Further insights into the prevention of pulmonary hypertension syndrome (ascites) in broiler: a 65-year review
Md. Emran Hossain, Nasima Akter
Abstract
SUMMARYPulmonary hypertension syndrome (PHS) refers to the accumulation of non-inflammatory hepatic transudate in the peritoneal cavity of the broiler chicken due to increased pulmonary hypertension, elevated tissue oncotic pressure, hepatic fibrosis and vascular damage. It is a global threat for the broiler industry which progresses through wide ranges of physiological and metabolic changes because of adverse dietary, environmental and hereditary factors. Noticeable changes include generalised oedema, hydro-pericardium, fibrosis of epicardium, hepato-abdominal oedema, distended-flaccid heart, right ventricular hypertrophy, variable hepatic changes, pale comb and elevated blood haematocrits. The aetiology of the disease is complex but usually results because of imbalanced cardiac output and failure of the pulmonary system to adapt elevated blood flow. The condition does not transmit within healthy birds but causes massive economic losses through carcass condemnation and flock mortality. Genetic factors, fast growth, higher elevation, extreme cold, poor ventilation, low blood pH, high-intensity lighting, high nutrient density and pellet diet are the main predisposing factors of PHS. However, selection of suitable genotype, supplementation of desired amino acids, flax oils, L-carnitine, co-enzyme, feed additives, certain vitamins, inorganic salts, restricted feed consumption, regulation of incubation temperature and appropriate veterinary approaches could ameliorate PHS. Designing new parent lines considering balanced muscle-to-heart and lung ratio, better management of breeder flock, optimisation of incubation and post-hatch temperature, humidity, ventilation and recommendation of strain-specific fortified broiler diet may shed new light to the emerging crisis of PHS worldwide.