Muscular growth and cardio-respiratory function in broiler chickens

Abstract

This review focuses on the influence of selecting broiler chickens essentially for rapid growth, high breast yield and low feed conversion ratio on the frequency of cardiovascular and respiratory failures. Broilers show a reduced lung volume relative to body weight, a lower ability to fix oxygen in blood, a higher blood viscosity and more frequent cardiac arrythmias as compared to slow growing chickens. These factors could explain their predisposition to pulmonary hypertension complicated by ascites. Because of a relatively slower development of their cardio-respiratory system, some broilers can hardly supply efficiently their muscular tissues with oxygen. Their ability to adapt to a stimulation of the metabolism by environmental factors (climate, altitude, high protein or metabolic energy level feeding regimen) is limited. Any increase of the needs of oxygen directly stimulates a relative hypoxia. Geneticians are looking for new selection criteria on pulmonary, haematological and cardiovascular characteristics matching with growth characteristics.