Genetic Change in the Nigerian Heavy Local Chicken Ecotype Through Selection for Body Weight and Egg Production Traits

Abstract:

The study was carried out to determine the genetic change in the Nigerian heavy local chicken ecotype (NHLCE) through selection for body weight and egg production traits. Progenies (G0 generation) generated from breeding parents randomly selected from the parent stock of the NHLCE formed the materials for the research. On hatching, the chicks were grouped according to sire families using colour markers. The chicks were brooded and reared according to standard management practices. They were fed a starter mash containing 18% crude protein and 2800 Kcal/kgME from 0 – 8 weeks and a growers mash containing 15% crude protein and 2670 Kcal/ kgME from 8 weeks to 20 weeks. At 20 weeks, all pullets were moved into individual laying cages for short-term (16 weeks) egg production. From then the birds were fed layers mash containing 16.5% crude protein and 2600Kcal/kgME. Data were collected on body weight, egg weight and egg number. A control population was maintained for each generation and was used to measure environmental effects. At the end of the 16 weeks egg production period, hens were subjected to selection using a multiple trait selection index incorporating body weight at first egg (BWFE), average egg weight and total egg number. The relative economic weights of the traits and their heritabilities were used to weight the phenotypic values of each trait in the index. The index score of each bird became a univariate character, which enabled the hens to be ranked for purposes of selection. Males were selected based on their individual body weight performances at 39 weeks of age using mass selection. Selected parents from G0 generation were used to generate the G1 generation which in turn yielded the parents of the G2 generation. Data on body weight, BWFE, egg weight and egg number were subjected to statistical analysis to obtain means, standard error of means and standard deviation using the SPSS 2001 statistical package. Analysis of variance yielded sire component of variance from which the additive genetic heritabilities of the traits were calculated. Genetic, phenotypic and environmental correlations between pairs of traits in the index were estimated. Indicators of selection response, namely, selection differential, expected, predicted and realized genetic gains were determined for each trait. There were significant increases....