Rehearsal For Thesis Presentation

Ammonia (NH₃) is one of the most common air pollutants in poultry houses. High concentrations of ammonia are usually caused by intensive farming systems and infrequent litter replacement. Past studies have shown that exposure to ammonia above 25 ppm can reduce growth performance in broilers, cause damages to multiple organs, weaken the immune response, and even lead to respiratory diseases. Recently, some phytogenics haven been with growth-promoting effects in broilers, including extracts from Compositae plants for their anti-inflammatory activities, , Fabaceae plants with anticoccidial effects, Lamiaceae plants with strong an antioxidant activity and immune-boosting potential, and Rutaceae plants with gut stability and fat metabolism. This study aimed to explore the effects of dietary phytogenic supplementation on growth performance and respiratory tract health  of broilers under ammonia exposure. A total of 280 Arbor Acres broilers were divided into 10 treatment groups: a control group (Con), four phytogenic groups (TH1 from Compositae, TH2 from Fabaceae, TH3 from Lamiaceae, and TH4 from Rutaceae), and their counterparts with ammonia exposure (CN, 1N, 2N, 3N, 4N). Each group had four replicates. The control group received a basal diet, while the phytogenic groups were fed diets supplemented with 0.1% of the corresponding phytogenics. From day 14 to 28, the ammonia groups were exposed to 30 ppm ammonia for 1.5 hours every two days. Birds were sacrificed on days 28 and 35 for assessments of growth performance, blood biochemistry, and histopathology. In contrast to the control group, ammonia exposure significantly reduced body weight and feed intake, impaired the tracheal barrier integrity, induced inflammatory cell infiltration, excessive goblet cell proliferation and mucin over-production, and increased macrophage infiltration. Additionally, serum IL-1β levels were significantly elevated. Dietary phytogenic supplementations alleviated the inflamed damages in the trachea by ammonia irritation and differentially improved growth performance.  In conclusion, ammonia exposure decreases growth performance in broilers and induces inflamed damages in the trachea. Supplemental phytogenics relieve tracheal inflammation under ammonia exposure and improve growth performance in broilers.
 
 
Keywords: broilers, ammonia, phytogenics, respiratory tract, inflamed damages

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