• Journal of Korean Society of Forest Science
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• v.72 no.1
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• pp.16-26
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• 1986

Allozyme study on a small pitch pine stand originating and expanded rather rapidly from a few founder trees indicated that the colonization of the pitch pine population was made progressively from the place where the founder trees located to another by moving in cohorts of seeds from a limited number of family or genetically closely related family groups in line with the succeeding generations. This pattern of migration and colonization resulted marked differences in allelic and genotypic frequencies at many of the allozyme loci between the initially colonized subpopulation on the south-facing slope and the lately colonized subpopulation on north-facing slope of a hill. It appeared that gene fixation due to inbreeding and genetic drift occurred at some loci in the pitch pine population or subpopulations. However, even in t 1e inbreeding small pitch pine population or subpopulations, a comparatively large amount of genetic diversity or heterozygosity was maintained due to the high levels of gene recombination at many of the gene loci and natural selections favoring for heterozygotes.

• Animal Bioscience
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• v.36 no.5
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• pp.692-703
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• 2023

Objective: The main goals of this investigation were to i) assess the population structure and genetic diversity and ii) determine the efficiency of the ongoing breeding program in a closed flock of Angora rabbits through pedigree analysis. Methods: The pedigree records of 6,145 animals, born between 1996 to 2020 at NTRS, ICAR-CSWRI, Garsa were analyzed using ENDOG version 4.8 software package. The genealogical information, genetic conservation index and parameters based on gene origin probabilities were estimated. Results: Analysis revealed that, 99.09% of the kits had both parents recorded in the whole dataset. The completeness levels for the whole pedigree were 99.12%, 97.12%, 90.66%, 82.49%, and 74.11% for the 1st, 2nd, 3rd, 4th, and 5th generations, respectively, reflecting well-maintained pedigree records. The maximum inbreeding, average inbreeding and relatedness were 36.96%, 8.07%, and 15.82%, respectively. The mean maximum, mean equivalent and mean completed generations were 10.28, 7.91, and 5.51 with 0.85%, 1.19%, and 1.85% increase in inbreeding, respectively. The effective population size estimated from maximum, equivalent and complete generations were 58.50, 27.05, and 42.08, respectively. Only 1.51% of total mating was highly inbred. The effective population size computed via the individual increase in inbreeding was 42.83. The effective numbers of founders (f_e), ancestors (f_a), founder genomes (f_g) and non-founder genomes (f_ng) were 18, 16, 6.22, and 9.50, respectively. The fe/fa ratio was 1.12, indicating occasional bottlenecks had occurred in the population. The six most influential ancestors explained 50% of genes contributed to the gene pool. The average generation interval was 1.51 years and was longer for the sire-offspring pathway. The population lost 8% genetic diversity over time, however, considerable genetic variability still existed in the closed Angora population. Conclusion: This study provides important and practical insights to manage and maintain the genetic variability within the individual flock and the entire population.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.6
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• pp.755-765
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• 2013

The accumulation of inbreeding and the loss of genetic diversity is a potential problem in the modern swine breeds in China. Therefore, the purpose of this study was to analyze the pedigrees of Chinese Duroc (CD), Landrace (CL) and Yorkshire (CY) swine to estimate the past and current rates of inbreeding, and to identify the main causes of genetic diversity loss. Pedigree files from CD, CL and CY containing, 4529, 16,776 and 22,600 records, respectively, were analyzed. Pedigree completeness indexes of the three breeds, accounting for one generation back, were 83.72, 93.93 and 93.59%, respectively. The estimated average annual inbreeding rates for CD, CL and CY in recent three years were 0.21, 0.19 and 0.13%, respectively. The estimated average percentage of genetic diversity loss within each breed in recent three years was about 8.92, 2.19, and 3.36%, respectively. The average relative proportion of genetic diversity loss due to unequal contributions of founders in CD, CL and CY was 69.09, 57.95 and 60.57%, and due to random genetic drift was 30.91, 42.05 and 39.43%, respectively. The estimated current effective population size for CD, CL and CY was 76, 117 and 202, respectively. Therefore, CD has been found to have lost considerable genetic diversity, demanding priority for optimizing the selection and mating to control future coancestry and inbreeding. Unequal contribution of founders was a major cause of genetic diversity loss in Chinese swine breeds and random genetic drift also showed substantial impact on the loss of diversity.

• Korean Journal of Agricultural Science
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• v.42 no.2
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• pp.141-149
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• 2015

The data of Duroc swine species that were born from 2000 to 2014 excluding missing ones collected by Korea National Institute of Animal Science were used in the present study. After removing missing data we used 9756 of productions data and 1728 of reproductive reference of breeding research to study the level of inbreeding and to investigate the impact on the reproductive traits, production traits. The correlation of reproductive traits and inbreeding coefficient are -0.07, -0.08 for total number pigs born, number of pigs born alive respectively and birth weight per litter is -0.10, number of pigs born alive per litter to 21days is -0.06 and body weight per litter to 21days is -0.09. The correlation coefficients of the inbreeding coefficients of reproductive traits are shown within 10% with negative correlation (P < 0.05). Days of 90kg and Backfat in the correlation coefficient and inbreeding coefficient production traits were not observed significant correlations, Average daily gain was investigated by the positive correlation of 0.05. According to the above results, the inbreeding level gave a negative effect on the improvement of the breed traits, investigating a relatively high compared to a negative effect on other traits. But overall correlation degree is less than 10% was observed. This inbreeding coefficient has not been clearly observed due to degeneration of the average inbreeding coefficients of these generations was maintained within 10% of the population. The scale of the experimental group was about 150 degree pig husbandry is very small compared to the advanced countries. However, the level of inbreeding in the population group with the appropriate mating combinations is maintained below 10% of population is thought to be small and can minimize the effects of inbreeding degeneration. further testing utilizing this selection is constantly considered to be necessary.

• Journal of Sericultural and Entomological Science
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• v.31 no.1
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• pp.20-24
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• 1989

The purpose of this experiment was to obtain the basic information on heterosis and inbreeding depression of quantitative characters in the silkworm by diallel crosses of seven varieties differing widely in each character. Period of 5th instar cocoon weight, cocoon layer weight, cocoon layer ratio, boiling off ratio, raw silk percent, bave length, bave weight, bave size, weight of first molting larva and fourth molting larva were investigated. The results obtained were summarized as follows : The degrees of positive heterosis of cocoon weight and cocoon layer weight were higher. Period of 5th instar and boiling off ratio were negative heterosis. In F1 generation, cocoon weight and bave weight showed positive heterobeltiosis, while fifth instar-period, cocoon layer ratio and boiling off ratio showed negative heterobeltiosis in the F1 and F2 generation. Inbreeding depression was observed in cocoon layer ratio and boiling off ratio.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.8
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• pp.1063-1072
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• 2012

Effective population size ($N_e$) is an important measure to understand population structure and genetic variability in animal species. The objective of this study was to estimate $N_e$ in Sapsaree dogs using the information of rate of inbreeding and genomic data that were obtained from pedigree and the Illumina CanineSNP20 (20K) and CanineHD (170K) beadchips, respectively. Three SNP panels, i.e. Sap134 (20K), Sap60 (170K), and Sap183 (the combined panel from the 20K and 170K), were used to genotype 134, 60, and 183 animal samples, respectively. The $N_e$ estimates based on inbreeding rate ranged from 16 to 51 about five to 13 generations ago. With the use of SNP genotypes, two methods were applied for $N_e$ estimation, i.e. pair-wise $r^2$ values using a simple expectation of distance and $r^2$ values under a non-linear regression with respective distances assuming a finite population size. The average pair-wise $N_e$ estimates across generations using the pairs of SNPs that were located within 5 Mb in the Sap134, Sap60, and Sap183 panels, were 1,486, 1,025 and 1,293, respectively. Under the non-linear regression method, the average $N_e$ estimates were 1,601, 528, and 1,129 for the respective panels. Also, the point estimates of past $N_e$ at 5, 20, and 50 generations ago ranged between 64 to 75, 245 to 286, and 573 to 646, respectively, indicating a significant $N_e$ reduction in the last several generations. These results suggest a strong necessity for minimizing inbreeding through the application of genomic selection or other breeding strategies to increase $N_e$, so as to maintain genetic variation and to avoid future bottlenecks in the Sapsaree population.

• Journal of Life Science
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• v.17 no.11
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• pp.1477-1481
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• 2007

The mating systems of natural populations of Vicia tetrasperm in Korea were determined using allozyme analysis. The result suggests that V. tetrasperm is low rates of outcrossing or mix-mating outcrossing (self-fertilization, s < 0.5). At the population levels, the values of inbreeding coefficient of ten populations in Korea varied from 0.131 to 0.176, giving an average 0.154. For ten natural populations, multi-locus estimates of outcrossing (tm) was 0.333 across fifteen polymorphic loci, with individual population values ranging from 0.269 to 0.423. The differences between the tm and ts values were not close to zero (tm - ts > 0.154), indicating that biparental inbreeding was significant in the loci. The reason for relatively low outcrossing rates of some populations could be attributed to extensive consanguineous mating and isolation of flowering mature plants. Although heterozygote excess was observed in one natural population, most populations exhibited varying degrees of inbreeding and heterozygotes deficit. Thus, selection against homozygotes operated in the progeny populations throughout the life cycle.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.4
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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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• v.55 no.5
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• pp.367-371
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• 2013

This study was carried out to estimate the average inbreeding coefficients and effective population size (EPS) and to seek alternatives on the problems of Holstein cattle in Korea. The data used in this study was obtained from the Korean Animal Improvement Association (KAIA) and 635,268 heads of Holstein records out of 1,872,195 Holstein registration data were used for the analysis. The average inbreeding coefficients were estimated at a range of 0.11 to 1.07%. The average inbreeding coefficients at the $14^{th}$, $19^{th}$ and $22^{nd}$ generation were estimated at 0.43%, 0.92% and 1.07%, respectively. The estimated inbreeding coefficients within the range of 0%, 0 to 6.25%, 6.25 to 12.5%, 12.5 to 25%, and >25% were observed in 50.5%, 48.3%, 0.8%, 0.1%, and 0.3% of the animals, respectively. The estimated effective population size (EPS) was 619 heads from the $8^{th}$ to $22^{nd}$ generation, and 922 heads from the $19^{th}$ to $22^{nd}$ generation.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.1
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• pp.1-6
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• 2004

The 490 and 380 performance records of Karan Fries and Karan Swiss cows developed through crossbreeding followed by inter-se mating were evaluated for production, reproduction performance and disposal rate. Duration of study (1982-92) was grouped into five periods (1982-83; 1984-85; 1986-87; 1988-89; 1990-92) and each year was divided into four seasons (Winter: Dec.-Jan.; Spring: Feb.-March; Summer: April-June; Rainy: July-Sept.; Autumn: Oct.-Nov). Data were also classified according to sire and level of inbreeding. The least squares means of FLY (first lactation yield -305 days), FLL (first lactation length), FSP (first service period), FDP (first dry period), FCI (first calving interval ), MY/FLL (milk yield per day of first lactation length), MY/FCI (milk yield per day of first calving interval), EBV (expected breeding value) and EBE (expected breeding efficiency) were $3,173{\pm}82$ kg, $34611{\pm}$days, $143{\pm}11$ days, $75{\pm}6$ days, $423{\pm}11$ days, $10.6{\pm}0.2$ kg, $8.9{\pm}0.2$ kg, $3,380{\pm}26$ kg, and $88.2{\pm}1.3$% respectively in Karan Fries. Corresponding estimates in Karan Swiss cows were $2,616{\pm}82$ kg, $328{\pm}8$ days, $148{\pm}12$ days, $103{\pm}9$ days, $435{\pm}13$ days, $8.9{\pm}0.2$ kg, $7.2{\pm}0.3$ kg, $2,924{\pm38}$ kg and $86.0{\pm}3.8$% respectively. The effect of sire was significant on FLY, MY/FLL, MY/FCI and EBV in both the herd (p<0.01). The 10 and 15% sires showed superiority (FLY) over herd average of 11 and 7% in Karan Fries and 32 and 21% in Karan Swiss cattle respectively. Inbreeding has adversely and significantly (p<0.05) affected the FLY, MY/FLL, MY/FCI and survivability of Karan Fries females; FDP and disposal through culling of Karan Swiss heifers. The Karan Fries heifers with inbreeding above 12.5% performed 16% lower FLY to herd average. The effect of season of calving was significant on FLL, FSP and FCI (p<0.05) in Karan Fries. Summer calvers ($361{\pm}12$) were have higher lactation length and autumn calvers ($329{\pm}14$) had minimum. Period of calving significantly influenced the FSP, FCI, MY/FLL and MY/FCI in Karan Fries and FLY, MY/FLL and MY/FCI in Karan Swiss. Production efficiency traits in Karan Fries herd witnessed higher yield in the last two periods whereas, Karan Swiss heifers showed fluctuating performance. The findings suggested judicious use of available genetic variability, keeping of inbreeding under safer level and managemental interventions for the consistent improvement of both herds.