%K Egg size Embryo mortality Fertility rate Hatchability Koekoek breed chickens %J Online Journal of Animal and Feed Research %A S. Molapo %A M. Motselisi %V 10 %L eprints46 %D 2020 %N 6 %R 10.51227/ojafr.2020.37 %X The aim of this study was to determine the effect of egg size on egg shell, egg yolk, fertility rate and hatchability of Koekoek chickens. A Complete Randomized Design (CRD) was used with egg size being the treatment factor. The treatments were large (>55g), medium (45-54g) and small (<44g) sized eggs. Eggs were collected from the nests and weighed using the digital scale and classified according to their respective weights before incubation. The egg yolk weight was measured with the digital scale. The shell thickness was measured using a Vanier caliper. The fertile and infertile eggs were identified. The fertility rate, hatching percentage and embryonic mortality were recorded. Data collected was subjected to statistical analysis by using one way analysis of variance (ANOVA). The medium sized eggs had higher fertility and hatchability percentage compared to large and small sized eggs. The mortality was higher in large and small sized eggs. Therefore, select eggs at the range of 45 to 55 grammes for incubation can be useful to increasing hatchability. © 2020, Online Journal of Animal and Feed Research. All Rights Reserved %P 278-281 %I Scienceline Publication %T THE EFFECT OF EGG SIZE (WEIGHT) ON THE EGG SHELL THICKNESS, EGG YOLK AND HATCHABILITY IN KOEKOEK CHICKENS