ABSTRACT
Fifty hens and five cocks from a random mating population of
light local chicken ecotype
(LLCE) were mated and the fertile eggs hatched to obtain the
parent generation (G0) used for
this study aimed at improving egg production traits in the
LLCE using a selection index. The
hens were monitored for short-term (90-days from first day
of lay) egg production traits
namely: Body Weight at First Egg (BWFE), Average Egg Weight
(AEW) and Total Egg
Number (TEN). Data obtained were subjected to statistical
analysis using SPSS (2001) and
paternal half-sib model with Harvey (1990) to estimate descriptive
statistics and genetic
parameters respectively. These were employed in constructing
the selection index. Selection
for all the selection criteria (BWFE, AEW and TEN) was in
the positive direction. Selected
parents were mated to produce next generations – G1 and G2.
Selection differentials,
selection intensities and genetic response due to selection
were also estimated. A control
population which spanned for three generations (each
generation had its own control
population) was used to monitor environmental changes and to
estimate the genetic changes
due to selection.
There were significant increases (P<0.05) in BWFE, AEW,
and TEN in the
selected populations over the three generations of study
such significant increases (P<0.05)
were not observed in the control population. Heritability
estimates for all traits in all
generations and populations were moderate to high. The
heritability of the index was also
moderate. Such moderate to high heritability estimates indicate
high additive genetic
variances, implying that these traits were most passed on
from the parents to their offspring.
Low to high positive genetic and phenotypic correlations was
observed between BWFE and
AEW in all populations of study. The genetic correlation and
phenotypic correlation between
BWFE and EN, and between AEW and EN, was moderate to highly
negative for all
generations and populations of study. A positive genetic
correlation was observed between
AEW and TEN in G2 of the selected population. A cumulative
selection differential of
269.38g, 1.58g and 3.88 eggs were obtained for BWFE, AEW and
TEN respectively.
Selection response for traits increased over the generations
in a fairly linear manner.
Realized response per generation was estimated to be 94.22g,
0.84g and 4.85eggs for BWFE,
AEW and TEN respectively. It is evident that the
simultaneous inclusion of BWFE, AEW,
and TEN in a selection index generally improved the
performance of selected birds over the
generations in the Light Local Chicken Ecotype.