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This study aims to contribute towards the genetic improvement of Nigerian local chicken ecotype through selection. Genetic parameters for body weight at first egg (BWFE), egg number (EN) and egg weight (EW) till first 90 days of lay were estimated for both selected and control lines. Selection was based on an index using BWFE, EN and EW as the selection criterion traits. After three generations of index selection, BWFE, EN and EW all improved significantly (P<0.05) in the selected line. The heritability estimates for all traits in the three generations for both lines were moderate to high (BWFE, EN, EW,). Low to high positive genetic and phenotypic correlation was observed between BWFE and EW. The genetic and phenotypic correlation between BWFE and EN, and EW and EN were generally moderate to highly negative in both lines for all generations. However, in the second generation of the selected line a positive genetic correlation (0.33) was observed between EW and EN.

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IntroductionResearch findings indicate that less productive local breeds of livestock and poultry can be of commercial and breeding utility if crossed with improved strains (ABDOU and KOLSTAD 1984; ASUQUO 1984;CONSTANTINOU 1985;Nwosu and OMEJE 1984;Nwosu et al. 1985). Not only have the local breeds and their crosses been reported to exhibit appreciable performance in production traits, they have been shown to generate several crossbred populations of different genetic merit. They widen existing genetic bases which are important for selective breeding. In difficult situations such as in Nigeria and other less developed countries, selection of crossbred populations seems to be a solution where exotic parental lines used to produce commercial stocks have plateaued from constant selection, and when alternative lines of the same breeds are not available and cannot be replaced.This paper is a pre-selection evaluation of crossbred chicken lines generated from the matings between the local chicken of Nigeria and an exotic "Gold-link" parent stock strain. The study was necessitated by the need to have information on the level of heterosis in the F1, and that of the residual heterotic effects in the Fz, backcross and subsequent generations before starting a meaningful trait-group selection on crossbred populations. The data so obtained will provide further information as to the mode of action of factors controlling the heterotic traits without which knowledge any selection on such populations could be misguided. Materials and methodsThe experiment was carried out with a total of 3,076 birds from different populations established as follows: Parental and F1 populationsThe gold-link (Pl) exotic and local chicken (P2) base populations, comprising 572 and 489 birds respectively, were established at the same time in February 1981 in the Poultry Unit of the University of Nigeria Teaching and Research Farm at Nsukka where the study was undertaken. The indigenous birds were derived from eggs obtained from interior villages of the Eastern states of Nigeria, while day-old chicks of the gold-link B72 parent stock strain were ordered from Pennsylvania, U.S.A. The base population chicks were raised on deeplitter floors under standard management procedures and crossed at maturity to produce 1370 parental and F1 crossbred progeny chicks which were brooded and reared in the same manner as their parents. U.S.