|
|
| |
| Articles
by
F.O. Abeke |
Total Records (
2 ) for
F.O. Abeke |
|
 |
| |
|
| |
B.I. Nwagu
,
S.A.S. Olorunju
,
O.O. Oni
,
L.O. Eduvie
,
I.A. Adeyinka
,
A.A. Sekoni
and
F.O. Abeke
|
| |
Data from 4336 pullets progeny
of 144 sires and 779 dams for strain A and 4843 pullets, progeny of
158 sires and 1108 dams for strain B belonging to 5 generations under
selection for part-period egg production to 280 days of age were used
for this study. The number of pullets housed at about 18weeks per population
ranged from 326 and 1000 per generation for each of the population.
The effective number of parents in each generation averaged 174 and
187 for male and female populations, respectively. The traits measured
were egg number to 280 days (EGG280 D), age at sexual maturity (ASM),
egg weight average (EWTAV) and body weight at 40 weeks of age (BWT40).
The co-efficient of inbreeding per generation due to finite population
size was 0.005 for both the male and the female lines respectively.
For the control population the values obtained were 0.008 vs 0.007 for
both the male and female lines respectively. The average performance
of the birds over the study period for the male and female lines respectively
ranged from 38.38 vs 50.94 and 37.03 vs 51.25 for EGG280 D, 194 vs 212
and 197 vs 214 for ASM, 48.29 vs 55.93 and 48.29 vs 55.11 for EWTAV,
1600 vs 1754 and 1440 vs 1908 for BWT40.The effective number of parent
in each generation averaging about 175 probably caused an average inbreeding
of about 0.5% per generation. Although the level of inbreeding in this
population is not critical there is evidence of an increasing trend,
which could lead to homozygosity in the flock. There is need to widen
the genetic base to prevent selection depression too early in the flock. |
|
| |
|
| |
B.I. Nwagu
,
S.A.S. Olorunju
,
O.O. Oni
,
L.O. Eduvie
,
I.A. Adeyinka
,
A.A. Sekoni
and
F.O. Abeke
|
| |
Records obtained from 4336
pullets progeny for strain A and 4843 pullets, progeny for strain B
under selection for part-period egg production to 280 days of age were
used for this study. The response variables measured were Age at sexual
maturity (ASM), Egg number to 280 days (EGG280 D), Egg weight average
(EWTAV) and Body weight at 40 weeks of age (BWT40). The genotypic response
was only 0.42 eggs per generation in the male line. The female line
population showed a much higher positive response to selection, the
phenotypic value being 1.67 eggs per generation while the genotypic
response was 3.1 eggs per generation. The genetic correlation estimates
between the different economic traits ranged from -0.70± 0.38 to 0.82
± 0.42 vs -0.71 ± 0.47 to 0.76 ± 0.29 for the male and female lines
respectively. The correlation between egg number and egg weight was
small non significant. ASM was highly and negatively correlated with
egg production to 280 days in both lines being higher than- 0.60 in
most cases. The genetic correlation between egg number and BWT40 showed
no definite trend. In the female line, correlated response in age ASM
and BWT40 had negative values. In the male line however except for BWT40
which showed a positive correlated response of 3.4g/year, all other
traits showed negative correlated responses. Generally it was evident
that selection was more effective in improving the egg number in the
female line than in the male line showing an increase of 1.67 vs 0.19
eggs per year in the female and male lines, respectively. The low egg
number reported was as a result of the delay in sexual maturity especially
during the later years of the selection experiment. Another factor that
may have contributed to the variable response achieved from generation
to generation may also be due to varying season of hatching across generation.
However the positive response in the female line population may be attributed to reduced age at sexual maturity. |
|
|
|
|
| |
|
