REPEATABILITY OF BODY WEIGHT AND EGG PRODUCTION TRAITS IN QUAILS UNDER ZARIA ENVIRONMENT

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REPEATABILITY OF BODY WEIGHT AND EGG PRODUCTION TRAITS IN QUAILS UNDER ZARIA ENVIRONMENT

Abstract:

Forty-eight Japanese quail (Coturnix coturnix japonica) hens were individually caged and intensively reared for a period of 28 weeks to study the egg production pattern, egg quality characteristics and the relationships between laying age and repeatability of egg quality characteristics. The results shows that the 165 days egg production characteristics of the birds were, egg number 103 + 15, number of clutches 38+6, clutch size 3.0 +1.0, number of pauses 38 + 4, days pause 54 + 14 and pause length 2.0 + 1.0 days Significant (P<0.05) and positive relationship existed between egg number and clutch size (r=0.85) which was negatively related with number of clutches, number of pauses, days paused and pause length (r = -0.46 to -0.72). Age of quail hens significantly (P<0.01 – 0.05) influenced the measured characteristics, except albumen height, yolk width, albumen weight and shell membrane thickness, respectively. Body weight, egg weight and egg breadth increased with increase in age of the quail hens from 12 to 28 weeks while albumen index and haugh unit were decreased within the same period. Quadratic function was a better estimator of the relationships of age, body weight and egg weight with the egg quality traits than linear function. Repeatability estimates for body weight and egg traits ranges from 0.58 to 0.99 for 12 and 28 weeks, respectively. Repeatability of egg length, yolk plus albumen weight, egg index and shape index showed a linear relationship with age, where as the remaining traits showed a curvilinear relationship with age. The general increase in repeatability of each trait with age indicates that fewer records would be required to adequately characterize the inherent producing ability of each hen for the trait as laying age progressed. At the age of 28 weeks old the pullets attained maximum efficiency in repeatability estimates. This study has shown that Japanese quails attain a peak production of 86% at 12 weeks (84 days) of age. Egg number increased with clutch size but decreased with number of clutches, number of pauses, days paused and pause length. The expected relative genetic gain per generation of selection for repeated records was inversely related to the magnitude of repeatability. Thus, as laying progressed, repeatability estimates became higher and the expected genetic gain from using additional records decreased and fewer records were required to characterize the pullets for inherent transmitting ability. Four eggs per hen are considered adequate for 12-week egg weight, egg length, egg breadth, albumen width, albumen height, yolk width, yolk height, yolk plus albumen weight, yolk weight, albumen weight, shell + membrane weight, shell plus membrane thickness, shell thickness, shell membrane thickness and haugh unit, 8 eggs are required for albumen index, yolk index, egg index and shape index. The number of eggs for corresponding traits at 28 weeks is 3 or 4. In conclusion, the egg quality characteristics were modified as the quail hens aged and the best criterion for judging the shell strength was the egg shape.

REPEATABILITY OF BODY WEIGHT AND EGG PRODUCTION TRAITS IN QUAILS UNDER ZARIA ENVIRONMENT

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