• Asian-Australasian Journal of Animal Sciences
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• 제19권6호
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• pp.769-774
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• 2006

Fractions of herd-year-season, sire by herd interaction, additive genetic and dominance genetic variances were estimated for milk production traits in Holsteins of Japan using Method R. Inbreeding depressions for milk production traits were also estimated. Estimated fractions of herd-year-season variances ranged from 0.056 to 0.074 for yield traits and from 0.033 to 0.035 for content traits. Estimated fractions of additive genetic variances to phenotypic variances (heritabilities across a herd in the narrow sense) were 0.306, 0.287, 0.273, 0.255, 0.723, 0.697 and 0.663 for milk, fat, SNF and protein yields, and fat, SNF and protein contents, respectively. Estimated fractions of dominance genetic variances ranged from 0.019 to 0.022 for yield traits and from 0.014 to 0.018 for content traits. Fractions of variances for sire by herd interaction were estimated to range from 0.020 to 0.025 for yield traits and 0.011 to 0.012 for content traits. Estimates of inbreeding depression for milk, fat, SNF and protein yields were -36.16 kg, -1.42 kg, -3.24 kg and -1.15 kg per 1% inbreeding for milk, fat, SNF and protein yields, respectively. Estimates of depression per 1% inbreeding for content traits were positive at $0.39{\times}10^{-3}%$, $0.31{\times}10^{-3}%$ and $0.82{\times}10^{-3}%$ for fat, SNF and protein contents, respectively.

• 한국잠사곤충학회지
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• 제31권1호
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• pp.20-24
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• 1989

7개 누에 품종으로 이면교잡하여 42개의 조합의 F1, F2세대에 대한 양적형질의 잡종강세와 약세현상을 검정한 결과는 다음과 같다. 잡종강세가 대체로 높은 형질은 견사량이 F1, F2세대의 I·II집단에서 15.57-38.69%, 단견중과 견층중은 F1, F2세대의 I·II집단에서 각각 11.29-21.65%, 7.44-23.73%로 정의 유의인데 반하여 5령경과와 연감율은 F1, F2세대의 I·II집단에서 각각 -0.57--6.62%, -1.74--6.06%의 부로 유의하였다. 단견중, 견층중, 견사장, 견사량 등의 수량적 형질은 F1세대가 F2세대보다 또 교배 I집단이 교배 II집단보다 높은 강세를 보였다. 큰 친에 대한 Heterobeltiosis는 단견중이 F1세대의 I·II집단에서, 견사량이 F1세대의 I집단에서 각각 정으로 유의하였고, 5령경과, 견층비율, 연감율은 F1, F2세대의 I·II집단에서 각각 부로 유의하였다. Inbreeding depression현상은 견층비율과 연감율이 교배 I·II에서 유의하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제15권6호
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• pp.767-771
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• 2002

Breeding efficiencies were compared among three population schemes: a single population, a population with two subpopulations and a population with three sub-populations. A simulation experiment of selection was carried out for 10 generations with 20 replications each by comparing average breeding values and inbreeding coefficients among the three population schemes. Phenotypes of three traits were generated with a model comprising 36 loci, each with additive genetic effects and residuals distributed normally. Among the three population schemes, the single population scheme was definitely superior to the other two with regards to selection response and inbreeding. The multiple sub-population scheme was, however, considered to be an alternative population scheme when the difference in economic weights of the traits was small among the sub-populations, assuming moderate inbreeding depression for traits and crossbreeding. The scheme with two sub-populations had a higher genetic value than that with three subpopulations; however, the genetic values of the schemes were comparable when maternal heterosis was taken into account. The choice of population schemes may depend on the cost-sharing policy between the breeding population and the commercial population rather than just the breeding efficiency.

• Asian-Australasian Journal of Animal Sciences
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• 제19권9호
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• pp.1217-1224
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• 2006

The registration data of 15 populations from nine major swine breeding farms were investigated to check levels of inbreeding and the current status of pedigree structures of breeding stocks. The average rate of inbreeding per generation was 0.208%, 0.209%, 0.098%, 0.307% and 0.071% for farms D, S, K, H, and Y in Duroc, 0.071%, 0.188%, 0.685%, 0.336%, and 0.449% for farms S, H, C, J, and W in Landrace, and 0.243%, 0.123%, 0.103%, 0.165%, and 0.286% for farms D, S, G, H, and J in Yorkshire, respectively. The average inbreeding rate was highest for Landrace, intermediate for Yorkshire, and lowest for Duroc farms. In Landrace and Yorkshire populations there were few immigrant animals per generation. In Duroc, however, there were quite large numbers of immigrant animals per generation compared to other breeds. The effective population sizes calculated from the average rate of inbreeding were distributed between 73.0 and 708.7. Specific values were 204.8, 239.7, 508.8, 163.0 and 708.2 for farms D, S, K, H, and Y in Duroc, 708.7, 266.5, 73.0, 148.9, and 111.3 for farms S, H, C, J, and W in Landrace, and 205.5, 406.0, 486.9, 302.6 and 175.0 for farms D, S, G, H, and J in Yorkshire, respectively. The values were acceptable for natural selection for fitness and inbreeding depression. The results showed that there was no cause for concern over the current inbreeding level of major swine breeding farm populations and the inbreeding level was within an acceptable range.

• Journal of Animal Science and Technology
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• 제56권8호
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• pp.31.1-31.9
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• 2014

The objective of this study was to describe the population structure and inbreeding, and to quantify their effects on weights at different ages of Mehraban sheep in Iran. The analysis was based on the pedigree information of 26990 animals and 10278 body weight records from birth to yearling age. Data and pedigree information were collected during 1994 to 2011 by the breeding station of Mehraban sheep. The population structure was analyzed using the CFC program. Inbreeding of all animals was calculated by INBUPGF90 program. All animals were grouped into three classes according to their inbreeding coefficients: the first class included non-inbred animals (F=0); and the second and third classes included inbred animals (0$F{\geq}0.05$, respectively). The average inbreeding in Mehraban sheep was 1.69%. Founder equivalent ($f_e$) values were estimated to be 4244, 3116 and 2965 during 1994-1999, 2000-2005 and 2006-2011, respectively. The effective population sizes ($N_e$) were 363, 5080 and 5740 during 1994-1999, 2000-2005 and 2006-2011, respectively. Generation interval was 2.15 years for this breed of sheep. Regression coefficients of birth weight, 3-month weight, 6-month weight and yearling weight on lamb inbreeding were estimated to be -6.340.69, -14.685.33, 48.009.43 and 98.6515.65, respectively. Both positive and negative inbreeding effects were found in the current study. The utilization of a program for designed mating system, in the present flock, could be a suitable approach to keep the level of inbreeding under control.

• Asian-Australasian Journal of Animal Sciences
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• 제28권9호
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• pp.1244-1251
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• 2015

A herd of Berkshire pigs was established in 2003 and subjected to selection without introduction of any genetic resources until 2007. The complete pedigree, including 410 boars and 916 sows, as well as the records from 5,845 pigs and 822 litters were used to investigate the results obtained from the selections. The index of selection for breeding values included days to 90 kg (D90kg), backfat thickness (BF) and number of piglets born alive (NBA). The average inbreeding coefficients of pigs were found to be 0.023, 0.008, 0.013, 0.025, 0.026, and 0.005 from 2003 to 2007, respectively. The genetic gains per year were 12.1 g, -0.04 mm, -3.13 days, and 0.181 head for average daily gain (ADG), BF, D90kg, and NBA, respectively. Breeding values of ADG, BF and D90kg were not significantly correlated with inbreeding coefficients of individuals, except for NBA (-0.21). The response per additional 1% of inbreeding was 0.0278 head reduction in NBA. The annual increase of inbreeding was 0.23% and the annual decrease in NBA due to inbreeding was 0.0064 head. This magnitude could be disregarded when compared with the annual gain in NBA (0.181 head). These results suggest that inbreeding and inbreeding depression on ordinary farms can be controlled with a proper breeding scheme and that breeding programs are economical and safe relative to the risks associated with importation of pigs.

• 한국작물학회지
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• 제28권4호
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• pp.473-480
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• 1983

육종자료를 얻기 이해 수집한 한국 재래종 옥수수 57계통에 대하여 주성분 분석법을 이용하여 계통분류를 행하고 분류된 계통군별로 주요특성에 대한 유전적 특성을 구명하고자 본 연구를 수행하였던 바 그 결과를 요약하면 다음과 같다. 1. 특성들의 평균치는 모든 특성에서 교배류형별로 차이가 있었는데 출수기까지의 일수를 제외한 모든 특성에서 자식된 계통의 것은 세력이 감소되었고 Top 교배된 계통의 것은 세력이 증대되었다. 2. 특성들의 자식열세 정도는 계통에 따라 차이가 있었으며 수량, 이삭중, 초장 등에서 비교적 크게 나타났고, 분류된 군별 자식열세 정도는 100립중, 엽수, 엽장, 출수기까지의 일수 등의 특성이 계통군 I에서 컸고 기타의 특성은 계통군 II에서 컸다. 3. 특성들의 잡종강세 정도는 계통간 차이가 있었으며 이삭중, 이삭립중, 수량, 100립중, 초장등에서 높았으며 분류된 군별로 보면 이삭길이, 이삭직경, 이삭중, 이삭당 립중, 100립중, 엽장 등의 특성은 계통군 II에서 높았고 기타의 특성은 계통군 I에서 높았다. 4. 특성들의 동질접합체 정도는 이삭중(79.1%)에서 가장 높았으며 이삭수(-2.1%)에서 가장 낮았는데 특성별로 큰 차이가 있었다. 분류된 군별에 있어서도 동질접합체 정도는 특성에 따라 차이가 있었는데 계통군 II에서 높은 것이 많았고 계통군 I에서는 낮은 것이 많았다. 5. 형매교배된 계통의 특성과 Top 교배된 계통의 특성과의 상관관계는 모든 특성에서 정의 상관을 나타내었으며 이삭수, 초장, 수량 등에서 높은 상관도를 보였으며 이삭직경, 100립중, 엽수 등에 따라서는 유의성이 인정되지 않았다.

• Asian-Australasian Journal of Animal Sciences
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• 제10권4호
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• pp.422-427
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• 1997

Breeding efficiency was investigated to reveal crucial factors for constructing effective breeding system with subdivided populations under equal genetic level. Simulation study of selection experiment was performed for 20 generations with 20 replications each, comparing average breeding values and inbreeding coefficients between the two breeding systems; single population scheme and two population scheme, each of which had the same genetic parameters. Genetic correlations (-0.5 to 0.5) were assumed to be caused only by pleiotropic effect of a gene. Phenotypes of the two traits generated by polygenic effect with additive 36 loci and residuals distributed normally were selected by two traits selection index procedure. Comparing between the single population scheme and the two population scheme, the single population scheme showed higher genetic gain with lower inbreeding coefficient. This result was confirmed particularly for the situation of high selection intensity, high heritability and high degree of unevenness for economic weight. Genetic correlations in the single population scheme were significantly lower than the two population scheme when initial genetic correlation was negative. When terminal crossbreeding for the two population scheme is taken into account, superiority of the two population scheme was suggested. The terminal crossbreeding was effective under the situation of long term selection, existence of moderate inbreeding depression and use of less extreme economic weight.

• Journal of Animal Science and Technology
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• 제62권6호
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• pp.777-789
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• 2020

Intense artificial selection has been imposed to Luzhong mutton sheep population in the past years. Improvements on growth and reproductive performance are two breeding goals in the present herd. Although some progresses were phenotypically observed possibly due to inbreeding induced by strong selection in terms of these traits, the genomic evaluation was poorly understood. Therefore, a high-density SNP array was used to characterize the pattern of runs of homozygosity (ROH), estimate inbreeding and inbreeding depressions on early growth performance and litter size based upon ROH, and scan positive selection signatures of recent population. Consequently, a low inbreeding level was observed which had negative effects on litter size, but not on early growth performance. And 160 genes were under selection, of which some were reported to be linked to several traits of sheep including body weight, litter size, carcass and meat quality, milk yield and composition, fiber quality and health, and the top genes were associated with growth (growth hormone [GH]- growth hormone receptor [GHR]- Insulin-like growth factor 1 [IGF1] axis) and litter size (bone morphogenic proteins [BMPs]-associated). The effectiveness of previous breeding measures was highlighted, but purging selection was proposed to alleviate the inbreeding depression on litter size, providing some genomic insights to breeding management of Luzhong mutton sheep.

• 한국작물학회지
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• 제25권3호
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• pp.21-30
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• 1980

수집된 재래종 옥수수 계통 가운데서 옥수수 육종에 이용할 수 있는 새로운 육종재료를 선발하고 유지하기 위하여 1978년에 각각 아매교배, 일대자식 그리고 Top-교배시킨 69계통에 대하여 옥수수의 주요특성을 조사비교하였던 바 그 결과를 요약하면 다음과 같다. 1. 초장은 계통간에 큰 차이가 있었는데 평균초장은 아매교배된 것이 155.0cm이었고 일대자식된 것은 141.8cm, Top-교배된 것은 210.0cm로 6.05%의 자식열세 및 40.0%의 잡종강세를 나타내었다. 2. 이삭길이는 계통간에 큰 차이가 있었고 교배처리에 따라서도 큰 차이를 보였는데 평균 이삭길이는 아매교배된 것이 14.1cm, 일대자식된 것이 11.6cm, Top-교배된 것이 18.1cm로 로 16.0%의 자식열세현상 및 18.1%의 잡종강세현상을 나타내었다. 3. 이삭직경은 평균적으로 아매교배된 것이 3.4cm, 일대자식된 것이 3.1cm, Top-교배된 것이 3.9cm로 8.7%의 자식열세 및 16.8%의 잡종강세를 보였다. 4. 이삭중은 계통간 변이폭이 컸으며 평균 이삭중은 아매교배된 것이 77.6gr이었고 일대자식된 것은 45.5gr, Top-교배된 것은 147.0gr으로서 41.3%의 자식열세 및 89.6%의 잡종강세를 나타내었다. 5. 이삭당 입중은 아매교배된 것이 평균 64.39gr, 일대자식된 것이 36.49gr, Top-교배된 것은 123.1gr으로서 교배처리에 따라 큰 차이가 있었으며 계통간에도 큰 차이가 있었다. 6. 이삭당 Cob중에 대한 입중비는 평균으로 아매교배된 것이 5.47, 일대자식된 것은 4.03, Top-교배된 것은 5.55로서 12.9%의 자식열세 및 13.1%의 잡종강세를 보였다. 7. 100입중은 계통간 차이가 있었으며 평균 100 입중은 아매교배된 것이 19.4gr, 일대자식된 것이 16.2gr, Top-교배된 것이 24.6gr으로서 15.3%의 자식열세 및 42.9%의 잡종강세현상을 보였다. 8. 재래종은 대조품종보다 흑수위축병에 대한 이병율이 낮았으며 10% 이하인 것도 10여 계통이나 발견되었다. 9. 웅수출현기는 교배처리에 따라서는 큰 차이가 없었고 재래종이 대조품종보다 2～3일 빨랐다. 10. 수집재래종 옥수수의 주당 이삭수는 평균 1.4개이었는데 교배처리간에는 큰 차이가 없었다. 착수절위는 평균 6절이며 교배처리간 약간의 차이가 있었다.