ABSTRACT Due to the genetic similarity of pathogenic Escherichia coli isolated from birds and pathotypes of human origin, it is suggested that they have a common ancestor and may exchange virulence-associated genes. This study aimed to detect virulence-associated genes in E. coli strains isolated from the Red-browed Amazon parrot (Amazona rhodocorytha) kept at a conservation institute in Brazil. High genetic variability in virulence was observed, since 12 virulence profiles were found among 14 strains. The number of virulence-associated genes of single strains ranged from 5 to 22 out of 33 genes tested, and only one strain did not present any virulence genes. Regarding adhesion genes, most strains presented from two to five genes, and crlA (85.7%) and fimC (85.7%) were the most frequent. Frequencies were similar for invasion and iron acquisition genes. Variations among genes were observed for serum resistance and toxin-related genes. Some of the E. coli strains isolated from parrots presented virulence genes that are commonly associated with pathotypes of human origin, including newborn meningitis E. coli, uropathogenic E. coli, and sepsis-associated E. coli. It is noteworthy that some of these genes were present in the majority of the analyzed strains. Our results indicate that these strains detected in clinically healthy parrots can be potential reservoirs of several virulence-associated genes. These genes can be transmitted to other E. coli strains, including those that affect humans. These E. coli strains present a high pathogenic potential of virulence-associated genes in extraintestinal pathogenic E. coli strains.

Broiler chicks belonging to two poultry companies, A and B, with different breeders' vaccination programs were challenged with a very virulent strains of infectious bursal disease virus (vvIBDV), genotyped as G11. Birds were separated in four groups, two vaccinated at the first day of life and two unvaccinated. They were then challenged at the 1st, 4th, 7th, 10th, 13th, 16th, 19th and 22nd days. At every day of challenge, before and after the procedure, the following data were collected from each group: Bursa of Fabricius (BF) relative weight, BF diameter, BF for histologie examination, serum for measuring antibodies against IBDV through the ELISA and clinical evaluation of IBD. The results obtained have shown a non-significant drop in antibody level between the vaccinated and the unvaccinated groups. When analyzing the different results, it could be established that an ELISA titre of 3,4 log10 was the cutoff point between healthy and sick birds. Regression equations were built to determinate the best moment for vaccination and also the ELISA log titre birds what could present in a given age. Based on that, chicks from Company A should receive a vaccine against IBD from the 6th to 7th day of age, while the ones from Company B should get it between the 11th and the 12th day of age. Finally, the overall results suggest that the birds should not be vaccinated at one day old, and also that the breeders' different vaccination schemes resulted in progenies with different levels of maternal protection, and as a consequence the same vaccination plan should not be applied indiscriminately to broilers from different poultry companies.

Infectious Bursal Disease (IBD) is a chicken disease economically important for the poultry industry in function of the immune depression that it causes. Disease control is made with different vaccines and vaccination programs. In present work, the pathogenicity of 3 intermediate vaccines (I1, I2 and I3), 2 intermediate more pathogenic (IP1 and IP2) and 3 vaccines containing strong virus (F1, F2 and F3) was evaluated. Birds vaccinated with IP1, IP2, F1, F2 and F3 showed significantly lower bursa size in relation to control animals and animals vaccinated with I1, I2 and I3. On the other hand, vaccines I1 and I3 induced antibody titers higher than the control and lower than I2, IP1, IP2, F1, F2 and F3. Histological scores showed that vaccines I1, I2 and I3 induced similar injury degree, although I2 and I3 were not different from the control, whereas I1 was slightly different. Strong vaccines induced more pronounced lesions than the other tested vaccines. These findings suggest that strong vaccines are able to cause severe bursal injuries. However, bursometry and relative weight of the bursa of Fabricius were considered inadequate to evaluate vaccine pathogenicity. Moreover, strong vaccines induced higher antibody titers than the other vaccines, although some intermediate vaccines induced similar titers.

Uma atividade com a magnitude da avicultura, que usa equipamentos de última geração e serviços atualizados, é levada, na maioria dos casos, a tomar decisões que envolvem todos aspectos de produção, apoiada em critérios subjetivos. O presente trabalho objetiva estudar a utilização das redes neurais artificiais para serem usadas na predição dos parâmetros de desempenho das aves em recria, pertencentes a uma integração avícola sul-brasileira. Foram utilizados os registros de 11 lotes de reprodutoras pesadas para a análise por redes neurais artificiais, no período compreendido entre 09/11/97 a 10/01/99. Os dados utilizados corresponderam a 273 linhas de registros semanais. Os modelos de redes neurais artificiais foram comparados e selecionados como melhores, baseados no coeficiente de determinação múltipla (R²), Quadrado Médio do Erro (QME), bem como pela análise de gráficos, plotando a predição da rede versus a predição menos o real. Os autores concluem que é possível explicar os parâmetros de desempenho das aves em recria, através da utilização de redes neurais artificiais. A técnica permite a tomada de decisões por parte do corpo técnico, baseadas em critérios objetivos obtidos cientificamente. Além disso, esse método permite simulações das conseqüências de tais decisões e fornece a percentagem de contribuição de cada variável no fenômeno em estudo.

An economic activity with the magnitude of the poultry industry, which uses top line equipment, generally is lead to make decisions involving all production parameters, based in subjective criteria. The aim of this paper is to study the use of artificial neural networks to predict performance parameters in breeding birds, belonging to a South Brazilian poultry farm. Data from 11 broiler breeder flocks was recorded between November, 11th 1997 and October, 1st 1999. These data were processed by artificial neural networks. They corresponded to 273 data lines related to weekly recordings. The artificial neural networks models were compared and the best was selected, based on its determination coefficient, (R²), Mean Squared Error (QME), and by graphical analysis of the plot of network predictions versus the predictions minus the actual data. The authors conclude that it is possible to explain the performance parameters of breeding birds with the use of Artificial Neural Networks. The method allows decision making by the technical staff, based on objective criteria, scientifically obtained. Besides that, this method allows the simulation of consequences of these decisions and estimates the contribution of each variable used in the phenomena under study.