Diversity among local chicken ecotypes in Tanzania.
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Date
2003
Authors
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Publisher
Sokoine University of Agriculture.
Abstract
This study was conducted in order to establish the genetic and phenotypic diversity among nine local chicken ecotypes of Tanzania namely Ching’wekwe, Kuchi, Mbeya, Morogoro-medium, N’zenzegere, Pemba, Singamagazi, Tanga and Unguja in a series of five experiments. The first experiment determined the genetic diversity among the ecotypes using manual microsatellites typing. Allele numbers, genetic distancing, differentiation (Gst), and individual associations were established between the nine local detected across all loci ranging between 4 and 15 per loci. Up to 100% (n = 13) of individuals in some ecotypes clustered together. The phylogenetic trees grouped the productivity and reproductive performance of the ecotypes. Weekly weight measurements and growth rates were evaluated for each ecotype and sex of the birds as between ecotypes in the parameters studied. Ching'wekwe showed consistently low productivity contrary to Morogoro-medium and Tanga ecotypes often showing higher values. The third experiement assessed the disease resistance potential by challenging one-week old chicks with 2.54 x 10'8 CFU of virulent S. gallinarum strain. For 14 days, clinical signs, necropsy findings, antibody titres, haematocrit, leukogram, growth rate differences in the leukogram; viable bacterial cell counts as well as the effect on growth chicken ecotypes and phylogenetic trees were constructed. In total, 152 alleles were and viable bacterial cell counts in the liver and spleen were recorded. There were was egg weight, fertility and hatchability. Significant differences (P<0.05) existed chickens by geographical and historical origin. The second experiment was on rate between the different ecotypes. Based on clinical signs and mortality, N’zenzegere and Mbeyci ecotypes as well as the commercial layer strain appeared to be the most severely affected. The fourth experiment studied the responses of ecotypes to Newcastle disease vaccine. Parents (hens) were vaccinated and HI titres measured after two weeks on hens, eggs and chicks hatching from the eggs. Some chicks were monitored until their HI litres were zero and then were vaccinated against Newcastle disease. HI titres
titres were observed for a further 28 days. The HI titres in chicks were higher than those
of hens and eggs. Tanga ecotype showed early protective immunity while Morogoromediuni and Mbeya ecotypes showed persistently higher responses. The fifth experiment assessed the productivity and reproductive performance of the local chickens under freerange system. Wide ranges were detected in the parameters investigated and there were significant differences in productivity between the different farmers. The overall hatchability was 80% with ranges between 33 and 100%. It was concluded that genetic and phenotypic diversity exists in the local chicken ecotypes of Tanzania. The diversity constitutes a valuable resource for use in breeding programmes for improvement of the health and productivity of the local chickens and in designing proper conservation strategies. Further studies are required to identify genetic markers associated with the performance of the Tanzanian medium ecotype (Morogoro-mediuni and Tanga) is required to ascertain their suitability for promotion throughout the country. productivity and disease resistance within the local chicken ecotypes. In depth studies on
were monitored weekly for 28 days; 70 days later, the chicks were re-vaccinated and titres were observed for a further 28 days. The HI titres in chicks were higher than those
of hens and eggs. Tanga ecotype showed early protective immunity while Morogoromediuni
and Mbeya ecotypes showed persistently higher responses. The fifth experiment
assessed the productivity and reproductive performance of the local chickens under freerange
system. Wide ranges were detected in the parameters investigated and there were
significant differences in productivity between the different farmers. The overall
hatchability was 80% with ranges between 33 and 100%. It was concluded that genetic
and phenotypic diversity exists in the local chicken ecotypes of Tanzania. The diversity
constitutes a valuable resource for use in breeding programmes for improvement of the
health and productivity of the local chickens and in designing proper conservation
strategies. Further studies are required to identify genetic markers associated with
the performance of the Tanzanian medium ecotype (Morogoro-mediuni and Tanga) is
required to ascertain their suitability for promotion throughout the country.
Description
Keywords
Phenotypic diversity, Local chicken ecotypes, Genetic, Ching’wekwe, Kuchi, Morogoro, Tanga, Mbeya, Newcastle disease