REPEATABILITY OF BODY WEIGHT AND EGG PRODUCTION TRAITS IN QUAILS UNDER ZARIA ENVIRONMENT
REPEATABILITY OF BODY WEIGHT AND EGG PRODUCTION TRAITS IN QUAILS UNDER ZARIA ENVIRONMENT
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Date
2005-09
Authors
KAYE, JOSHUA
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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.
Description
A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL, AHMADU BELLO
UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF MASTER OF SCIENCE IN ANIMAL SCIENCE (GENETICS &
BREEDING)
DEPARTMENT OF ANIMAL SCIENCE
FACULTY OF AGRICULTURE
AHMADU BELLO UNIVERSITY
P.M.B. 1044, ZARIA
NIGERIA.
Keywords
REPEATABILITY,, BODY WEIGHT,, EGG PRODUCTION,, TRAITS,, QUAILS,, ZARIA ENVIRONMENT