Cardiac index, oxygen delivery, and tissue oxygen extraction in slow and fast growing chickens, and in chickens with heart failure and ascites: a comparative study

The present study examines the differences in blood gas parameters, cardiac output, cardiac index, oxygen delivery and tissue oxygen extraction in slo w growing chickens (leghorn and feed restricted broilers), fast growing chi ckens (broilers fed ad libitum) and chickens with fulminant heart failure a nd ascites, In comparison to leghorns, broiler chickens had lower pO(2) and O-2 saturation levels in venous blood (P < 0.001), At the age of 35 days, broilers had arterial and venous pO(2) significantly lower than 7-day-old b roilers (P < 0.05). Overall, blood pO(2) and O-2 saturation tended to decli ne, and CO2 content tended to increase with age. Chickens developing ascite s had lower blood pO(2) and O-2 saturation levels, and higher blood CO2 con tent in comparison to normal chickens (P < 0.05), In comparison to other ch ickens, ascitic chickens had the lowest pO(2) and O-2 saturation, and highe st CO2 content in both venous and arterial blood (all P < 0.001), Broilers at 35 days of age had higher arterial O-2 content than leghorn chicks, and there were only minor differences between normal and ascitic chickens. Howe ver, ascitic chickens had the lowest venous O-2 content (P < 0.001), but th e highest tissue O-2 extraction index (P < 0.001), Cardiac index was higher in leghorn chicks than in broilers (P < 0.001), Ascitic birds had the lowe st cardiac index (P < 0.001). Oxygen delivery was higher in leghorns than i n broilers (P < 0.001), Ascitic birds had the lowest oxygen delivery index. The present study has identified significant differences in previously une xamined performance indicators of the cardiovascular system between slow gr owing chickens, fast growing chickens and chickens with heart failure, Low cardiac index in broiler chickens appears to be the key haemodynamic proble m leading to hypoxaemia and ultimately cardiovascular failure in East growi ng broilers.