Response to selection and genetic parameters of body and carcass weights in Japanese quail selected for 4-week body weight.
The current study was conducted to investigate the effect of short-term selection in Japanese quail for 4-wk BW and estimate genetic parameters of BW, carcass traits, and egg weight. A selected line and control line were randomly selected from a base population. In each generation, 39 sires and 78 dams were used as parents for the next generation. Data were collected over 2 consecutive hatches for 4 generations, and 1,554 records from 151 sires and 285 dams were used to estimate the genetic parameters. The genetic improvement of 4-wk BW was 9.6, 8.8, and 8.2 g in generations 2, 3, and 4, respectively. There was a significant effect of sex, generation, and line (P < 0.001). There was a significant difference for BW and carcass weights but not for carcass percentage components between sexes (P < 0.01). Females showed higher figures than males. The realized heritability for 4-wk BW was 0.55, reflecting the accuracy of selection. However the estimated heritability by using pedigree information was 0.26 +/- 0.05. The genetic correlation among BW and carcass traits was relatively high (ranging from 0.85 to 0.91). Inbreeding caused a decline in the mean for all of the traits, but its effect was only significant for 4-wk BW and carcass weight (P < 0.05). Selection for 4-wk BW improved feed conversion ratio 0.16 units over the selection period. Results showed there was a strong genetic correlation between 4-wk BW and carcass traits that suggests that early 4-wk BW can be used as a selection criterion to improve carcass traits. Also, intense selection resulting in high rates of inbreeding might result in decreased response to selection due to inbreeding depression.
Khaldari
M
M
Department of Animal Science, Faculty of Agriculture, University of Tehran, PO Box 4111, 31587-77871 Karaj, Iran.
Pakdel
A
A
Mehrabani Yeganeh
H
H
Mehrabani Yegane
H
H
Nejati Javaremi
A
A
Berg
P
P
D000818:Animals; D001823:Body Composition / Q000235:genetics*; D001835:Body Weight / Q000235:genetics*; D003370:Coturnix / Q000235:genetics* / Q000502:physiology*; D005260:Female; D007178:Inbreeding; D008297:Male; D012641:Selection, Genetic