Genetic parameters for blood oxygen saturation, body weight and breast conformation in 4 meat-type chicken lines.

Roslin Institute, Roslin, Midlothian EH25 9PS, Scotland, UK.
British Poultry Science (Impact Factor: 0.78). 01/2007; 47(6):659-70. DOI: 10.1080/00071660601042372
Source: PubMed

ABSTRACT 1. The objective of the study was to explore the genetic architecture of blood oxygen saturation (SaO) (an indicator trait, negatively correlated with ascites susceptibility), body weight (Weight) and fleshing score (Flesh, a measure of breast conformation) for 4 meat-type chicken lines reared in commercial conditions. 2. Genetic components, including heritabilities and genetic correlations, were estimated by Restricted Maximum likelihood for these traits measured at 6 weeks of age. 3. Data were collected over eight generations of selection and pedigrees comprised in excess of 130,000 birds. 4. Univariate analyses were performed to allow model definition and to obtain starting values for trivariate analyses. The basic model included a random animal effect and, in further models explored, a maternal environmental effect or a genetic maternal effect or both were fitted. Models were compared using likelihood ratio tests. 5. Estimated heritabilities for SaO ranged from 0.1 to 0.2, and there was no evidence of genetic maternal effects for SaO. The environmental maternal component was significant for one of the populations only. Estimated heritabilities for both Weight and Flesh were between 0.2 and 0.4, and there was evidence of environmental and genetic maternal effects for these traits in all populations. 6. Genetic correlations between SaO and Weight and between SaO and Flesh were low and negative. This suggests that, in principle, genetic selection to simultaneously increase SaO, and therefore decrease ascites susceptibility, and WEight and Flesh could be performed using traditional (marker-free) selection methods. We discuss how a putative interaction between ascites and production traits could jeopardise the success of such methods.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The present study aimed to investigate the effects of maternal factors on body weight at hatching (day-old) and at six weeks of age in a commercial broiler line. A total of 6,765 records on body weight at day-old (BWTDO) and 115,421 records on body weight at six weeks of age (BWT6W), originated from a commercial broiler line during 14 generations, were used to estimate genetic parameters related to the effects of maternal traits on body weight of chicks immediately after hatch or six weeks thereafter. The data were analyzed using restricted maximum likelihood procedure (REML) and an animal model with DFREML software. Direct heritability (), maternal heritability (), and maternal environmental variance as the proportions of phenotypic variance () for body weight at day-old were estimated to be 0.050, 0.351, and 0.173, respectively. The respective estimated values for body weight at six weeks of age were 0.340, 0.022, and 0.030. The correlation coefficient between direct and maternal genetic effects for six-week-old body weight was found to be -0.335. Covariance components and genetic correlations were estimated using a bivariate analysis based on the best model determined by a univariate analysis. Between weights at hatching and at six week-old, the values of -0.07, 0.53 and 0.47 were found for the direct additive genetic variance, maternal additive genetic variance and permanent maternal environmental variance, respectively. The estimated correlation between direct additive genetic effect influencing weight at hatch and direct additive maternal effect affecting weight at six weeks of age was -0.21, whereas the correlation value of 0.15 was estimated between direct additive maternal effect influencing weight at hatch and direct additive genetic effect affecting weight at six-week-old. From the present findings, it can be concluded that the maternal additive genetic effect observed for weight at six weeks of age might be a factor transferred from genes influencing weight at hatch to weight at six-week-old.
    Asian Australasian Journal of Animal Sciences 03/2010; 23(3). DOI:10.5713/ajas.2010.90325 · 0.56 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose. To investigate the extent to which shared genetic variants control (1) multiple ocular component dimensions and (2) both normal eye length and susceptibility to visually induced myopic eye growth. Methods. Two laboratory-reared populations of chicks were examined. The first was a three-generation pedigree of White Leghorn (WL) birds used in a selective breeding experiment testing susceptibility to monocular deprivation of sharp vision (DSV). The chicks were assessed before (age, 4 days) and after 4 days of treatment with diffusers. The second was the 10th generation of an advanced intercross line (AIL) derived from a broiler-layer cross (age, 3 weeks). Variance components analysis was used to estimate heritability and to assess the evidence for shared genetic determination. Results. All measured ocular components were moderately or highly heritable (range, 0.36-0.61; all P < 0.001) in both chick populations, and there were strong genetic correlations across the traits, corneal curvature, vitreous chamber depth, and axial length. The genetic correlations between eye size and myopia susceptibility traits were not significantly different from 0. Conclusions. The genetic variants controlling ocular component dimensions in chicks are shared across some ocular traits (corneal curvature, vitreous chamber depth, and axial length) but distinct for others (lens thickness and corneal thickness). The genetic variants controlling susceptibility to visually induced myopia in chicks are different from those controlling normal eye size.
    Investigative ophthalmology & visual science 03/2011; 52(7):4012-20. DOI:10.1167/iovs.10-7045 · 3.66 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In order to investigate the relationship between carbon dioxide tensions in the venous blood of young chickens and ascites susceptibility, one hundred day-old 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 slow-growing (line B) chickens, confirming that line A chickens had higher susceptibility to ascites than line B chickens. At 12 days of age, the mean pCO(2) 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 pCO(2) 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.
    Acta Veterinaria Hungarica 06/2010; 58(2):221-30. DOI:10.1556/AVet.58.2010.2.8 · 0.80 Impact Factor

Full-text (2 Sources)

Available from
Jul 7, 2014