Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 19, 2005
Publication Date: September 1, 2005
Citation: Solis Del Los Santos, F., Tellez, G., Farnell, M.B., Balog, J., Anthony, N.B., Pavlidis, H.O., Donoghue, A.M. 2005. Hypobaric hypoxia in ascites resistant and susceptible broiler genetic lines influences gut morphology. Poultry Science. 84(9):1495-1498. Interpretive Summary: Genetic selection based on rapid growth rates, improved feed conversion and increased body weights has led to a predisposition to ascites (hypertension) in broiler populations, which is exacerbated at high altitudes where less oxygen is available. Researchers have recently developed lines of chickens that are ascites resistant (26.0% ascites mortality, RES) and ascites susceptible (98.6% ascites mortality, SUS). One objective of this research was to determine the effects of high altitudes on the gut of these genetic lines. In two separate trials, pedigree broiler chickens (n = 480; 40 groups of 12 birds per group) were randomly assigned to cages in a hypobaric chamber (simulated 2,900 m above sea level) or a matching local altitude chamber (390 m above sea level). Ascites incidence was characterized by heart enlargement and fluid accumulation in the abdominal cavity. At the end of the study, on d 42 all surviving birds were euthanized and evaluated for the presence of ascites and gut tissues were collected from the duodenum and lower ileum from 5 chickens/line/altitude/trial for microscopic analysis. At a high altitude, ascites incidence was lower in the RES line (20.9 and 3.7%) than the SUS line (86.4 and 66.9%, Trials 1 and 2, respectively). No ascites incidence was observed at a local altitude. Under high altitude conditions the duodenum was better developed in the RES line than the SUS line. No differences were observed in the ileum with either group. The reduced development of the duodenum of birds selected for ascites susceptibility suggests reduced enteric function and may provide clues as to why these birds have increased incidence of ascites.