|
Lueng Hang Kao Kabinburi (LHKK) is a Thai native dual-purpose chicken breed, which is popular for its meat characteristics. However, LHKK is small in size, ranging in weight from 1 to 1.5 kg at almost four months of age. This study was initiated to explore the genetic control of the growth trajectory of LHKK chicken, using a random regression approach, to improve its body size. Body weights, measured in 11,588 birds from day one (BW1D) to 168 days (BW168D) in 28-days intervals were used to estimate genetic parameters. Model included fixed effects (hatch nested within year, and sex), and random effects (direct additive genetic (DA), direct permanent environmental (DPE), maternal genetic (MG), and maternal permanent environmental (MPE)). The animal ages were fitted as an orthogonal Legendre polynomial covariate. Legendre polynomial of second orders were used for all random effects along with seven classes of residual variances to estimate genetic parameters. Estimated genetic and phenotypic variances increased with increasing age. Heritabilities for DA increased from 0.02 at BW1D to 0.35 at BW168D, and heritabilities for MG decreased after BW1D. Variance ratios for DPE and MPE ranged from 0.01 to 0.40 and from 0.10 to 0.26. Genetic correlations between body weights in 28-days intervals were high, ranging from 0.79 to 1.00 for DA, and from 0.72 to 1.00 for MG. For DPE and MPE, correlations ranging from 0.59 to 1.00 and from 0.00 to 1.00. Phenotypic correlations were high (0.60 to 0.92), except between BW1D and other body weights. The moderate heritabilities and high genetic correlations between subsequent weights indicate that early measures of body weight in LHKK chicken can be used as a selection criterion in order to achieve improved growth rate of LHKK chicken. |
|