Purified lipopolysaccharides (LPS) from 16 serotypes of Pasteurella multocida were complexed with Aspergillus fumigatus ribosomes. The complexes were used as inocula to prepare antisera, in chickens, for somatic antigen typing by the gel diffusion precipitin test (GDPT). Antisera made against 15 of 16 LPS reacted with their respective specific heat-stable antigens in the GDPT and homologous LPS in the passive hemagglutination test. Antisera could not be made against serotype 15 LPS. Correlation was not observed between intensity of the precipitin reaction in the GDPT and titer to homologous LPS in the passive hemagglutination test. Most antisera cross-related with other heat-stable antigens of other serotypes in the GDPT. Many of these cross-reactions were eliminated by dilution. Cross-reactions that occurred in the GDPT with antisera made against LPS of serotypes 2, 5, 7 and 8 could not be eliminated by dilution.

The relative myocardial irritant properties of halothane, isoflurane, and pentobarbital were evaluated in chickens. Sixteen adult male broiler chickens were randomly assigned to 1 of 3 groups: group-1 chickens were anesthetized with pentobarbital (30 mg/kg, IV), group-2 chickens were anesthetized with halothane (end tidal halothane 1.2%), and group-3 chickens were anesthetized with isoflurane (end tidal isoflurane 2.1%). Birds in any 2 of the 3 treatment groups were tested on any 1 day. Local anesthesia was induced, and blood pressure, heart rate, ECG, and blood gas variables were measured before general anesthesia was induced. Positive-pressure ventilation with an inspired O2 fraction > 0.95 was adjusted to result in an end tidal CO2 concentration that reflected a PaCO2 similar to that obtained prior to anesthesia and ventilation. All measurements were repeated. The threshold for ventricular fibrillation in response to electrical stimulation of the heart was then determined for all birds. Effects of anesthesia on hemodynamic and blood gas variables were similar in all 3 groups. Compared with halothane or pentobarbital, isoflurane anesthesia resulted in a significantly (P < 0.05) lower threshold for electrical fibrillation of the heart.

Introduction: The present study aimed to investigate the effect of Enterococcus faecium EF55 on chickens, as well as its influence on proliferative activity of epithelial intestinal cells after infection with Salmonella enterica serovar Enteritidis phage type 4 (SE PT4). Moreover, the length and area of duodenal and jejunal villi of the birds were examined.

Domestic poultry is a natural reservoir of Campylobacter, the host–pathogen interaction being predominantly asymptomatic. This study investigated whether chickens remain asymptomatic partly because of lactic acid bacteria (LAB).

Introduction: The main problem in poultry farming is the difficulty in producing food of animal origin without using antibacterial agents. Because most antibacterial compounds are dispensed in water, some water supply systems can be contaminated by antibiotics which are then administered to the animals unintentionally. This can lead to unexpected increases in antibiotic residues in food of animal origin. The aim of the present study was to determine whether the constant exposure of chicken broilers to enrofloxacin affects the withdrawal time of a therapeutic doxycycline that is intentionally administered to the chickens.

Introduction: Avian pathogenic Escherichia coli (APEC) is a leading cause of extraintestinal infection and heavy economic losses. Imparting immunity after vaccination with live attenuated strain vaccination is an ideal strategy for infection control. This study considers an FtsK knockout mutant strain as a candidate. Material and Methods: An FtsK knockout mutant of APEC strain E058 was constructed and the pathogenicity of the mutant and wild-type strains was further evaluated in chickens. Results: The 50% lethal doses of each strain for one-day-old specific-pathogen-free (SPF) chickens challenged experimentally via trachea were 105.5 and 107.0 colony-forming units (CFU) respectively. Chickens challenged with the wild-type strain exhibited typical signs and lesions of avian colibacillosis, while those inoculated with the mutant strain showed mild pericarditis and pulmonary congestion. The growth rate of the FtsK mutant strain was much slower than the wild-type strain in the heart, spleen, liver, and lung of infected chickens. Conclusion: These results indicated that the APEC FtsK mutant can be attenuated for chickens, and that this mutant has the potential for the development of an APEC vaccine.

This study was carried out on serum samples collected from broiler breeder chicken flocks vaccinated with avian influenza (AI) H5N1 inactivated vaccine. These flocks included 23 flocks aged 13 to 47 weeks reared in close houses in 7 sites; two vaccinated breeder flocks for HI antibody monitoring by 5 weeks interval samples and 8 flocks aged 41 weeks reared in different sites with identified females and males samples. The vaccine was used in a dose of 0.2 ml at 1 day in hatchery and revaccinated with 0.5 ml at age of 18 days, 19- 20 weeks and 40 weeks. Hemagglutination inhibition (HI) test was carried out against homologous antigen. The study pointed out that AI H5N1 inactivated vaccine under field application induced irregular and low HI titres following the 1st two doses ranged from log 2 0.0 to 4.15 with great variation between flocks, where samples with titre 0-2 ranged from 20 to 100%. The 3rd dose at 19-20 weeks was essential to elevate HI titres 3.25 to 7.44 with more homogenizes flock immunity and lower percentage of titres 0-2 ( 0-20 %) and as measured by HI test. Revaccination of layer flocks at 40 weeks (fourth dose) improves flock immunity facing stress of egg production as evaluated by HI (5.52 - 6.33) and lower negative percentage (5.5-11.7%). Monitoring of breeder flock every 5 weeks is essential to detect proper time of revaccination as each flock has its HI antibody curve. There was a difference in HI tit re rang log 2 0.33 to 1.2 between male and female chicks reared in the same house, but this variation not affecting flock mean. Birds at aged 41 weeks having titres < log2 3 (Seronegative) were protected when exposed to contact with infected flock as showed no clinical signs or change in HI titres after 12 days. In conclusion the usage of homologous inactivated H5N1 vaccine in 4 doses in layer flocks was of value in improving chicken immunity to AI H5N1 wild strain circulate in our field