Towards Conservation of Omani Local Chicken: Management, Performance and Genetic Diversity
von Badar Al-Qamashoui
Datum der mündl. Prüfung:2014-02-10
Betreuer:Prof. Dr. Eva Schlecht
Gutachter:Prof. Dr. Henner Simianer
Gutachter:Dr. Steffen Weigend
EnglischMany rural families in Oman are engaged in agricultural and animal husbandry activities with a majority still depending on farming as a main source of income. Local chicken farming in Oman represents one of the main agricultural activities that provide opportunities for food security and income for many rural families. Despite its importance, there is no detailed study for evaluating the production system, production performance and genetic potential of local poultry in Oman. The present thesis aimed at: 1. Characterizing the local chicken management, production and marketing strategies of small scale farming; 2. Assessing the production traits and phenotypic features of Omani local chickens; 3. Evaluating the genetic makeup and diversity, and assess the conservation possibilities for traditional chicken types in Oman; 4. Contributing to tracing the maternal origins of chicken populations in Oman as well as in the Arabian Peninsula. The present thesis consists of three studies. In the first study, a structured questionnaire was used to collect data from 163 households distributed across 18 villages in Oman’s six major agroecological zones. These were: Batinah (BT), Dhofar (DF), North Hajar (NH), East Hajar (EH), Musandam (MU), and East Coast (EC). Free-range scavenging was the dominant production system, but 58.5% of the respondents offered commercial feed supplements to their chicken. The purposes of chicken keeping were: egg production for domestic use (69%) and income generation (31%). Omani local chickens widely vary in plumage color patterns, comb types, shank colors and other phenotypic characteristics. Male and female body weight also varied, being 1.34 ±0.65 kg and 1.14 ±0.86 kg (P<0.05), respectively. Flock size averaged 22 ±7.7 chickens per household with 4.8 hens per one cock. Clutch size was 12.3 ±2.85 eggs and annual egg production averaged 64.5 ±2.85 eggs per hen. Egg hatchability was 88% ±6.0, and annual chicken mortality across all age and sex categories was 16% ±1.4. Predators were the major production constraint (26.5%), followed by high feed prices, low egg production and low chicken body growth. Logistic and multiple regression analysis showed that several socioeconomic factors of chicken owners influenced feeding, housing, and health care of the chicken (P<0.05). The strong involvement of women makes them key stakeholders in future development and conservation programs of local chicken. In the second study, twenty-nine microsatellite markers were used on 158 birds from the above six agro-ecological zones. Across loci and populations, a total of 217 alleles were observed. Across populations, the average number of alleles per locus was 7.48 and ranged from 2 (MCW98 and MCW103) to 20 (LEI094). Across populations, the mean expected heterozygosity (HE) was 0.62. The mean global deficit of heterozygotes across populations (FIT) was 0.159 while average fixation index (FST) between populations was 0.034, indicating a low population differentiation. Based on Nei’s genetic distance a neighbor-joining tree was constructed for the populations, which clearly identified the Dhofar population as the most distant one of the Omani chicken populations. The analysis of conservation priorities identified DF and MU populations as the ones that largely contribute to the maximal genetic diversity of the Omani chicken gene pool. In the third study, sequencing data from a fragment of the control region of mitochondrial genome (mtDNA) from 175 individuals and 32 published sequences was used to assess genetic diversity and inference on the maternal origins of local chickens from the Arabian Peninsula (Oman, Saudi Arabia, Yemen, Isle of Socotra) and the Horn of Africa. Because of its role in the human movements between Asia and Africa and to investigate the dispersal of chicken around the Indian Ocean Rim, sequences from Africa and India were also included in this study. We found a total of 27 haplotypes with an average haplotype diversity of 0.7588 ±0.0300, clustering into three of the previously identified phylogenetic clades. The most frequent observed haplotypes from the Arabian Peninsula (and Socotra) clustered in clade E, which is supposed to have originated on the Indian subcontinent. While samples from Somalia belong mostly to clade C, which supposedly has its roots in Southeast Asia, a few individuals, mostly from North Oman, clustered in clade A, originating from Southeast and/or East Asia. The wide presence of clade E on the Arabian Peninsula points towards a major influence of the Indus Valley as center of origin in the genesis of Arabian local chicken. Isolation by distance tests showed that chicken diffusion across the Indian Ocean is correlated with the proximity to the main centers of chicken domestication. The high frequency of haplotypes originating from the Indian Subcontinent domestication event, on the Arabian Peninsula, provides interesting insight into the role of the Peninsula in the diffusion of livestock around the Indian rim.
Keywords: Animal genetic resources; egg production; rural smallholders; scavenging system; task division; Genetic diversity; conservation; microsatellites; Omani chicken; Arabian Peninsula; dispersal routes; Indian Ocean; mtDNA; Animal genetic resources; egg production; rural smallholders; scavenging system; task division; Genetic diversity; conservation; microsatellites; Omani chicken; Arabian Peninsula; dispersal routes; Indian Ocean; mtDNA