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

Abstract

The present study exam ines the differences in blood gas param eters, cardiac output, cardiac index, oxygen delivery and tissue oxygen extraction in slow growing chickens (leghorn and feed restricted broilers), fast growing chickens (broilers fed ad libitu m) and chickens with fulm inant heart failure and ascites. In com parison to leghorns, broiler chickens had lower pO2 and O2 saturation levels in venous blood (P , 0.001) . At the age of 35 days, broilers had arterial and venous pO2 signi® cantly lower than 7-day-old broilers (P , 0.05). Overall, blood pO 2 and O2 saturation tended to decline, and CO 2 content tended to increase with age. Chickens developing ascites had lower blood pO2 and O2 saturation levels, and higher blood CO 2 content in com parison to normal chickens (P , 0.05). In com parison to other chickens, ascitic chickens had the lowest pO2 and O2 saturation, and highest CO 2 content in both venous and arterial blood (all P , 0.001) . Broilers at 35 days of age had higher arterial O2 content than leghorn chicks, and there were only m inor differences between norm al and ascitic chickens. However, ascitic chickens had the lowest venous O2 content (P , 0.001) , but the highest tissue O2 extraction index (P , 0.001) . Cardiac index was higher in leghorn chicks than in broilers (P , 0.001) . Ascitic birds had the lowest cardiac index (P , 0.001). Oxygen delivery was higher in leghorns than in broilers (P , 0.001) . Ascitic birds had the lowest oxygen delivery index. The present study has identi® ed signi® cant differences in previously unexamined performance indicators of the cardiovascular system between slow growing chickens, fast growing chickens and chickens with heart failure. Low cardiac index in broiler chickens appears to be the key haem odynam ic problem leading to hypoxaem ia and ultim ately cardiovascular failure in fast growing broilers. IntroductionAscites is the excessive accumulation of¯uid in body coelomic cavities. This condition is the cause of signi® cant econom ic losses in the comm ercial broiler industry throug hout the world. In clinical terms, ascites is a non-spe ci® c sign and m ay have several causes. In broiler chickens, ascites is most often associated with heart failure, but the aetiology of ascites is poorly understood. A m arked decline in heart rate (HR) is a consistent pathophysiological feature in fast growing broiler chickens prone to ascites (Olkowski & Classen, 1998). In normal chickens, an increase in HR begins shortly after hatching, but HR plateaus around 4 weeks of age, and then slowly declines until m aturity (Ringer et al., 1957;Flick, 1967; Tazawa et al., 1992) . Since the increase in HR is an important component of physiological adjustm ent of cardiac output (CO) during the intensive growth phase in normal young chickens, adequacy of systemic oxygen ation becom es an important issue in individuals unable to adjust HR during growth. The adequacy of systemic oxygen ation ultim ately depends on the relationship between oxygen demand and oxygen supply. In t...

Ascites and venous carbon dioxide tensions in juvenile chickens of highly selected genotypes and native strains

“…No differences in API values at wk 5 between HRc and LRc groups of D1 birds might be due to a combined effect of a relatively low mean pvCO 2 value in HRc groups at day 12 and fast increasing pvCO 2 values also in LRc groups of D1 during the experimental period. High pvCO 2 and paCO 2 values (50 mm Hg and higher) found in this experiment at wk 4 and 5 were comparable with CO 2 tensions in venous and arterial blood of ascites susceptible modern broiler populations kept at different ambient temperatures (Buys et al, 1999;Korte et al, 1999;Olkowski et al, 1999;Scheele et al, 2003a).…”

“…On the contrary, different experiments at sea level showed that hypercapnia is an evident feature in ascites susceptible broiler populations (Buys et al 1999;Olkowski et al 1999;Scheele et al 2003a). These experiments confirmed results from Reeves et al (1991) who discovered hypoventilation as an important feature in ascites susceptible chickens at sea level.…”

“…Experimental results of Olkowski et al (1999) highlighted that a low cardiac output is the haemodynamic key problem leading to cardiovascular failure in fast growing broilers.…”

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

“…Differences in growth curves between the high-altitude and lowaltitude-grown birds with the concomitant differences on plasma lactic acid levels confirmed earlier findings of Hassanzadeh et al (1999), demonstrating that birds from high altitude are seriously suffering from hypoxia and RVH that could consequently lead to decrease final body weight at the slaughtered age. However, Olkowski et al (1999) and Olkowski and Classen (1998) have published results indicating that RVH and right ventricular failure are secondary to left ventricular failure. This may be brought into relation with changed thyroid function and the lower thyroid hormone levels in postnatal birds when incubated at high altitude because subclinical hypothyroidism causes left ventricle dysfunction, at least in mammals (Fazio et al, 2004).…”

Beneficial effects of alternative lighting schedules on the incidence of ascites and on metabolic parameters of broiler chickens

“…This has greatly reduced the time to reach the desired market weight. However, increased growth rate has been accompanied by a severe incidence of ascites in the commercial broiler industry throughout the world (Olkowski et al, 1999). The ascites syndrome results in significant economic losses to the poultry industry due to mortality, reduced weight gain and increased condemnation at slaughter.…”