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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.
To investigate the influences of candidate genes on the birth weight and the early stages of life, genotyping of the prolactin receptor 3(PRLR3) and retinol-binding protein 4(RBP4) genes was performed in 156 and 141 Berkshire pigs, respectively. The frequency of both PRLR3 alleles A and a was 0.50. The frequencies of the RBP4 alleles B and b were 0.42 and 0.58, respectively. Neither locus was in Hardy-Weinberg equilibrium. No significant associations of the PRLR3 alleles with birth or weaning weights and of the RBP4 alleles with birth weight were observed. The proportions of the phenotype variances due to the genotypes of PRLR3 in the feeder weights was 4.0% and those of RBP4 in the weaning and feeder weights were 11.9 and 3.3%, respectively(P<0.05). The dominance effect of PRLR3 and RBP4 on feeder weights was 2.40 and -1.86kg, respectively(P< 0.01). The additive and dominance effects of RBP4 on weaning weights were 0.332 and -0.682kg, respectively(P<0.01). Even if no significant epistasis of PRLR3 and RBP4 was detected, a considerable trend of consistent positive epistasis estimates of AA/BB and Aa/Bb was observed for all traits. The results of this study may have a considerable impact on early-stage growth by both loci, and a selection strategy should be designed separately for each marker in Berkshire pigs.
Herd, calving year and season have relatively highly variable effects on milk production traits of dairy cattle and seem to be suitable with the characteristics of random effect. For a statistical approach to estimate these effects, computational ease in estimating fixed contemporary group effects and accuracy in estimating random contemporary group effects for small numbers of observations in groups should be compared. For a genetic evaluation with small herd sizes and the relatively small registered and tested dairy cattle population in Korea. the contemporary group effects should be treated as random and the flexible grouping strategy insuring maximization of homogeneiety in subgroups would be a proper choice, because of accurate prediction of additive genetic effect is and less of a loss of information from records.
본 연구는 1995년부터 2001년까지 한국종축개량협회가 전국 종돈장으로부터 수집한 Landrace, Yorkshire 및 Duroc의 등지방 두께, 일당증체량, 90㎏ 도달일령, 등심단면적, 정육률, 총산자수 및 복당생존자돈수에 대해 유전적 그룹을 통한 품종효과의 추정과 유전능력 평가를 위하여 96,842두의 산육능력성적과 90,396복의 산자능력자료를 분석하였다. 추정된 품종효과들은 각 품종의 특징을 보여주는데 Landrace는 등지방, 정육률 및 총산자수에서 우수하였고, Yorkshire는 정육률, 등심단면적, 총산자수 및 복당생존자돈수에서 좋은 결과를 보여주었으며, Duroc은 90㎏ 도달일령과 일당증체량에서는 우수하였지만 가식부위를 결정하는 등지방 두께와 정육률, 번시능력을 보여주는 산자수에서 다른 품종에 뒤지는 것으로 나타났다. 유전적 그룹을 통한 품종효과의 추정으로 품종별로 능력평가를 하는 노력을 절감할 수 있고 또한 F1 잡종돈이 포함되어도 평가할 수 있다. This study was carried out for the simultaneous genetic evaluation of swine breeds from the seedstock farms in Korea. The performance tasted production records of 96,842 heads and the litter records of 90,396 litters from 1995 to 2001 were analyzed to estimate the breeding values and the breed effects of days to 90㎏, daily gain, back fat thickness, loin muscle area, lean meat percent, total litter size and number born alive from Landrace, Yorkshire and Duroc. Estimated breed effects of traits had shown the characteristics of the breeds. Landrace was superior in back fat thickness and lean meat percent to other breeds. Yorkshire had shown good performance in lean meat percent, loin muscle area, total litter size and number born alive. Duroc was superior to the other breeds in days to 90㎏ and daily gain. Conclusively, the multi-breed genetic evaluation would result in higher connectedness and provide convenience for the routine genetic evaluation process of swine performance and reproduction test.