Studies on the prospects of improving the performance of the local chicken population in Tanzania by crossbreeding
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Date
1990
Authors
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Journal ISSN
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Publisher
Sokoine University of Agriculture
Abstract
The present study was initiated to explore the possibilities
for developing high performing dual purpose strains of chickens
adapted to low input production conditions in Tanzania.
Exotic meat type, egg type and local chickens were compared for
performance along with the crosses between these breeds in one year.
In the following year the comparison involved the three basic
breeds, the second generation crosses (F ), backcrosses, and three
breed crosses of these breeds.
Additional data were acquired from
a crossbreeding experiment in Egypt, in which two Egyptian breeds,
two White Leghorn lines from Norway, and crosses between Egyptian
and Norwegian stocks were involved.
Constant estimates of various genetic components
(additive
genetic, heterosis and reciprocal ) were obtained as coefficients
of a multiple regression equation, in which the observation on each
individual for a given trait was the dependent variable.
The
independent variables consisted of coded values ranging from 0
to 1.
The general superiority of the germplasm from exotic breeds
to that of indigenous breeds was demonstrated for nearly all traits
considered.
However, there was an indication for this superiority
to decline as environmental conditions deteriorated.•Important heterosis effects were
revealed-, mainly for juvenile
body weights and egg production traits, including the age of
sexual maturity.
Evidence was revealed to suggest the existence
of negative heterosis for body weights and egg
size in some
crosses.
Reciprocal effects were found to be important in crosses
involving heavy breeds and light breeds, as well as in crosses
involving crossbred parents.
It is concluded from these results that the high potential
inherent in exotic breeds for productive traits would not be
fully realized under environments pertinent with low input
production systems.
Some adjustment in the genetic content of the
stocks would be necessary in order to make them adaptable to
less optimum conditions.
One of the most prospective approaches is
to make some kind of crosses between exotic and indigenous
chickens, followed by selection for high productivity under the
sub-optimum conditions.
Selection for specific adaptive qualities would be carried out if such qualities were detected.
Description
Thesis
Keywords
Local chicken, Tanzania, Crossbreeding