SHORT-TERM SELECTION FOR BODY WEIGHT AND GROWTH RATE IN JAPANESE QUAIL 1. DIRECT SELECTION RESPONSE | ||||
| Fayoum Journal of Agricultural Research and Development | ||||
| Article 19, Volume 20, Issue 2, July 2006, Page 227-241 PDF (553.5 K) | ||||
| Document Type: Research articles. | ||||
| DOI: 10.21608/fjard.2006.197604 | ||||
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| Authors | ||||
| Gihan. S. Farahat1; Ensaf. A. El Full1; Mohamed H. Abdel Fattah2; Nabel, A. Hataba2; M. A. Khalifa1 | ||||
| 1Poultry Production Dept., Faculty of Agriculture, Fayoum Univ., Egypt. | ||||
| 2Animal Production Research Institute, ARC, Dokki, Egypt. | ||||
| Abstract | ||||
| Three quail lines were used in this work to study the effects of mass selection for increased body weight or growth rate: HBW42 line was selected for high body weight at 42 day of age, HGR1-42 line was selected for high growth rate during the period from one-day to 42 day of age and randombred control line (RBC) was maintained as non-selected pedigreed population over three generations of selection. The following results were obtained: There was an asymmetry in the direct response to selection in the male and female BW and GR favoring females. After three generations of mass selection, the HBW42 line exceeded the RBC by 8.40g (4.81%) and 13.66g (7.53%) for males and females, respectively. The regression coefficients were higher for females than males after the 3rd generation being 2.28g (1.295%) for females vs 0.475 g (0.315%) for males than the RBC. After three generations of mass selection, GR1-42 line decreased from 184.1 to 183.8% for males and 184.9 to 184.2% for females. Females had significantly higher response on generation number either as a deviation or as a percent deviation from the controls. The ratios of effective to the realized selection differentials for the selected lines and sex groups were more than unity, except for females in the 1st generation of selection for HGR1-42 line which was indicating that natural selection for fitness did operate in the opposite direction of artificial selection. The more than unity ratios in all sex groups of the HBW42 line and males of HGR1-42 line indicated that natural selection did not affect artificial selection. Selection yielded, with few exceptions, consistently lower heritability estimates in the selected lines, regardless of the estimation method. The unweighted mean of heritability estimates either for male or female progeny weights indicated that non-additive, primarily and maternal effects may be affected body weights. The larger h2S for females of HGR1-42 line in the 2nd and 3rd generations of selection than h2D indicated sex-linked effects. Females had considerably higher realized heritabilities than males. The realized heritabilities obtained for the HGR1-42 line were generally higher than those for the HBW42 line (0.69 vs 0.41). Generally, as generation number increased realized heritabilities for the selected traits in all sex groups decreased. The rate of decline in magnitude of heritabilities was higher in the HGR1-42 line than the HBW42 line. Whereas, the heritabilities of all sex groups for the RBC were higher than those for the selected lines. It can be concluded that the direct response for HBW42 line was greater than those of the line selected for HGR1-42 compared to their controls. | ||||
| Keywords | ||||
| Short-term; selection; direct response; body weight; growth rate; Japanese quail | ||||
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