Knowing how energy intake is partitioned between maintenance, growth and egg production (EP) of birds makes it possible to structure models and recommend energy intakes based on differences in the BW, weight gain (WG) and EP on commercial quail farms. This research was a dose-response study to re-evaluate the energy partition for Japanese quails in the EP phase, based on the dilution technique to modify the retained energy (RE) of the birds. A total of 300 VICAMI® Japanese quail, housed in climatic chambers, were used from 16 weeks of age, with averages for BW of 185 g and EP of 78%, for 10 weeks. To modify the RE in the bird’s body, a qualitative dilution of dietary energy was used. Ten treatments (metabolisable energy levels) were distributed in completely randomised units, with six replicates of five quails per experimental unit. Metabolisable energy intake (MEI), egg mass (EM) and RE were expressed in kJ/kg0.67. The utilisation efficiency (kt) was estimated from the relationship between RE and MEI. The metabolisable energy for maintenance was given by RE = 0. The net energy requirement for WG was obtained from the relationship between RE in the BW as a function of the BW. The utilisation efficiency for EP (ko) was obtained from the relationship between EM and RE corrected MEI for maintenance and WG. Based on these efficiencies, the requirements for WG and EM were calculated. The energy intake by Japanese quails was partitioned according to the model: MEI = 569.8 × BW0.67 + 22 × WG + 13 × EM. The current study provides procedures and methods designed for quails as well as a simple and flexible model that can be quickly adopted by technicians and poultry companies.

Egg production performance of 571 local Ghanaian chickens and 107 SASSO T44 chickens kept under improved management conditions were analysed. Average egg weight, hen-day egg production and feed conversion ratio (FCR) were determined for the three experimental chicken ecotypes. Hen-day production was significantly (P < 0.05) higher in the savannah local chicken ecotype than the forest ecotype and SASSO T44 chickens. Egg weights of local Ghanaian chickens compared favourably with values reported for local chickens in Africa. On the average, SASSO T44 had significantly (P < 0.05) higher egg weights and feed intake compared with the local chicken ecotypes. The local chicken ecotypes on the other hand, had significantly (P < 0.05) better feed conversion ratios than SASSO T44 chicken. Local Ghanaian chicken ecotypes have a more efficient FCR per every unit of egg produced compared with the control population. Low feed intake, good feed conversion ratios and adaptation to the environment are traits local chicken harbour which can be exploited in future breeding programmes to improve on chicken meat and egg production in Ghana. Ghanaian local chickens could thus be a valuable genetic resource for the development of an efficient egg production chicken breed adaptable to the humid tropical climates.

Characterization of indigenous animal genetic resources is a first step in providing much needed information for the conservation and utilization of useful genotypes for future needs. The study was undertaken to estimate heritability of traits of economic importance in local chicken populations from the forest and savannah zones of Ghana. A restricted maximum likelihood animal model was applied to growth data of local chickens from hatch to 40 weeks to estimate heritability, phenotypic and genotypic correlations of body weight and shank length. Heritability, phenotypic and genotypic correlations were also calculated for egg number and egg weight. High genetic and phenotypic correlations were obtained between body weight and shank length. Average heritability estimates were 0.54, 0.42, 0.30 and 0.47 for body weight, shank length, egg number and egg weight, respectively. These moderate-to-high heritability estimates indicate that these traits could be targeted in genetic improvement programmes for local chickens.

A review of QTL for production, behaviour and disease resistance traits published to the end of 2004 is presented. QTL were located randomly over the genome and there was little commonality between different studies for similar traits. However, there were several reports of QTL from different experiments in similar regions of chromosomes 1 (at 250 and 450 cM), 4 and 8 and for disease resistance on chromosome 5. Generally there were 6 to 8 QTL affecting the major production traits in experimental breed crosses and collectively they accounted for a substantial proportion of the line difference where this information was provided. The size of typical genome-wide significant effects for production traits was 0.3 to 1.0 phenotypic standard deviations. Genetic effects for growth traits were generally additive whereas about one-third of QTL for other production traits showed significant dominance effects. Variable reporting standards were noted and proposals for minimum published information are presented. Currently there are scientific opportunities for meta-analyses of results from experiments on body weight gain and considerable potential for combining data and results from different studies for other traits in the future.

The physical characteristics of the egg play an important role in the processes of embryo development and successful hatching. The most influential egg parameters are: weight, shell thickness and porosity, shape index, described as maximum breadth to length ratio, and the consistency of the contents. The average values of the physical characteristics mostly meet the requirements for the embryo's development. For those eggs, whose parameters do not fall in to the average range, the incubation process is more successful if the shell is thicker than average, the eggs are more pointed rather than round, and the contents firm. The results reported for investigations into incubating eggs, whose weights are not within the average values, are contradictory. Both thick shells and firm interiors, which are accepted as being higher than average, lead to an increase in egg weight, which probably results in the more successful hatching of embryos from heavier eggs.

Fertility, generally considered as a trait of the two parents, is perhaps best defined as the interaction between the male and female gametes in the production of a viable zygote. Although zygote development and hatchability are traits of the embryo influenced by maternal effects, in most previous studies they have been considered to be female reproductive traits. The aim of this work was to study the influence of sire on fertility and hatchability traits and to estimate the (co)variance components of direct and maternal genetic effects under a Bayesian setting via Gibbs sampling. We measured the fertility of 6396 eggs and the hatchability of 5393 embryos on an individual basis. In addition, egg weight from 42 to 63 weeks of age (EW63) was recorded on an individual egg basis. The sire accounted for a significant amount of the variation infertility and hatchability. For direct heritability, the marginal posterior mean, for fertility and hatchability were almost equal (0·24). The maternal heritabilities for fertility and hatchability were 0·20 and 0·18, respectively. The direct heritability value for the egg weight trait was high. The direct-direct genetic correlation between egg weight and hatchability was negative and significant. The genetic correlations between the direct effect of the egg weight trait and maternal effects for fertility and hatchability were low, with variable signs, and were not significant. On the other hand, significant negative genetic correlations between direct and maternal effects of fertility and hatchability were obtained (the posterior means were –0·56 for FE and –0·55 for HC).

An analysis of data for domestic pullets, turkeys, partridges and quail (Coturnix) indicates that, once all birds within a flock have become sexually photoresponsive but before spontaneous sexual development commences, mean age at first egg, egg production in a given period, mean body weight at first egg and mean egg weight increase linearly with age at photostimulation. These relationships are steeper for age at first egg in turkeys, partridges and quail, for egg production in turkeys and partridges and for egg weight and body weight in turkeys than those seen in domestic pullets. This may indicate differential responses by seasonal and non-seasonal breeding birds, species-specific factors such as geographical origins, or may reflect differing periods of artificial selection in the four species. Egg weight in domestic pullets and turkeys is significantly correlated with body weight at first egg.