Influence of Ammonia Gas on Histomorphometry and Histopathology of Broiler Chicken Tracheas

Abstract

The aim of the present study was to analyze the histomorphology and histopathology of broiler chicken tracheas submitted to different levels of ammonia gas. The experiment was conducted during different seasons in 2019 in the city of Garanhuns, Brazil. Three sheds with rice hull bedding were used: Shed 1, new bedding; Shed 2, reused bedding; Shed 3, reused bedding with an increase in moisture. Twentyeight birds were housed per shed for a 42-day production cycle. On days D0 (control group), D7, D21, D35 and D42, seven birds per shed were euthanized. Fragments of the trachea were collected and placed into plastic containers with 10% buffered formalin solution (pH 7) for 24 h, subsequently undergoing routine histological processing. The thickness of the tracheal mucosa was measured using digital images, considering ten equidistant points as being separated by 100 µm. Histopathological lesions were analyzed considering distribution and intensity. The birds in Shed 2 (reused bedding) had greater quantity and severity of histopathological lesions, but the differences did not reach statistical significance. Regarding histomorphometry, birds reared in the higher temperature period had thicker tracheal mucosa at the end of the production cycle (D35 and D42) compared to those raised in the cooler temperature period. In conclusion, the difference in bedding did not significantly alter the tracheal mucosa of the birds, whereas temperature exerted an influence on the thickness of the trachea at the end of the production cycle.