This study was designed to provide a rapid highly protective passive immunization of chickens against necrotic enteritis (NE). This aim was established by preparation of NE alpha toxin IgY in chicken egg yolk, such preparation was found to have specific anti NE alpha toxin titer 40 I.U by SNT and 0.237 optical density (OD) by ELISA. It was found that oral administration of 40, 20, 10 and 5 IU/ml of IgY / poult after experimental infection with Clostridium perfringens type A, resulted in protective rates of 96%, 88%, 80% and 60% respectively. Chickens' sera of passively immunized birds showed antibody titers of 1, 2 and 1.5 I U in the first, second and third days' post immunization respectively. It was concluded that IgY for NE alpha toxin type A could be used successfully to protect or even minimize the severity of the disease during possible outbreaks.

A PCR-aided monitoring of verotoxin-producing Escherichia coli (VTEC) was performed over the period of 12 months by using fresh feces collected monthly from 5 dairy cows that had been identified as VTEC carriers. The PCR products were confirmed to be verotoxin genes by Southern hybridization using a gene fragment of verotoxin 2 as a probe. Although seasonal variation of VTEC shedding seemed to depend on each cow, several factors may have influenced the frequency of detection. Shedding of VTEC tended to be reduced during grazing from the middle of May up to the beginning of October. Only one cow was positive for VTEC in August. Dry-off was also suggested to have a depressive effect on VTEC shedding, i.e. 3 of 4 dry cows showed no shedding of VTEC. Contrary to these factors, winter or indoor rearing tended to increase VTEC with only 5/24 samples being negative during the period from November to April. Total VFA concentration was higher (p<0.05) in VTEC-positive feces than in VTEC-negative feces, while fecal pH and VFA proportions were not different. Partial sequences of verotoxin genes from feces of 4 VTEC-positive cows were nearly identical (99-100%), suggesting that gut bacteria sharing the same gene were distributed among the cows. The present results indicate that grazing and dry-off could be factors which reduce VTEC shedding, while winter/indoor rearing may be a factor which increases the shedding, possibly through on-farm interactions.

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Veterinary Serum and Vaccine Research Institute (VSVRI ) objected to producing highly efficient vaccines from reference or local isolates according to the international specifications for protecting animals and poultry against different diseases and preparing combined vaccines to save effort, time and money. VSVRI produces various types of vaccines such as live attenuated viral poultry, live attenuated viral animal vaccines, live attenuated Bacterial animal vaccines and Inactivated viral animal vaccines. These vaccines are subjected to quality assurance through seven methods with different techniques. Validity and measurement uncertainty for results were applied in the evaluation of results of the following: Titration of virus content using egg inoculation through Chorioallantoic Membrane (CAM), Intra-allantoic (IA) and Tissue Culture (TC). Determination of antibody titer using ELISA, HI and VNT techniques. Finally, enumeration of aerobic bacterial count for living attenuated Bacterial vaccine by culture technique. Homogeneity and stability results for all vaccines were accepted criteria according to TS/ ISO 22117. The reproducibility component of the TC technique was higher while the Bias was lower than other different routes of egg inoculation. In conclusion, the accuracy of TC technique is better than the egg inoculation technique which will reflect on the measurement of uncertainty. There is no significant change in the final measurement uncertainty of different routes of egg inoculation. In comparison, there is a variance between bias accuracy and reproducibility precision due to the equation of measurement of uncertainty depending on all processes performed in test accuracy and precession.