Physiological, management and environmental triggers of the ascites syndrome: A review

Abstract

In meat-type chickens, an inadequacy of vascular capacity for blood flow through the lung to provide the tissues with the oxygen needed for rapid growth is the primary cause of pulmonary hypertensioninduced ascites. There are a variety of other factors that can trigger the ascites syndrome. These factors may cause increased blood flow because of a higher metabolic rate (cold, heat, certain nutrients, chemicals, etc.) or they may cause pulmonary hypertension-induced ascites in rapidly growing chickens because of greater resistance to blood flow in the lung by: (i) increased blood viscosity or red blood cell rigidity; or (ii) reduced vascular capacity in the lung. Some secondary factors, such as high sodium from salt in feed or water, may cause both increased flow and increased resistance to flow. Measures to reduce the ascites syndrome must address the primary genetic cause of insufficient vascular flow capacity in the lung and oxygen delivery to tissues, and the secondary factors that increase oxygen requirement, blood flow and the resistance to blood flow in the lung.

Effect of chronic hypoxia during embryonic development on physiological functioning and on hatching and post-hatching parameters related to ascites syndrome in broiler chickens

“…At sea level, oxygen makes up 20.9% of the atmosphere and the equivalent percentage of oxygen drops approximately 1% for every 500 m rise in altitude (Julian, 2000). The purpose of the present study was to test the hypothesis that there is a metabolic adaptation to environmental hypoxia in broiler chickens (Buys et al, 1998;Hassanzadeh et al, 2002).…”

“…Such occurrences among fast growing lines are even more apparent under conditions that impose an additional metabolic load on the birds, such as low ambient temperature and high altitude (Julian, 1993(Julian, , 2000Hassanzadeh et al, 2001Hassanzadeh et al, , 2003. This may not only be related to an increased oxygen demand, but also to the supply of oxygen that could be involved or altered in these lines selected for rapid growth and efficient food conversion (Decuypere et al, 2000).…”

Effect of early feed restriction on physiological responses, performance and ascites incidence in broiler chickens raised in normal or cold environment

“…In a cold environment, the growth rate is faster and metabolic rate rises to increase heat production and maintain normal body temperature (Julian, 2000). Consequently, cardiac output increases to supply the oxygen required for metabolism causing increased vascular pressure in the lung and pulmonary arteries (pulmonary hypertension).…”

“…Consequently, cardiac output increases to supply the oxygen required for metabolism causing increased vascular pressure in the lung and pulmonary arteries (pulmonary hypertension). Pulmonary hypertension triggers series of events, which finally lead to the ascites syndrome (Julian, 2000 and2007). During cold stress several studies have reported important physiological changes, including classic hematological changes and increased right ventricle weight per total ventricle weight (RV : TV) ratio (Yahav et al, 1997;Luger et al, 2003;Ipek and Sahan, 2006), but there is only very little or no information on the other physiological responses such as blood chemical alterations.…”

Lipid Peroxidation in the Plasma, Lungs, Heart and Liver of Broilers Fed a Grape Seed Extract and Raised at 2278 m of Altitude

“…High altitude, poor ventilation (Julian, 2000), low temperature (Fathi et al, 2011), and ad libitum feeding (Rodríguez-Ortega et al, 2014) are predisposing factors for AS. High altitude reduces the partial pressure of oxygen (PO 2 ) in the inspired air (hypoxia, Wideman et al, 2013), which in turn produces hypoxic broilers (Ruiz-Feria & Wideman, 2001).…”