deaths, amnio-allantoic fluid volume, and the influenza virus replication rate. 1200 one-day-old embryonated chicken eggs from breeder flock at 60-65 weeks of age were divided in three groups. The first group underwent the incubation period before and after inoculation of the virus in large end up (LEU) condition. The second group spent the incubation period pre and post inoculation of the virus in SEU and LEU positions, respectively. The third group passed the incubation period before and after the inoculation in SEU condition. Prior to inoculation of the virus, all groups were incubated for 11 days at 37.6°C and 60% relative humidity (RH), and turned 32 times daily. After inoculation, the eggs were incubated for three days at the same conditions but without turning. Ultimately, in each group, the amnio-allantoic fluid was collected and the percentage of embryos deaths was determined. Titration assays were performed using hem agglutination (HA) and egg infective dose 50 (EID50) tests. All experiments were performed in three replicates. The results showed that the percentage of embryos deaths was 3:1 in the second group in comparison to the first group. In the third group, casualties were 100%. Mean of extracted amnio-allantoic fluid volume from total eggs of first group in comparison to the second group was approximately 8:1. There were significant differences between the groups in all factors (p<0.05). Based on the current study findings, the condition of eggs during the incubation period before and after inoculation of the virus has a direct effect on embryos deaths, and the volume and quality of the amnio-allantoic fluid.