EVALUATION OF PRODUCTION TRAITS IN TWO STRAINS OF LAYER CHICKENS UNDER RELAXED SELECTION
EVALUATION OF PRODUCTION TRAITS IN TWO STRAINS OF LAYER CHICKENS UNDER RELAXED SELECTION
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Date
2013-04
Authors
JOBIN, Jamila
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Abstract
This study was conducted to determine strain differences on some production and egg
quality traits in 200 birds of synthesized Grand Parent Stock (Male and female lines)
under relaxed selection. The hens used were from the same hatch and under the same
management practices. Production traits studied were age at sexual maturity (ASM),
body weight at 18 and 20 weeks of age (BW18 and BW20), egg number (EN), average
egg weight (AEW), and rate of lay (RL). Egg weight (Ewt), egg length (El), egg width
(Ewdt), albumen weight (Albwt), yolk weight (Ywt), shell weight (Swt) albumen height
(Albht), yolk height (Yht), shell thickness (Sth) were measured. Haugh’s unit (HU) and
shell index (SI) were also obtained for egg quality traits. Significant differences (P <
0.05) were obtained for ASM, AEW and BW20 between strains. Male line had higher
mean values in ASM (161.50 days) and AEW (43.66g) but Female line had better mean
value for ASM (158.79days). For egg quality traits, significant (P < 0.05) differences
were also observed in Ewt, El, Ywt, Swt and HU. Higher mean values were obtained for
all traits (Ewt, El, Ywt, and Swt) with the exception of HU in the Female line than the
Male line. Pearson correlation pooled for growth and egg production traits for the two
strains showed that ASM had moderate to high negative and significant (P < 0.01)
relationship with EN, BW18 and BW20. ASM was also positively correlated with RL
and AEW. There was a positive and highly significant (P < 0.01) relationship between
EN with RL, BW18 and BW20. while AEW had no significant (P > 0.05) relationship
with all other traits. BW18 and BW20 had the highest level of correlation (0.87) which
was positive and highly significant. It can be concluded that, the female line had better
performance than the male line in ASM (158.79 vs 161.50 days), BW18 (1176.87 g vs
1171.62 g) and BW20 (1370.17 g vs 1327.39 g). Coefficients of variation within strains
for most studied traits were higher than 20%. The phenotypic correlations among
studied traits vary in magnitude and direction implying stability of the traits in both
strains under relaxed selection. Since the coefficient of variation of most of the studied
traits within the individual strains had values higher than 20% it is therefore
recommended that selection can still be resumed and appreciable response to selection
can be obtained
Description
A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL,
AHMADU BELLO UNIVERSITY, ZARIA NIGERIA
IN PARTIAL FULFILMENT FOR THE AWARD OF MASTERS OF SCIENCE IN
ANIMAL SCIENCE
DEPARTMENT OF ANIMAL SCIENCE
FACULTY OF AGRICULTURE
AHMADU BELLO UNIVERSITY
ZARIA
APRIL, 2013