Closter A M, van As P, Groenen M A M, Vereijken A L J, van Arendonk J A M, Bovenhuis H
Wageningen University, Animal Breeding and Genomics Centre, 6700 AG Wageningen, the Netherlands.
Poult Sci. 2009 Mar;88(3):483-90. doi: 10.3382/ps.2008-00347.
Ascites, also called pulmonary hypertension syndrome, is a metabolic disorder in chickens that have an insufficient pulmonary vascular capacity. The tendency of broilers to develop ascites is heritable, and successful selection against this susceptibility would benefit from good and easy-to-measure indicator traits. Blood gas parameters have been suggested as indicator traits for ascites susceptibility. Therefore, the aim of the present study was to estimate the heritability of blood gas parameters and the genetic and phenotypic correlations between blood gas parameters, heart ratio (postmortem indicator for ascites), and BW at 2 different ages. For this purpose, blood gas parameters, including the partial pressure of carbon dioxide in venous blood (pvCO(2)), the partial pressure of oxygen in venous blood (pvO(2)), and blood oxygen saturation, were measured at an average age of 22 d in nearly 3,000 broilers. To challenge the resistance of the birds to ascites, they were kept under cold conditions. Heritability for heart ratio was 0.43, and the heritability estimates were low: 0.02 for pvCO(2), 0.03 for pvO(2), and 0.07 for blood oxygen saturation. The estimated heritability for pH was 0.15, for bicarbonate was 0.19, and for total carbon dioxide content was 0.19. The genetic correlations between heart ratio and total carbon dioxide content (0.31 +/- 0.15) and between heart ratio and bicarbonate (0.31 +/- 0.15) were moderate and positive. For pvO(2), the genetic correlation with heart ratio was stronger and negative (-0.62 +/- 0.21); however, this correlation could not be estimated accurately because of the low heritability of pvO(2). For pvCO(2), the genetic correlation with the heart ratio was close to zero (-0.04 +/- 0.45). Phenotypic correlations between traits were, in general, similar to the genetic correlations. Heritabilities for blood gas parameters and the genetic correlations between blood gas parameters and the heart ratio estimated in the present study do not support the suggestion that blood gas parameters measured during wk 3 or 4 are useful traits to select against the susceptibility for ascites.
腹水症，也称为肺动脉高压综合征，是一种在肺血管容量不足的鸡身上出现的代谢紊乱疾病。肉鸡发生腹水症的倾向具有遗传性，而成功筛选抗这种易感性将受益于良好且易于测量的指示性状。血气参数已被提议作为腹水症易感性的指示性状。因此，本研究的目的是估计血气参数的遗传力以及在两个不同年龄时血气参数、心脏比率（腹水症的死后指标）和体重之间的遗传和表型相关性。为此，在近3000只平均年龄为22日龄的肉鸡中测量了血气参数，包括静脉血中二氧化碳分压（pvCO₂）、静脉血中氧分压（pvO₂）和血氧饱和度。为了挑战鸡对腹水症的抵抗力，将它们饲养在寒冷条件下。心脏比率的遗传力为0.43，而血气参数的遗传力估计值较低：pvCO₂为0.02，pvO₂为0.03，血氧饱和度为0.07。pH值的估计遗传力为0.15，碳酸氢盐为0.19，总二氧化碳含量为0.19。心脏比率与总二氧化碳含量（0.31±0.15）以及心脏比率与碳酸氢盐（0.31±0.15）之间的遗传相关性为中度且呈正相关。对于pvO₂，其与心脏比率的遗传相关性更强且为负相关（-0.62±0.21）；然而，由于pvO₂的遗传力较低，这种相关性无法准确估计。对于pvCO₂，其与心脏比率的遗传相关性接近零（-0.04±0.45）。性状之间的表型相关性总体上与遗传相关性相似。本研究中估计的血气参数遗传力以及血气参数与心脏比率之间的遗传相关性并不支持在第3周或第4周测量的血气参数是用于筛选抗腹水症易感性的有用性状这一观点。
