No abstract

This study was carried out to identify the white plumage in Japanese quail and compare it with the brown-type quail for possible genetic and phenotypic differences associated with the plumage colour, estimate the genetic and phenotypic correlation coefficients between both body weight (BW) and shank length (SL) at different ages from hatch up to 35 days of age based on weekly intervals and the age at the first egg (AFE), number of days needed to produce the first 10 eggs (DN 10 ), number of days needed to produce the first 30 eggs (DN 30 ), age at first 10 eggs (AGE 10 ), age at first 30 eggs (AGE 30 ), egg mass of the first 10 eggs (EM 10 ), egg mass of the first 30 eggs (EM 30 ), number of eggs produced in the first month (EN FM ), number of eggs produced in the second month (EN SM ), number of eggs produced in the first two months (ENF TM ), egg mass for the first month (EM FM ), egg mass for the second month (EM SM ) and egg mass of the first two months (EM FTM ) which individually recorded by bird.The main results are summarized as the following:1-The brown genotype had significantly heavier BW at the ages 21, 28, 35 day and at sexual maturity, where longer SL at 7 and 21 day of age than the white genotype. The white genotype had significantly heavier BW at one day old than the brown genotype.2-The brown genotype matured at earlier age than the white genotype (P≤0.05) by 6.08 days. However, the white genotype had longer days that needed to produce the first 30 eggs(P≤0.05) by 8.66 days and attained the first 10 and 30 eggs at later ages (27.32 and 38.34 days of age) than the brown genotype.The brown genotype showed numerically higher estimates(P≥0.05) for DN 10 , EM 10 , EM 30 , EN FM , EN FTM , EM FM , EM SM and EM FTM than the white genotype.In conclusion, the results of the present study indicated that there were significant differences between the two genotypes, brown and white in the phenotypic and genetic parameters of most studied traits favoring significantly the brown quail for growth traits except BW1 and numerically egg production-related traits (DN 10 , EM 10 , EM 30 , EN FM , EN FTM , EM FM , EM SM and EM FTM) than the white quail that could be used in breeding programs to improve these genotypes.

The present investigation was carried out to estimate the effects of genotype and sex on growth and laying performance and assess the variations in plasma constituents in the tested genotypes and their relations with productive traits after four generations of selection. Data of growth and laying performance on 1440 females and males of Japanese quail were taken from the three quail genotypes: maternal (MG), long shank length (LSG28) and control (CG) genotypes. Genotype significantly affected all studied growth productive traits, favouring selected genotypes. The LSG28surpassed MG in total protein, albumin (Alb), globulin (Glob), triglycerides and Alb/Glob ratio and lowered both cholesterol and total lipids (TL). Sex significantly favoured females, which had higher body weight, longer shank length at 35 days of age and higher body weight gain during the period from 1 to 35 days of age. Females showed significantly higher concentrations of both Alb and TL than males. The MG exceeded LSG28in fertility and hatchability per cent. Correlations for both growth and productive traits with plasma constituents revealed inconsistent trends in either magnitude or direction. Four generations of selection resulted in substantial phenotypic improvements in most growth and productive traits, as well as plasma constituents studied in LSG28, and favoured MG in maturity, days needed to produce the first ten eggs, higher egg production per cent and heavier egg mass.

The main objectives of this study were to detect the most appropriate random regression model (RRM) to fit the data of monthly egg production in 2 lines (selected and control) of Japanese quail and to test the consistency of different criteria of model choice. Data from 1,200 female Japanese quails for the first 5 months of egg production from 4 consecutive generations of an egg line selected for egg production in the first month (EP1) was analyzed. Eight RRMs with different orders of Legendre polynomials were compared to determine the proper model for analysis. All criteria of model choice suggested that the adequate model included the second-order Legendre polynomials for fixed effects, and the third-order for additive genetic effects and permanent environmental effects. Predictive ability of the best model was the highest among all models (ρ = 0.987). According to the best model fitted to the data, estimates of heritability were relatively low to moderate (0.10 to 0.17) showed a descending pattern from the first to the fifth month of production. A similar pattern was observed for permanent environmental effects with greater estimates in the first (0.36) and second (0.23) months of production than heritability estimates. Genetic correlations between separate production periods were higher (0.18 to 0.93) than their phenotypic counterparts (0.15 to 0.87). The superiority of the selected line over the control was observed through significant (P < 0.05) linear contrast estimates. Significant (P < 0.05) estimates of covariate effect (age at sexual maturity) showed a decreased pattern with greater impact on egg production in earlier ages (first and second months) than later ones. A methodology based on random regression animal models can be recommended for genetic evaluation of egg production in Japanese quail.

Glutathione peroxidase (GSHPx) activity was investigated in the liver, red blood cells (RBC) and blood plasma (BP) of different chicken genotypes. Signifi cant differences among genotypes and age groups were found in liver GSHPx activity during embryonic development and in day-old chickens. Breed, sex and age effects were found in RBC and BP from one day of age until peak egg production. A negative correlation was found between embryo liver GSHPx activity and egg weight (-0.24; P≤0.01), between RBC and BP GSHPx activity and body weight (-0.32 and -0.44; P≤0.01), and between liver and RBC GSHPx activity (-0.54; P≤0.01), while positive correlations were demonstrated between liver and BP (0.66; P≤0.01) and BP and RBC (0.32; P≤0.01) GSHPx activity. In conclusion, variation in GSHPx activities in different chicken breeds during development suggests that it is genetically regulated. This fi nding indicates that GSHPx activity may be useful in selection.