Diversity of genetic types of local chickens and introgression with commercial exotic strains in Cameroon

Abstract

Local chicken in Cameroon has a great diversity that is not yet fully explored. The objective of this study was to evaluate the diversity in genetic types of local chickens in Cameroon and level of introgression with exotic strains on the basis of 25 microsatellite markers. The number of alleles per locus varied from 2 (MCW0103) to 22 (LEI0192), with an average of 9.04. The average Ne was 3.78, while the heterozygosity between loci ranged from 0.31 to 0.75 (Ho), 0.33 to 0.86 (He), 0.40 to 0.81 (UHe) and 0.37 to 0.77 (Ht) with means of 0.60; 0.69; 0.65 and 0.63 respectively for the observed, expected, unbiased and total heterozygosity. The inbreeding coefficients FIS, FIT and FST were 0.03, 0.12 and 0.09 respectively. Only an average 4/25 loci significantly deviates from the Hardy-Weinberg equilibrium. Among the local chicken types, the highest Ho was that of naked necks (0.66 ± 0.17). Feathered tarsus and naked necks have the highest diversity across loci (0.67 ± 0.33 and 0.67 ± 0.34). The commercial strains Hybro and Lohman Brown showed excessive inbreeding. Only 4% of the total molecular variance is attributable to phenotypic differences. The number of migrants was high (6.302) showing admixture among populations. The maximum Nei genetic distances are found between exotic broilers and layers strains. Genetic distances between commercial broilers strains and feathered tarsus and with the normal feathered chicken are moderately high but comparable. Genetic distances among types of local chicken are very low, and the genetic identities very high. The dendrograms reveals that genetic types of local chicken are at intermediate position between commercial broilers and layers. Within the cluster of Cameroon local chickens, it is noticed that the Frizzle local chicken is a much more distant sub-group from other four genetic types, while the feathered tarsus and normal feathered chicken are closer. Broilers and layers chicken are clearly divergent, unlike the genetic types of local chickens. Local chicken types have variable levels of introgression with the various exotic broilers and layers strains. The local normal feathered chicken, although differing from exotic strains presents various introgression levels ranging from low (Lohman Brown) to medium (Arbor Acres and Hybro) and high (Rhode Island Red). In general only 35% of the chicken genomes found in Cameroon could be considered as pure or fully belonging to their respective strains.

Key words: chicken, diversity, genetic types, introgression