Haematological characteristics predicting susceptibility for ascites. 1. High carbon dioxide tensions in juvenile chickens
article
1. Male broilers of two different genetic stocks, a pure broiler sire line (A) and commercially available Ross broilers (B), were used to study the effect of haematological characteristics in juvenile chickens on the development of clinical ascitic signs. Production performance (body weight gain (BWG), feed intake (FI), feed conversion ratio (FCR)) from 448 birds per stock was measured from 2 to 5 weeks of age. Mortality was recorded from 2 to 6 weeks of age. The birds were housed at a low ambient temperature to stimulate the incidence of ascites. 2. From each stock, 32 birds with the highest (high risk: HR <sub>c</sub>) and 32 birds with the lowest (low risk: LR<sub>c</sub>) carbon dioxide tensions (pCO<sub>2</sub>) in venous blood were selected at 11 d of age. These birds were marked for future blood sampling to determine changes in pCO<sub>2</sub> with age to relate these values to ascites susceptibility. 3. At 2 weeks of age all birds (including HR<sub>c</sub> and LR<sub>c</sub> birds) were allotted to 32 floor pens (one HR<sub>c</sub> and one LR<sub>c</sub> in each pen) per stock. Venous blood samples were collected weekly from HR <sub>c</sub> and LR<sub>c</sub> birds for blood gas analysis and haematocrit, and at week 5 also for thyroid hormone (T3, T4) concentrations in plasma. At 5 weeks of age all HR<sub>c</sub> and LR<sub>c</sub> birds were examined post-mortem, relative heart, lung, and liver weights and arterial pressure index (API) values were recorded. 4. Birds from stock A showed a lower BWG and FCR and notably higher ascites mortality compared with stock B. An effect of pCO<sub>2</sub> tensions at d 11 was found on the incidence of ascitic signs in selected birds of both stocks up to week 5. From the HR<sub>c</sub> groups 30% of the birds showed ascitic signs, whereas this was only 8% in the LR <sub>c</sub> group. LR<sub>c</sub> birds of stock B in particular showed constant low API values (20 ± 3%) and none of these birds showed signs of ascites. 5. Our results suggest that the ascites problem in Ross birds can be eliminated by selection for pCO<sub>2</sub> tensions in venous blood. Stock effects on API, liver weight, lung weight, and plasma thyroid hormone independent of pCO<sub>2</sub> showed a more complex picture of the ascitic signs in stock A compared with B. 6. We concluded that in this experiment a high pCO<sub>2</sub> tension in venous blood measured at d 11 was a reliable predictor for ascites susceptibility observed at 5 weeks of age. A low pCO <sub>2</sub> tension provides an appropriate criterion for genetic selection, whereas a high pCO<sub>2</sub> tension emphasises the necessity for intensive management in poultry houses. Chemicals/CAS: carbon dioxide, 124-38-9, 58561-67-4; Carbon Dioxide, 124-38-9; Thyroid Hormones
Topics
carbon dioxidethyroid hormoneanimalanimal diseasearticleascitesbird diseasebloodblood gas analysischickengenetic predispositiongeneticsgrowth, development and aginghematocritincidencemalemetabolismorgan sizepathophysiologyrandomizationtemperatureweight gainAnimalsAscitesBlood Gas AnalysisCarbon DioxideChickensGenetic Predisposition to DiseaseHematocritIncidenceMaleOrgan SizePoultry DiseasesRandom AllocationTemperatureThyroid HormonesWeight GainAnimaliaAvesGallus gallus
TNO Identifier
280270
ISSN
00071668
Source
British Poultry Science, 44(3), pp. 476-483.
Pages
476-483
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