Thesis 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 forthis study aimed at improving egg production traits in the LLCE using a selection index. Thehens were monitored for short-term (90-days from first day of lay) egg production traitsnamely Body Weight at First Egg (BWFE), Average Egg Weight (AEW) and Total EggNumber (TEN). Data obtained were subjected to statistical analysis using SPSS (2001) andpaternal half-sib model with Harvey (1990) to estimate descriptive statistics and geneticparameters respectively. These were employed in constructing the selection index. Selectionfor all the selection criteria (BWFE, AEW and TEN) was in the positive direction. Selectedparents were mated to produce next generations – G1 and G2. Selection differentials,selection intensities and genetic response due to selection were also estimated. A controlpopulation which spanned for three generations (each generation had its own controlpopulation) 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 theselected 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 allgenerations and populations were moderate to high. The heritability of the index was alsomoderate. Such moderate to high heritability estimates indicate high additive geneticvariances, 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 andAEW in all populations of study. The genetic correlation and phenotypic correlation betweenBWFE and EN, and between AEW and EN, was moderate to highly negative for allgenerations and populations of study. A positive genetic correlation was observed betweenAEW and TEN in G2 of the selected population. A cumulative selection differential of269.38g, 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.

Thesis Overview