Study on the estimation of genetic parameters and selection efficiency on early part-record for improving egg production in layer
1988
Lee, D.H. | Ohh, B.K. (Seoul National Univ., Suwon (Korea R.). Coll. of Agriculture)
Data on egg number from time of first lay to 71 weeks of age were obtained from samples of single comb white leghorn breeder and brown layer breeder populations which were raised at Manni Breeding Co. These data were used to estimate the heritabilities of age at sexual maturity, early egg number, residual egg number and annual egg number. Also, the genetic correlation coefficients between these traits were estimated and selection efficiencies of each segment in early part record were estimated by use of the heritabilities and genetic correlations. The estimated heritabilities and standard errors in two lines (W and B) were 0.30 +- 0.07 and 0.33 +- 0.08 at early records, 0.19 +- 0.06 and 0.18 +- 0.05 at residual records and 0.37 +- 0.09 and 0.49 +- 0.10 at time of first lay. Those at annual records were 0.24 +- 0.06 equally. The estimated correlation coefficients and standard errors between early record and annual record were 0.76 +- 0.08 and 0.77 +- 0.07. Those between early record and residual record were 0.46 +- 0.15 and 0.39 +- 0.16 respectively. At improving annual egg production per year, selection based on early part record (SM to 40 weeks of age) would be 69 % more efficient than on annual record in line W and 80 % more efficient than on annual record in line B. But, if it were considered that egg weight decreased due to sexual maturity and cost for data collection, use of selected segment from 35-40 weeks of age in line W and from 31-40 weeks of age in line B would be desired in spite of a small loss in relative selection efficiency. The generation interval would not be shortened
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