PARTIAL PRESSURE OF CARBON DIOXIDE IN THE VENOUS BLOOD OF YOUNG BIRDS AS A PREDICTOR OF ASCITES SUSCEPTIBILITY IN BROILER CHICKENS

Acta Veterinaria Hungarica 58 (2), pp. 221–230 (2010)
DOI: 10.1556/AVet.58.2010.2.8



Mohammad HASSANZADEH1*, M. S. MADADI2, S. MIRZAIE1, K. ASSASIE3
and H. MOAYYEDIAN3
1Department of Clinical Science, Faculty of Veterinary Medicine, University of Tehran,


P.O. Box 14155-6453, Tehran, Iran; 2Department of Clinical Science, Faculty
of Veterinary Medicine, University of Tabrize, Tabrize, Iran; 3Department of Clinical
Science, Faculty of Veterinary Medicine, University of Shiraz, Shiraz, Iran
(Received 11 May 2009; accepted 23 September 2009)


In order to investigate the relationship between carbon dioxide tensions in
the venous blood of young chickens and ascites susceptibility, one hundred dayold
chickens from two pure broiler breeder lines differing in susceptibility to ascites
syndrome were obtained and reared at low environmental temperature.
Weekly, blood samples were taken for the determination of blood gas parameters
and plasma thyroid hormone levels. Dead birds were examined for lesions of ascites
daily and all survived birds were autopsied at the end of the trials. In cold
conditioning, the cumulative incidence of right ventricular hypertrophy (RVH)
and ascites was 78% (39/50) in fast-growing (line A) and 50% (25/50) in slowgrowing
(line B) chickens, confirming that line A chickens had higher susceptibility
to ascites than line B chickens. At 12 days of age, the mean pCO2 tension was
significantly (P<0.01) higher in the venous blood of line A than line B chickens.
During the experiment, the majority of line A and line B chickens showing RVH
and ascites exhibited pCO2 tensions equal to, or exceeding 50 mmHg at 12 days of
age. Additionally, fast-growing chickens showed significantly lower plasma T3
and T4 concentrations than slow-growing chickens. In conclusion, our data indicate
that carbon dioxide pressure in the venous blood of early postnatal broiler
chickens could be used as a valuable predictor in the selection of birds susceptible
to pulmonary hypertension and ascites. The function of thyroid hormones should
also be taken into consideration in further selection procedures for meat-type
chickens.
Key words: Ascites, broiler chicken, carbon dioxide, thyroid hormones