GENETIC STUDIES ON GROWTH, PRODUCTION AND IMMUNOCOMPETENCE OF JAPANESE QUAILS (Coturnix coturnix japonica) UNDER SELECTION
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Date
2009
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
ABSTRACT :
An investigation was made on the Black (3,438) and Brown (3,710) Japanese quails (Coturnix coturnix japonica) under selection in generations 8, 9 and 10 for high 4-week body weight, maintained at the Poultry Experimental Station (PES), Rajendranagar, Hyderabad, to estimate the genetic and phenotypic variation in the growth, production and reproduction performance and to estimate the genetic progress in various economic traits. The immunocompetence levels, genetic parameters and genetic progress in various traits were estimated. Selection indices based on body weights, Age at first egg, Egg production, Egg weight and Egg mass were developed.
The overall least squares means for body weights at day-old to 4 weeks of age were 9.41+0.01, 33.23+0.08, 71.61+0.16, 121.96+0.24 and 173.66+0.07 g respectively. The strains had significant influence on body weights from day-old to 4 and 8 to 20 weeks of age, whereas the influence of generations was significant from day-old to 16 weeks of age. Sex effect was significant on 2, 3 and 4 weeks body weights, while hatch had significant influence from day-old to 20 weeks of age. The body weights of Black strain were superior to Brown from 1 to 20 weeks of age.
The overall least squares mean Age at first egg was 56.26+0.51 days, which was significantly influenced by generation and hatch. Strain and generations influenced the egg production upto 16 and 30 weeks, whereas hatch effect was significant on egg production upto 30 weeks only. The overall least squares means for egg production was 30.85 and 73.02 upto16 and 30 weeks of age, respectively. The Black strain matured earlier and produced more number of eggs than Brown strain. The generation and hatch had significant influence on egg weight. The overall least squares mean egg weight was 14.22 g. The overall least squares means for Average daily gain during 1, 2, 3 and 4 weeks of age and cumulative growth rate from 1 to 4 weeks age were 3.10, 5.47, 7.16, 7.35 and 23.46 g respectively. The Average daily gain of Black Japanese quails was significantly higher than those of Browns at all the ages. The females had significantly higher average daily gains than males. The overall least squares means for feed conversion ratio upto 6 weeks age, feed intake per dozen eggs and kg egg mass upto 7-30 weeks age were 1.70, 2.49, 2.95, 3.52, 4.67, 6.30, 750.93 and 4,070.05 g respectively. The influence of sex was significant on Feed conversion ratio. The overall least squares means for HA titers at 5th and 10th day of post inoculation and Foot pad index were 4.48, 2.00 and 0.16 in Black and 5.44, 2.14 and 0.26 mm in Brown strain respectively. The heritability estimates of body weights varied from low to high, while they were low for age at first egg in Black (0.04 to 0.13) and Brown (0.07 to 0.15). The estimates for egg production upto 30 weeks of age varied 0.02 to 0.08 in Black and from 0.02 to 0.07 in Browns. The heritability of egg weight was found to be low. The heritability estimates for feed conversion ratio were low to medium in Black (0.03 to 0.32) and low to high (0.02 to 0.59) in Browns. The Haemagglutination titer has low to medium (0.18 to 0.35) heritabilities in both the strains, whereas Foot pad index was low heritable (0.02 to 0.04).
Genetic, phenotypic and environmental correlations for body weight at various ages varied from low to high in magnitude. Age at first egg was correlated negatively (-0.11 to -0.16) with egg production and positively with egg weight at genetic level, while the estimates among different ages of egg production were high. The association between egg production and egg weight was negative at genetic and phenotypic level. The genetic correlations among average daily gains were in general positive at all ages. The genetic correlation between body weights and Feed conversion ratio were positive, while the weight gain was phenotypically negatively correlated with feed conversion ratio. The genetic correlations of body weights at early age with Haemagglutination titers and FPI were positive but low. The Foot pad index had positive genetic correlation with Haemagglutination titers in two strains. The genetic progress in body weight at 4-weeks age varied from 6.25 to 6.74 g in Black and from 7.24 to 8.46 g in Brown strains. The linear regression equations were fitted for predicting the Haemagglutination titers and Foot pad index based on the body weights which had lower R2 - values. A total of 112 selection indices were computed based on the body weights at 1, 2, 3 and 4 weeks of age and dams AFE, dams EP16, dams EW16 and dams EM16. At 4-weeks of age of selection the selection indices consisting of BW4, dams EP and dams EM (I52) and BW4, dams AFE and dams EM (I49) in Black strain and those with BW4, dams EP16 and dams EM16 (I52) and BW4, dams AFE, dams EP16 and dams EM16 in Brown strain were found to be ideal ones. These indices are expected to reduce the AFE, increase the EM (which takes care of EP and EW) and keep the body weight either constant, reduce marginally or increase
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