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Abstract
The present study was carried out at the Department of Animal Husbandry and Animal Wealth Development, Faculty of Veterinary Medicine, Alexandria University, throughout the period from March 2009 to August 2010.
The aim of the current study is to estimate the productive and reproductive performances of a random bred population of Japanese quails as well as genetic parameters of growth and reproduction traits of these populations for four generations (the base, first, second and the third).
Studied traits were
1. Body weight was recorded at hatch, 2, 4 and 6 weeks of age for all birds.
2. Relative growth rate
3. Age at sexual maturity (days).
4. Egg production for 45 days after sexual maturity
5. Egg weight for 45 days and egg mass
6. Egg quality (albumen, yolk, shell and shell membrane percentages,
yolk index and haugh unit)
7. Fertility and hatchability percentages
The main results obtained were
I. Phenotypic parameters
1. The average of body weight at hatch; two weeks; four weeks and six weeks were 9.2, 8.7 and 8.7 g; 43.2, 57.1 and 62.9 g; 111.1, 139.4 and 152.3 g; and 186.3, 203 and 214.7g for the first, second and third generation; respectively.
2. Hatch effect showed significant differences among body weight for successive generations as well as sex effect was evident on body weight. Females were heavier than males allover generations. Generation effect was prominent for all studied traits.
3. Age at sexual maturity differed significantly among generations (56.04, 54.38, 49.77, and 45.58 days), for the base, first, second, and third generation; respectively, birds of the third generation reached sexual maturity earlier than those of the base, first, second and the third generations.
4. The overall mean of the first 45 days egg production (HDEP %) for the base, first, second and third generations were 79.80, 88.94, 91.54 and 89.34%; respectively.
5. Egg weights recorded during 45 days of egg production divided into six periods with a week interval ranged from 11.89 to 12.42, 11.70 to 12.59, 12.15 to 12.65, 12.53 to 12.95, 12.44 to 12.91 and 12.41 to 12.98 g for the first, second, third, fourth, fifth and sixth week of the four generations.
6. Means for egg mass recorded of the base, first, second and third generation
were 443.68, 509.41, 524.67 and 494.39g; respectively. High significant difference among generations was found.
7. Fertility percentage ranged from 94.05 to 96.79 % for the four generations and the highest significant percentage was recorded for the first generation, while the lowest was for the second generation. Significant differences among generations were recorded for hatchability percentages. The third generation represented the highest significant percentage (82.3 %), while the lowest was recorded for the second generation (69.7 %).
8. Significant difference recorded among the four generations for albumen percentage 47.00 to 48.42%. Non significant differences between the base and other generations for yolk percentage (37.75, 37.30, 37.26 and 37.28%) for base, first, second and third generation; respectively.
There were significant differences were found among the base, first, second and third generations for shell and shell membrane percentages (15.19, 14.47, 14.91 and 14.32%); respectively.
There were significant differences among the base, first, second and third generations for yolk indices (0.50, 0.50, 0.54 and 0.48); respectively. Haugh unit values ranged from 57.47 to 58.28 for the four generations, the higher significant generation recorded for the second generation and the lower estimate was for the first generation.
II. Genetic parameters
1. Heritability estimates for hatch weight, two weeks, four weeks and six weeks were 0.74 to 0.82, 0.24 to 0.90, 0.16 to 0.30, 0.10 to 0.21; respectively.
2. Heritability estimates of relative growth rate from hatch to two weeks ranged from high to very high 0.46 to 0.91 for the three generations. While those of two to four weeks ranged from moderate to very high 0.20 to 0.91 for the three generations. Heritability for relative growth rate from four week to six weeks ranged from low to very high 0.05 to 0.82 for the three generations. Moreover; heritability estimates for relative growth rate from hatch to the six week body weight ranged from moderate to high 0.23 to 0.38 for the three generations.
3. Age at sexual maturity revealed heritability estimates that ranged from low to high (0.07 to 0.44) for the three generations.
4. Heritability for egg production within 45 days was ranged from low to high (0.13 to 0.44) of the four generations.
5. Heritability for egg weights ranged from 0.19 to 0.89, 0.29 to 0.96, 0.27 to 0.89, 0.27 to 0.91, 0.33 to 0.90 and 0.64 to 0.94 for first, second, third, fourth, fifth and sixth week for the four generations.
6. Heritability for egg mass ranged from 0.27 to 0.44 for the three generations.
7. Heritability for fertility was generally low and ranged from 0.01 to 0.11. In addition, heritability estimates for hatchability percentages ranged from low to moderate (0.06 to 0.16).
8. Heritability for egg quality traits ranged from 0.14 to 0.94, 0.26 to 0.93, 0.24 to 0.95, 0.90 to 0.92 and 0.11 to 0.39 for albumen percentage, yolk percentage, shell and shell membrane percentages, yolk index and haugh unit for the four generations.
9. Phenotypic correlations between hatch weight and other body weights (2nd, 4th, and 6th week) were low and ranged from (0.03 to 0.25), while the corresponding genetic correlation ranged from (-0.02 to 0.53) for the three generations. On the other hand, phenotypic correlation between the 2nd week and those of 4th, 6th week body weight ranged from medium to very high (0.43 to 0.86). The corresponding genetic correlations were medium to very high (0.35 to 0.97) for the three generations. Phenotypic correlations between the 4th and 6th week body weight ranged from (0.53 to 0.65), while the corresponding genetic correlations ranged from (0.61 to 0.86) for the three generations.
10. Phenotypic correlations between age at sexual maturity and the 6th week body weight were -0.34, -0.03 and -0.65 while genetic correlations 0.65, -0.98 and -0.84 for the three generations.
11. Repeatability coefficients for egg production were ranged from 0.10 to 0.21 for the four generations, while repeatability for egg weights were ranged from 0.17 to 0.45 for the four generations
It was concluded that,
• Body weight of Japanese quails could be improved by individual selection for high body weight.
• Improving the environmental conditions can increase the fertility and hatchability percentages.
• Selection for body weight can be applied for two weeks of age due to the high genetic correlation.
• There is confidence in late stages of egg production depending on the repeatability values.