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젖소 유전능력평가에서 Contemporary Group 의 최적 , 최소 크기에 관한 연구
도창희 한국동물자원과학회 2000 한국축산학회지 Vol.42 No.2
Three, 6 and 9 of contemporary group sizes by five types including conventional genetic evaluation were examined with simulated data to study accuracy of estimation. Four alternatives were suggested. Method l and 2 assumed that genetic values of cows missing sire identity were population and contemporary group average. Method 3 and 4 accounted for genetic values through producing abilities estimated as random and fixed effects, respectively. Contemporary group effects were estimated more accurately as contemporary group size increased(3, 6 and 9), but breeding values were less increased in accuracy. Accuracies of alternative methods slightly exceeded those of conventional method for all estimated effects and all minimum group sizes. Method 3 had high increases in accuracy compared with the other alternatives. In the estimation of contemporary group effects, there were significant differences of increases in accuracy among the group sizes 3, 6 and 9. No significant differences in increases of accuracy in the estimation of cow and sire breeding values were shown among the group sizes.
국내 홀스타인종 유우의 부분산유기록을 확장하기 위한 비율계수 추정에 관한 연구
도창희,오봉국,이정구,이문연 ( C . H . Do,B . K . Ohh,J . K . Lee,M . Y . Lee ) 한국축산학회 1986 한국축산학회지 Vol.28 No.3
Ratio factors for extending partial records to 305day were estimated on 3,740 complete lactation rewrds collected from 6 Holstein herds from 1969 through 1984. The results obtained are as follows: 1. The single monthly ratio factors were higher in the late stage than in the early stage, and higher for the 1st parity than the 2nd, 3rd and later partities. The value of R² of the factors was relatively high in the middle stage (4th-7th month). 2. The cumulative monthly ratio factors were also higher for the 1st parity than the other parities, and lower in July through October than in the other months. The value of R2 of the factors increased as monthly tests continued; and over 0.80 if the number of monthly test record included more than 5. 3. The ratio factors for the period of unknown part on the last monthly yield decreased while the value of R² of the factors increased as the period of unknown part became short.
도창희,오봉국 ( C . H . Do,B . K . Ohh ) 한국축산학회 1985 한국축산학회지 Vol.27 No.12
The data consisted of 3,740 Holstein lactations at six dairy farms from 1969 to 1984 in Korea. In order to estimate the extension factor the S78 incomplete records were deleted and 3,162 records were only used. The generalized least squares analysis for milk yield used a model including mean, herd, year, season and parity as fixed effects. In order to investigate accuracy for each extension factors, variance of difference. between actual and estimated yield were estimated. The effects of herd, calving year, calving month and parity for milk yield were highly significant (P$lt;0.01), and were mostly influenced at 8-10th, 2-4th and 1-3rd lactation stage respectively. In order of size of variance of difference between actual and estimated yield, method P showed the smallest variance, followed by the methods of multiple regression factor, ratio factor (estimated the remaining part of the lactation from the yield on the last test day), cumulative regression factor and cumulative ratio factor. When environmental effects such as herd, calving year, calving month or parity were not eliminated, variance generally became larger. The extension factor using ratio increased the variance of difference by about 2S% and that using regression increased the variance of difference from 38.61 to 48.0%.