Phenotypic and genetic characterization of indigenous chicken populations in Northwest Ethiopia

[摘要] English: This study was carried out to generate information on village based indigenous chicken utilization, management practices, opportunities and challenges, to identify, characterize and describe the phenotypic variation of indigenous chicken populations. The study was also aimed to provide preliminary data on the genetic variation of indigenous chicken populations using microsatellite markers and to compare and evaluate the growth, egg production, reproductive performances, as well as the rate of survival of indigenous chickens under intensive and extensive management levels. Surveys using both purposive and random sampling methods were carried out in four zones of Northwest Ethiopia to describe the village-based poultry production systems and constraints in order to design future improvement and conservation strategies. The result of this study showed that the majority of the respondents were female (74.16 %). This indicated that most of the time the women, whether in male-headed or female-headed households are responsible for chicken rearing, while the men are responsible for crop cultivation and other off-farm activities. About 99% of the respondents gave supplementary feeds to their chickens. Night shelter was provided by almost all farmers in a part of the kitchen (1.36 %) or in the main house (39.07 %), in handwoven baskets (7.29 %), in bamboo cages (1.51 %) or in a separate shed purpose-made for chickens (50.77 %). The major causes of death of chickens during the study were seasonal outbreaks of Newcastle disease (locally known as 'fengele) and predation. It is important to collect and conserve local poultry breeds before they are fully replaced by the so-called improved exotic chicken breeds. As most of the poultry production is managed by women, focusing on training and education of women will aid not only the improvement of poultry production but also family management, family planning and the overall living standards of the family and the community. In the phenotypic characterization, a total of three hundred chickens were characterized under field conditions for qualitative and quantitative traits following standard chicken descriptors. Seven distinct indigenous chicken populations from four administrative zones were identified. Large phenotypic variability among chicken populations was observed for plumage colour. About 25.49 %, 22.30 %, and 16.40 % of the chickens have white, grayish and red plumage colours, respectively. The rest showed a considerable heterogeneity regarding plumage colours, like black, multicoloured, black with white tips, reddish brown and white with red stripes. The following characteristics were also displayed: plain heads (51.18 %), yellow shanks (64.42 %), and pea comb (50.72 %). About 97.52 % of the chickens did not have feathers on their legs. Variations were also observed in quantitative characteristics such as shank length, egg size and body weight and other reproductive traits exhibited in an intensive management system. In the genetic analysis, indigenous chicken populations representing seven different areas of Northwest Ethiopia were studied using microsatellite markers to determine genetic diversity and relatedness. Three South African chicken lines and two commercial chicken (RIR and WLH) breeds were included for control. A high genetic diversity was observed overall loci and populations with a heterozygosity value of 0.76. The largest heterozygosity (0.93) across all markers was observed in the Mecha chicken population, while the smallest heterozygosity across all loci (0.66) was observed in the White Leghorn breed. A higher genetic distance (lower genetic similarity) between the RIR commercial chicken breed and the Ethiopian indigenous chicken populations were observed compared to RIR and South African fowls. This indicates that the Ethiopian indigenous chicken populations have still not been highly diluted by the RIR commercial chicken breed either through the extension program or through the regional poultry breeding and multiplication institutes. The present result indicated that the clustering of the chicken populations is in accordance with their geographical origin and market places. Microsatellite markers used in this study were found suitable for the measurement of the genetic variation in Ethiopian chicken populations. These results can therefore serve as an initial step to plan the characterization and conservation of indigenous chickens in the Amhara region, Ethiopia. A study on the performance of indigenous chicken populations in terms of growth, carcass yield, egg production and egg quality was evaluated under intensive management conditions compared with the RIR commercial breed. Significant differences were observed among the indigenous chicken genotypes of Northwest Ethiopia for body weight, feed intake, FCR, mortality percentage at different phases of growth, indicating the phenotypic variations of the different chicken ecotypes. The Mecha chickens had the highest growth rate, followed by Guangua and Melo- Hamusit chickens, indicating that these lines are good for meat production. Analysis of carcass characteristics has shown that most of the male and female finisher grower chickens have a higher dressing percentage than the commercial RIR chicken breed managed under intensive management. Furthermore, data on age at point of lay (days) indicated that indigenous chickens reached the first egg production stage from 144 to 168 days, while the RIR breed started producing eggs at 150 days. In general, the current result indicates that the performance of the indigenous chickens is comparable with the RIR breed under intensive management systems. This indicates that there is a chance for better performance if proper selection and breeding plan are designed for indigenous chickens.

[发布机构] University of the Free State