Turkish Journal of Veterinary & Animal Sciences




The aim of this study was to estimate the heritability values of tonic immobility duration, several growth traits, and their genetic relationships with some slaughter traits. Fearfulness reaction was examined using tonic immobility (TI) response at 5 and 6 weeks of age. All birds were slaughtered at 6 weeks of age to measure carcass yield (CY), and percentage of breast (BY), leg (LY), wing (WY), abdominal fat (AFY). Heritability estimates for the TI durations and body weights measured at 5 and 6 weeks of age were 0.16, 0.20, and 0.46, 0.44, respectively. Heritability estimates for growth curve parameters and inflection point coordinates of Gompertz model were moderate to high, with values ranging from 0.36 to 0.54. Low heritability estimates for CY, BY, LY, and WY were found as 0.17, 0.19, 0.19, and 0.12, respectively. Genetic and phenotypic correlations between TI and BW-growth traits were determined low and statistically nonsignificant (P > 0.05). Similarly, genetic and phenotypic relationships between TI and carcass yield, and between TI and percentages of carcass parts were found low and statistically nonsignificant (P > 0.05). As a result, it is possible to say that applying multitrait selection including TI trait will not affect other yield characteristics.


Tonic immobility, heritability, genetic correlation, carcass yield, abdominal fat

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