• Journal of Animal Science and Technology
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• v.44 no.6
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• pp.669-676
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• 2002

The efficiency of marker assisted selection(MAS) over conventional selection index based sorely on phenotypic records was studied by deterministic simulation model. Parameter combination of heritability and amount of genetic variation due to the markers included in the index was employed. For the index with own phenotypic information vs. the index with own phenotypic plus marker information, the relative efficiency of MAS over the selection with phenotypic records was about 38% high when heritability was low(0.05). However, when heritability was high(50%), the relative efficiency of MAS was vary low and almost negligible. For more practical situation of selection index which included information on own, sire and dam, MAS was less effective than when selection criteria was only on own performance.

• Journal of Ecology and Environment
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• v.36 no.3
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• pp.151-158
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• 2013

We estimated phenotypic selection on the height and number of flowering-stalks in a rosette annual Cardamine hirsuta by applying path analysis to the data collected at three natural populations located in central Japan. The path from rosette size was positively connected with the fruit production through the both height and number of flowering-stalks. In the all three populations, the paths from the number of stalks were more strongly connected with the fruit production than from the height of stalks. The paths from the rosette size showed similar magnitude with the number of stalks and the height of stalks. The direct path from rosette size to the fruit production was detected only at one site. These results suggest stronger phenotypic selection on the rosette size through the number of stalks than the height of stalks. The lateral branching rather than increment of individual inflorescence size is the major response to control the fruit production for C. hirsuta growing in a natural habitat.

• Journal of the Korean Society of Tobacco Science
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• v.3 no.1
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• pp.49-57
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• 1981

To obtain genetic information for breeding aromatic tobacco, broad sense heritabilities, phenotypic, and genotypic correlations were obtained for the following characters : days to frowert, plant height, number of leaves, leaf shape and nicotine. Six pure line varieties and the first and second generations of 5 crosses among them were employed in this study. The heritabilities for number of leaves and nicotine were very high in pure line varieties. However, the heritabilities for days to flower and yield were low in six varieties as well as in F2. Genotypic correlations had higher values than phenotypic did. Heritabilities calculated from segregating generations were lower than those from pure varieties, regardless of crosses involved. Positive phenotypic correlations between yield and plant height were observed in all crosses. Same phenomenon was observed with correlations between days to flower and number of leaves. The genotypic and phenotypic variances and covariances entering into the computation of correlations were used to construct the seletion indices for yield. The use and limitation of selection index was also discussed.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.12
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• pp.1912-1921
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• 2020

Objective: This study assessed genomic prediction accuracies based on different selection methods, evaluation procedures, training population (TP) sizes, heritability (h²) levels, marker densities and pedigree error (PE) rates in a simulated Korean beef cattle population. Methods: A simulation was performed using two different selection methods, phenotypic and estimated breeding value (EBV), with an h² of 0.1, 0.3, or 0.5 and marker densities of 10, 50, or 777K. A total of 275 males and 2,475 females were randomly selected from the last generation to simulate ten recent generations. The simulation of the PE dataset was modified using only the EBV method of selection with a marker density of 50K and a heritability of 0.3. The proportions of errors substituted were 10%, 20%, 30%, and 40%, respectively. Genetic evaluations were performed using genomic best linear unbiased prediction (GBLUP) and single-step GBLUP (ssGBLUP) with different weighted values. The accuracies of the predictions were determined. Results: Compared with phenotypic selection, the results revealed that the prediction accuracies obtained using GBLUP and ssGBLUP increased across heritability levels and TP sizes during EBV selection. However, an increase in the marker density did not yield higher accuracy in either method except when the h² was 0.3 under the EBV selection method. Based on EBV selection with a heritability of 0.1 and a marker density of 10K, GBLUP and ssGBLUP_0.95 prediction accuracy was higher than that obtained by phenotypic selection. The prediction accuracies from ssGBLUP_0.95 outperformed those from the GBLUP method across all scenarios. When errors were introduced into the pedigree dataset, the prediction accuracies were only minimally influenced across all scenarios. Conclusion: Our study suggests that the use of ssGBLUP_0.95, EBV selection, and low marker density could help improve genetic gains in beef cattle.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.4
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• pp.363-367
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• 1998

This study has objectives of to estimate the genetic and phenotypic trend for growth in a closed herd of Landrace $\times$ desi crossbreds. The possibility of early selection of boars was also investigated in order to reduce generation interval and thus, to enhance response per year in selection programmes. The data originated from Livestock Production Research (Pigs), Indian Veterinary Research Institute (IVRI), Izatnagar (UP), India - a unit of All India Coordinated research Project on Pigs (AICRP on Pigs). Data consisted of 891 crossbred piglets, progeny of 29 boars. The piglets were born in 132 parities of 72 sows between 8 years from 1987 to 1994. Records on weight at birth, at 2 weeks interval upto 8 weeks of age (Wl, W2, ${\cdots}\;{\cdots}$ W8) and at 16th week (W16) were used in this investigation. BLLTP estimates of the sires were computed. Breeding value of each sire was estimated as twice of sire and sire group solutions. Phenotypic trend was estimated as regression of weight performance on year. Genetic trend was computed by estimating regression of breeding value of sires on time. Average body weights ranged from 0.92 kg (W1) to 18.95 kg (W16) and showed a continuous increase over age. Heritabilities of the weight at 4th and 6th week were medium (0.29 and 0.14). Rest of the weights were highly heritable. The product moment and rank, both correlations were high between breeding value for W6 and W16 (0.68 and 0.70). This shows that sire selection for W6 can be successfully implemented in order to achieve sufficient genetic improvement in growth. Phenotypic trend was positive at all ages. The phenotypic regression coefficient ranged from 0.02 kg at birth to 0.40 kg at 16 weeks. Genetic trend was also positive. The regression coefficients of average breeding value of sires on time showed a range of 1.471 kg (0.021 to 1.492 kg) for different weights. These coefficients were significant and higher than their corresponding phenotypic regression coefficient.

• Journal of Aquaculture
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• v.13 no.1
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• pp.13-19
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• 2000

A genetic analysis of reproductive characters of masu salmon at three year classes was described. the reproductive performance of masu salmon spawning at 2 years of age was analyzed using data number fertility hatchability and growth traits to the juvenile stage. The phenotypic correlations among the traits were also estimated. it was determined that egg volume was the principle deter-minant of egg number and that the relationship of number to size was negative. It is recommended that selection for egg size be included in all selection programs and egg number be ignored in any welection program designed to increase body size. Phenotypic correlations between body size of parents and egg traits as well as between body size of offspring and egg traits were not significantly positive or negative magnitude at three year classes.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.1 no.1
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• pp.42-45
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• 1963

In a plant breeding program, an efficient selection of desired characters in a population is important. Generally, many agronomic characters in a given population are determined by polygenes and quantitatively inherited. In practice, the genetic relationship between two observed characters which are undoubtedly subjected to the environmental influence is difficult to identify. In recent years, many workers have attempted to understant the genetic relationship between characters in terms of genotypic correlation, and the knowledge thus gained should furnish many important and useful information for the planning of breeding, selection, and interpretation of the result. The genotypic correlation is the result of pleiotropy, linkage of genes(2, 3, 5, 6, 8) and natural or artificial selection(4). The purposes of this study were to estimate genotyric and phenotypic correlations between all possible pairs of nine characters. and to seek certain characters which may be useful as indicators of certain important agronomic characters. Weber and Moorthy(10), Johnson et al. (5) and Sheth(7) found that in general, the genotypic correlations were higher than the phenotypic correlations. Weiss et al. (11) obtained significant positive correlations between maturity and oil content, maturity and low protein content, and high protein content and low oil content. Weber and Moorthy(10) reported the positive genotypic correlations between flowering and maturity, yield and maturity, yield and plant height, yield and seed weight, and negative genotypic correlations between maturity and oil content, and oil content and seed weight. Johnson et al. (5) studied the genotypic and phenotypic correlations among 24 characters and concluded that selection based entirely on a long fruiting period, lateness, heavy seed, low protein, high oil and resistance to lodging would be effective in increasing yield. Sheth(7) found the following positive associations among characters; height and maturity, yield and lodging, low protein content and high oil content, and yield and low protein content. Hanson et al.(1) also reported high negative correlation between seed yield and protein content.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.5
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• pp.747-755
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• 2009

The feed resource for animals is a major cost determinant for profitability in livestock production enterprises, and thus any effort at improving the efficiency of feed use will help to reduce feed cost. Feed conversion ratio, expressed as feed inputs per unit output, is a traditional measure of efficiency that has significant phenotypic and genetic correlations with feed intake and growth traits. The use of ratio traits for genetic selection may cause problems associated with prediction of change in the component traits in future generations. Residual feed intake, a linear index, is a trait derived from the difference between actual feed intake and that predicted on the basis of the requirements for maintenance of body weight and production. Considerable genetic variation exists in residual feed intake for cattle and pigs, which should respond to selection. Phenotypic independence of phenotypic residual feed intake with body weight and weight gain can be obligatory. Genetic residual feed intake is genetically independent of its component traits (body weight and weight gain). Genetic correlations of residual feed intake with daily feed intake and feed conversion efficiency have been strong and positive in both cattle and pigs. Residual feed intake is favorably genetically correlated with eye muscle area and carcass weight in cattle and with eye muscle area and backfat in pigs. Selection to reduce residual feed intake (excessive intake of feed) will improve the efficiency of feed and most of the economically important carcass traits in cattle and pigs. Therefore, residual feed intake can be used to replace traditional feed conversion ratio as a selection criterion of feed efficiency in breeding programs. However, further studies are required on the variation of residual feed intake during different developmental stage of production.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.9
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• pp.1242-1246
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• 2003

Data pertained to 335 crossbred cows comprising of 1/2 Friesian (F) + 1/2 Hariana (H), 1/2 F + 1/4 Jersey (J) + 1/4 H, 1/2 F + 1/4 Brown Swiss (BS) + 1/4 H, 1/2 F + 1/4 Red Dane (R) + 1/4 H, FR (I) and FRH (I) genetic groups extending over a period of 21 years (1970-1990) maintained at Animal Farm of CCS HAU, Hisar. The averages for first lactation milk yield was $2,486.24{\pm}80.26kg$ and peak yield of first three lactation were $11.35{\pm}0.72kg$, $13.97{\pm}0.60kg$ and $16.02{\pm}0.42kg$, respectively. The lifetime milk production was observed as $11,305.16{\pm}1,004.52kg$ in crossbred cattle. The average first lactation fat yield was observed as $102.06{\pm}0.01kg$ and peak fat yield of first three lactation were $0.458{\pm}0.01$, $0.490{\pm}0.01$ and $0.500{\pm}0.02kg$, respectively. The lifetime fat production was estimated as $502.31{\pm}45.90kg$. LTMP and LTFP had reasonably good additive genetic variance which could be exploited either through mass selection/combined with family or pedigree selection. FLMY, peak yields and LTMP had significant positive phenotypic correlation with FLFY and LTFP and the correlation at the genetic level were also higher and positive for these traits. Finally, peak week milk yield of first lactation (PMY1) was the earliest available trait having desirable and significant correlation at phenotypic and positive at genetic level with FLFY, PFY1 and PFY2, PFY3 and LTFP and selection for this trait will help in early evaluation of sires and dams and will increase genetic advancement per unit of time.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.4
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• pp.478-483
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• 2008

Records of a Northeastern Thai indigenous cattle line population were used to estimate genetic parameters and annual trends for calf weights. The data set comprised records of 1,922 and 1,489 animals for birth and weaning weight, respectively born from 1993 to 2004. A bivariate analysis was carried out for variance and covariance components estimations using average information restricted maximum likelihood procedure. Average estimated breeding value and maternal breeding value of the animals born in 1993 were set to zero as a base group. Genetic trends of each trait were calculated by regressing average estimated breeding values and maternal breeding values on birth year of calves. Phenotypic trends for each trait were calculated by regressing the yearly adjusted weight on birth year of calves. The results revealed that the estimate of direct heritability, maternal heritability and maternal permanent environmental variance as a proportion of phenotypic variance for birth and weaning weight was 0.40, 0.14 and 0.04; 0.27, 0.05 and 0.23, respectively. Direct heritability was moderately heritable and genetic improvement through selection can be achieved. The estimate of phenotypic, direct genetic, maternal genetic and maternal permanent environmental correlation between birth and weaning weight was 0.48, 0.65, 0.98 and 0.73, respectively. The phenotypic trend, genetic trends of estimated breeding value and maternal breeding value for birth weight was 0.18, 0.04 and 0.01 kg/year, respectively. The phenotypic trend, genetic trends of estimated breeding value and maternal breeding value for weaning weight was -1.36, 0.32 and 0.03 kg/year, respectively. As maternal genetic effect was considerably less important than direct genetic effect, selection for improved weaning weight of this Northeastern Thai indigenous cattle line can place more emphasis on the direct genetic effect.