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Desired-gain
selection indices for improving performance of two Tanzania
local chicken ecotypes under intensive management
J. Lwelamira1*
and G. C. Kifaro2
*Corresponding author. E-mail:
jlwelamira@yahoo.com.
1Institute
of Rural Development Planning, P. O. Box 138, Dodoma,
Tanzania.
2Department
of Animal Science and Production, Sokoine University of
Agriculture, P.O. Box 3004, Morogoro, Tanzania.
Accepted 5 January, 2010 |
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A study was carried out to evaluate various desired-gain
selection indices (Yamada index) in improving performance of
two chicken ecotypes of Tanzania viz. Kuchi and Tanzania
Medium (Medium). The indices for Kuchi ecotype were geared
at improving body weight at 16 (Bwt16) weeks of age while
those for Medium ecotype were geared at improving egg
production and related traits. These traits included age at
first egg (AFE), egg production in the first 90 days after
sexual maturity (EN-90) and egg weight (EW). Apart from
production traits, antibody responses (Ab) against Newcastle
disease virus vaccine was also included in some selection
indices in both ecotypes. Furthermore, correlated responses
to some egg quality traits namely egg shape index (ESI) and
eggshell thickness (STH) were also studied. Results
indicated that it would take between 5 to 6 generations of
selection in Kuchi to improve Bwt16 either singly or
together with Ab from their current levels of 1394 g and 5
(HIlog2) to the desired averages of 1800 g and 6
(HIlog2), respectively. On the other hand results
indicated that it would take between 8 to 11 generations of
selection in Medium ecotype to improve either AFE and EN-90
or together with EW or Ab or both of them from their current
averages of 168 days, 49 eggs, 42 g and 5 (HIlog2)
to the desired averages of 154 days, 68 eggs, 50 g, and 6
(HIlog2), respectively. Based on the number of
generations required to achieve desired gains and correlated
responses, some selection indices were recommended.
Key words:
Breeding, desired gain, local chicken, selection indices. |
