SELECTION FOR EGG PRODUCTION IN NATIVE CHICKEN AND PERFORMANCE OF ITS CROSSBREDS WITH WHITE LEGHORN
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Date
2019-12-30
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR
Abstract
A study was conducted at All India Co-ordinated Research Project (AICRP)
on Poultry for Eggs, Mannuthy centre, to evaluate the phenotypic and production
characteristics of native chicken of Kerala and to improve its egg production through
selection. From the base generation (G0) of native chicken, 775 female and 200 male
native chicken (G1) were produced through a pedigreed hatch and the pullets were
evaluated till 40 weeks of age for their production performance. Based on egg
number 40, selection was carried out in the population using Osborne’s index and
300 dams and 50 sires were selected for producing G2 generation through a
pedigreed hatch. The pullets were evaluated for their production performance till 40
weeks of age. Heritability and correlation estimates were also worked out for egg
production and various correlated traits of native chicken in both G1 and G2
generations.
The native chicken of Kerala had a hen housed production of 69.83 eggs, hen
day egg production of 70.72 and survivor’s egg production of 70.97. Based on the
selection for egg number 40 in G1 generation of native chicken, the hen day egg
production (4.56 eggs) and survivor’s egg production (5.90 eggs) was significantly
(p<0.05) improved but the improvement in hen housed egg production was not
evident due to higher mortality occurred in G2 generation as a result of incidence of
neoplastic disease of infectious origin in the flock. However, a positive phenotypic
response of 2.26 eggs was obtained on hen housed basis as a result of selection for
egg number 40 in G1 generation. The age at sexual maturity of native chicken was
significantly (p<0.05) improved in G2 generation. Improvement was noticed in the
clutch size of the birds in G2 generation while per cent broodiness was reduced as a
result of selection for egg number 40. The majority of egg shell colour noticed in
native chicken of Kerala was tinted followed by medium brown, white and light
brown. The performance of egg quality, fertility and hatchability percentage were
comparable in both generations.
The sire+dam component of heritability (h²s+d ) for ASM was 0.464 in G1
generation and 0.238 in G2 generation. For the trait egg number at 40 weeks of age,
the values observed were 0.364 and 0.218 in G1 and G2 generation, respectively. The
realised heritability worked out was 0.19. The h²s+d estimates for egg weight in G1
and G2 generation had no much variation among generation, consequent to selection.
The phenotypic correlation (rp) between body weight 16 and egg number 40 was of
low magnitude while egg number and egg weights were nearing zero. The rp between
ASM and egg number was negative. Genetic correlation (rg) between body weight 16
and egg number, between egg weight 28 and egg weight 40 were positive with high
magnitude while ASM with egg number was strong negative. The rg between egg
number and egg weights was not significant. Upon estimating genetic correlation, it
was evident that correlation between most of the traits was higher in G1.The average
effective selection differential for egg number 40 in the generation was 12.03 and the
selection intensity was 0.45. The genetic parameters and phenotypic response for egg
production and various correlated traits revealed that there is further scope for
selection in native chicken of Kerala to improve its egg production.
The study was also aimed at evaluating the production performances of the
selected native chicken in G1 and G2 generation with improved ‘N’ strain of White
Leghorn (IWN). Based on the results of crossbreds (Native x IWN), significantly
(p<0.05) higher number of eggs with early sexual maturity in birds was observed for
the progeny of the birds with IWN as sire and native chicken as dam (ND) than its
reciprocal cross (DN). The performance of the crossbreds with respect to egg weight
and egg quality traits was comparable. The feed intake was higher for ND birds
compared to DN, while livability, broodiness and presence of fawn colour plumage
was higher for DN birds compared to ND. Based on the study of the crossbreds, it
could be observed that ND birds were better in egg production while DN birds were
better in terms of livability, broodiness and plumage. However, field trials have to be
conducted to confirm the present results under backyard conditions.
Description
Thesis Submitted in partial fulfillment of requirement for the degree of Doctor of philosophy in Poultry Science.