Performance and physiological variables in broiler chicken lines differing in susceptibility to the ascites syndrome: 1. Changes in blood gases as a function of ambient temperature

Abstract

1. Male broilers of 5 genetic stocks (A, B, C, D, E) selected in different ways for fast growth and low food conversion ratio (FCR) and differing in ascites sensitivity were subjected to 2 different ambient temperature step down regimens: high temperature (HT: 33 to 20 degrees C over 33 d) and low temperature (LT: 30 to 15 degrees C over 17 d). 2. Ascites incidence was recorded daily. Food intake and body weight gain were measured weekly and FCR was calculated. Heat production (Hp) was calculated using the comparative slaughter method. At 28 d venous samples were taken for blood gas analysis and haematocrit and relative heart, lung and liver weights were recorded. 3. Populations A and C showed the highest growth rates combined with a low FCR and a higher ascites incidence. A low FCR in these stocks was attributable to low values for Hp. These stocks also had low PO2 and high pCO2 in venous blood at low ambient temperature compared with other stocks. Stock B, which exhibited the slowest growth rate and the highest FCR, was not susceptible to ascites and showed higher Hp and PO2 and pCO2 at low ambient temperature. Populations D and E were intermediate for almost all variables. Heart and lung weights were both increased at LT, while liver weight did not differ between temperature regimes. 4. Our results show that a high haematocrit is not necessarily linked with an increased susceptibility to ascites.

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

“…Comparable to the effect of pvCO 2 -risk on pO 2 the results showed that there was no consistent relationship between pvCO 2 and haematocrit values at day 12. These results are in agreement with findings that an increased susceptibility to ascites is not necessarily linked to high haematocrit values (Buys et al, 1999;Scheele et al, 2003b). After day 12, haematocrit values as indicators for hypoxemia increased steadily during ageing in modern breeds but not in ascites resistant breeds.…”

“…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.…”

Ascites Syndrome in Broiler Chickens: A Review on the Aspect of Endogenous and Exogenous Factors Interactions

“…Changes in hematocrit values, partial pressure of oxygen (pO 2 ) and carbon dioxide (pCO 2 ) and endocrine function such as thyroid hormone activity are important regulatory mechanisms of the metabolic rate during the embryonic development and growing period (Buyse et al, 1996;Buys et al, 1998;Decuypere et al, 2000Decuypere et al, , 2005Luger et al, 2001Luger et al, , 2003Teshfam et al, 2005;Arab et al, 2006;Hassanzadeh et al, 2002Hassanzadeh et al, , 2004Hassanzadeh et al, , 2005aHassanzadeh et al, , b, 2008Hassanzadeh et al, , 2010Hassanzadeh et al, , 2012Bahadoran et al, 2010). The role of thyroid hormone in the regulation of metabolism could become more apparent in different genotypes of chickens (Scheele et al, 1992;Scheele, 1996;Decuypere et al, 2000;Luger et al, 2001;Malan et al, 2003;Hassanzadeh et al, 2004Hassanzadeh et al, , 2010 and under environmental conditions such as at low ambient temperature (Scheele et al,1992;Hassanzadeh et al, 2003Hassanzadeh et al, , 2005aHassanzadeh et al, , 2010, different lighting programs (Buyse et al,1994;Buys et al, 1998;Hassanzadeh et al, 2000Hassanzadeh et al, , 2003Hassanzadeh et al, , 2005aHassanzadeh et al, , 2012 and even at high altitudes (Hassanzadeh et al, 2002(Hassanzadeh et al, , 2003(Hassanzadeh et al, , 2004(Hassanzadeh et al, , 2005a(Hassanzadeh et al, , b, 2008.…”

“…The role of thyroid hormone in the regulation of metabolism could become more apparent in different genotypes of chickens (Scheele et al, 1992;Scheele, 1996;Decuypere et al, 2000;Luger et al, 2001;Malan et al, 2003;Hassanzadeh et al, 2004Hassanzadeh et al, , 2010 and under environmental conditions such as at low ambient temperature (Scheele et al,1992;Hassanzadeh et al, 2003Hassanzadeh et al, , 2005aHassanzadeh et al, , 2010, different lighting programs (Buyse et al,1994;Buys et al, 1998;Hassanzadeh et al, 2000Hassanzadeh et al, , 2003Hassanzadeh et al, , 2005aHassanzadeh et al, , 2012 and even at high altitudes (Hassanzadeh et al, 2002(Hassanzadeh et al, , 2003(Hassanzadeh et al, , 2004(Hassanzadeh et al, , 2005a(Hassanzadeh et al, , b, 2008.…”