dc.description.abstract |
For a large number of people living in rural areas, poultry contribute
the major source of livelihood in bridging some socioeconomic gaps
by supplying food and income and hence should be included in rural
development strategies. Such bridging role of poultry is attributed to
its fast generation interval and high reproductive rate, prolific nature,
easy to raise and their output can be generally expanded more rapidly
and easily than that of other livestock.
Ethiopian has 65 million poultry population (FAO, 2000) that
comprise of about 99 % of indigenous chickens (Alamargot, 1987).
Indigenous chickens in Ethiopia are predominantly raised where
traditional family-based free-range scavenging management system
is practiced (Alemu and Tadelle, 1997). Thus, the birds are left to
depend primarily on what nature offers.
Indigenous chickens are constrained by inadequate information at all
stages of research and development. Very limited information is
available from the scattered efforts of research and development
concerning these genetic resources. Thus, what has been studied so
far on these animals is not tangible enough to show the relative
effects of genetic and non-genetic factors on performance of
indigenous chickens (Alemu and Tadelle, 1997). The cause for
inadequate research and development efforts on poultry in Ethiopia
could be associated to the lack of priority in development agenda. As
a result, efforts on these animals have long been interplayed between
“on and off” until poultry research is recognized and established as
one of the national research commodity to date.
Generally, despite the fact that indigenous chickens are huge in
population and occasionally they have been considered to be disease
resistant and adaptive to their environment, their contribution to
human nutrition, gross domestic products, and export earnings are disproportionately low. Such sub-optimal production has been
related to delivery of a low standard of management, health care and
feeding. There is a general tendency that improvement in
management, health care and nutritional status of indigenous
chickens could result in increased output per bird. Thus, there were
attempts to rear indigenous chickens under confined management
with improved management, health care and nutritional status in
various geographical areas of the country (Teketel, 1986; Abebe,
1992; Brannang and Pearson, 1990; Solomon, 2003), but all have
failed due to serious problem of high morbidities and mortalities.
The cause of failure of native chickens to survive under confined
environment as repeatedly proved from high morbidity and mortality
is not adequately addressed yet. Therefore, this study was intended to
describe the etiology for unsuccessful survival of the chickens under
confined management. The study also assessed the prevalence,
clinical and pathological manifestations and extent of mortality,
mean length of survival, mortality pattern, and incidence of mortality
of five chicken ecotypes during the diagnostic phase. The extent and
effectiveness of vaccination in reducing mortality to the natural
challenge of Marek's disease (MD) during intervention phase was
also investigated. |
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