Efeito da fumigação de nascedouros com formaldeído sobre o trato respiratório e desempenho de frangos de corte

Abstract

A study was conducted with the aim of assessing the effect of fumigating eggs in the hatching environment with 37% formaldehyde, on the micro- and ultrastructural histologic alterations in the respiratory tract of recently-hatched broiler chickens, and on the productive performance of broiler chickens. The treatments were defined in accordance with the time of exposure and concentration of the formaldehyde used in the hatching environment, as follows: T1 (formaldehyde changed every six hours); T2 (formaldehyde changed every nine hours); T3 (formaldehyde changed every twelve hours); and T4 (control group, no formaldehyde was used). Samples of the chicken trachea and lungs were collected after exposure to formaldehyde and examined under light microscope and transmission electronic microscope to evaluate structural alterations. The following lesions were observed: Mucous accumulation; areas of deciliation; ciliar agglutinations; areas of desquamation; heterophil infiltrations. To evaluate the productive performance 600 chickens from each treatment (formaldehyde concentrations) were used, which were housed in an experimental shed. The statistical design used for all the analyses was entirely casualized. For statistical analysis of the results obtained from the ultrastructural evaluations, the Wilcoxon non-parametric test was used. For statistical analysis of the results obtained from the microstructural evaluations, the Kruskal-Wallis non-parametric test was used. The Student s-t statistical test ( = 0,05) was used to verify differences between the means of the performance data of the birds when there was normal distribution of the data; when the distribution was not normal, the Wilcoxon non-parametric test was used to verify differences between groups. For all the variables a level of significance of = 0.05 was considered. The use of formaldehyde gas during the entire hatching process caused ultra- and microstructural alterations in the trachea and lungs of broiler chickens, the most frequent being areas of deciliation, ciliar membrane rupture, ciliar agglutination, areas of desquamation in the epithelium and heterophil infiltrations, however, no statistical differences between the treatments were found. Exposure of the chickens to formaldehyde in the hatching machine did not influence the productive performance of these birds. Therefore, at this stage the use of formaldehyde gas must be minimized, due to the ultra- and microstructural alterations in the trachea and lungs of newly hatched chickens, and the poultry industry must develop a method of disinfection that is less damaging to the upper respiratory tracts of newly hatched chickens.