Abstract
The study was conducted to investigate the performances of BLRI improved three indigenous chicken varieties e.g. Non-descript (ND), Hilly (HI) and Naked Neck (NN) under farmer's condition and to estimate genetic diversity, population structure, genetic distance and/ or relationship among the experimental chicken varieties using microsatellite markers. Initially, growth performances up to 8th week of age under intensive condition were investigated for both the BLRI improved varieties and locally available Non-descript (LND) chicken. After that the productive and reproductive performances of the birds were investigated up to 72 weeks of age under semi-scavenging system of rearing at farmer's premises. The experiment was replicated in 3 different Upazila's of Bangladesh (Nakla, Sherpur; Dinajpur Sadar and Dumuria, Khulna). A total of 20 farmers were selected from each Upazila having 4 different groups for rearing 4 genotypes (ND, HI, NN and LND) and each genotype replicated 5 times considering LND group as control. The live weight, egg production, egg weight, clutch size, and mortality were recorded. Creep feeding (CF) trial was conducted to observe the effect of CF on the performance of indigenous hens (ND) and their chicks up to 8th week of age in 3 locations dividing the farmers into 2 groups (creep feeder versus no creep feeder). Feed intake up to 8th week of age was influenced by location (p<0.001); while it was found non-significant for genotypes except at 8th week of age (p<0.05). The average live weight of BLRI improved (ND, HI and NN) and LND were influenced by genotype and location (p<0.001) up to 8th week of age. The average live weight of BLRI improved varieties at 8th week of age attained 560g which is about 100g more than that of LND. Feed conversion efficiency of BLRI improved varieties were found better than the LND at all ages. The feed efficiency of ND, HI, NN and LND at 4th and 8th week of age was 3.4, 2.6, 3.5 and 3.9; and 3.6, 2.9, 3.5 and 5.9, respectively. Live weight of 4 genotypes of chicken at 10-18th week of age varied (p<0.001) for genotype, location and their interactions. Live weight at 18th week of age for the HI, ND, NN and LND was 1550, 1350, 1300 and 1128g/bird, respectively. Among the 4 varieties HI weighed always more than the other varieties and the LND found the lowest rank up to 72 week of age in all 3 locations. Age and live weight at sexual maturity recorded for ND, HI, NN and LND were 150, 144, 139 and 145 days and 1440, 1646, 1373 and 1203g/bird, respectively. The annual egg production, first egg weight, clutch length and egg per clutch were highly influenced (p>0.001) by genotype and location. The highest number of annual egg recorded from NN followed by HI, ND and the lowest for LND that were 155, 154, 150 and 105 numbers of eggs per bird, respectively. The average highest clutch was recorded for NN (6) followed by LND (5.62), ND (5.47) and HI (5.34). Number of eggs per clutch was recorded for HI (27.68), NN (27.42), ND (26.30) and LND (20.77). The egg weight at 30, 40, 50 and 60 week of age were highly influenced (p<0.001) by genotype, location and their interactions. The hatchability was influenced by location and the fertility and hatchability ranged between 86 to 90 and 70 to 72%, respectively irrespective of genotypes and locations. The mortality of 4 genotypes of chicken at different ages were not influenced (p>0.05) by genotype, but was influenced (p<0.001) by location. The external egg quality attributes like shape index, breaking strength and shell thickness were influenced (p<0.001) by genotype and location. The internal egg quality traits e.g. albumen length, HU and yolk color score influenced (p<0.001) by genotype and location while yolk width and yolk weight varied significantly (p<0.05) for genotype. In CF trial hen weight loss, resume laying, clutch size and clutch length were highly influenced (p<0.001) by the two rearing systems. The hens of CF group resume laying about 2 weeks (13 days) earlier than the NCF group. Subsequently, the hens of CF group laid 29 eggs by 33 days and NCF hens produce 23 eggs by 38 days. The fertility and hatchability were higher in CF group than the NCF group as 82 and 76%, and 76 and 70%, respectively. The 8th week chick weight was 200 g more in CF group than NCF group and the mortality was significantly (p<0.01) higher in NCF group (19%) than CF group (11%). The findings of the current study revealed that the BLRI improved varieties (ND, NN and HI) performed better than the LND chicken in terms of all productive and reproductive performances under semi-scavenging rearing system. The molecular study was included BLRI improved 3 varieties (ND, NN and HI) and, red Jungle fowl (JF) and Aseel (AS). A total of 161 DNA samples comprising 5 chicken populations were discriminated using 16 highly polymorphic microsatellite markers. The result showed that the mean number of alleles ranged between 5.81 (in JF) and 7.13 (in ND). The average observed and expected heterozygosity in the studied populations was 0.67 ± 0.01 and 0.70 ± 0.01, respectively. AMOVA analysis revealed 88.07 % of the total genetic diversity was accounted for within population variation and the rest 11.93 % was incurred with population differentiation (FST). The result indicates lower genetic differentiation among the studied populations. Structure analysis depicted that the studied samples can be categorized into 4 distinct types (AK=3.74) or varieties (ND, NN, HI, AS/JF) where AS and JF grouped together. The phylogenetic analysis showed two separate clusters among the 5 chicken populations of Bangladesh while HI positioned at the separate group. These results provided important insight in relation to genetic diversity and population structure aspects which could be utilized for Bangladeshi chicken genetic resource conservation as well as future breeding strategy development. Considering both the field trial and molecular results further research and breeding should be conducted to sustain the continued improvement.