• Asian-Australasian Journal of Animal Sciences
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• v.15 no.12
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• pp.1776-1783
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• 2002

A population segregating for the naked neck (Na) gene was used to evaluate its effect on fast growing broilers at heat stress. An experimental stock comparable to those of modern broilers was established by backcrossing to colour synthetic male and female lines. Matings between heterozygous (Na/na) males and females produced normally feathered (na/na), heterozygous (Na/na) and homozygous (Na/Na) chicks for the present study. Day old to seven week old coloured broilers of three genotypes viz. normally feathered (na/na), heterozygous naked neck (Na/na) and homozygous naked neck (Na/Na) were compared for heat dissipation, growth performance, body conformation traits, blood biochemical parameters and carcass traits in tropical climate. In hot climate, naked neck broilers had significantly less body temperature and better heat dissipation capabilities as compared to normal broilers. The naked neck broilers had significantly higher body weight and better feed conversion ratio than na/na broilers. The Na/Na or Na/na broilers exhibited higher giblet yield, blood loss and lower feather mass compared to na/na broilers. The results indicated that the reduction in feather coverage in Na/Na and Na/na broilers facilitates better heat dissipation with lower body temperature, more body weight gain, better FCR and carcass traits compared to normal broilers.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.59.1-59.1
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• 2011

We report the HST pixel analysis results of the interacting S0 galaxy, NGC 5195 (M51B), using the HST/ACS images in the F435W, F555W and F814W (BVI) bands. After 4x4 binning of the HST/ACS images to secure sufficient signal-to-noise ratio for each pixel, we derive several quantities describing the pixel color-magnitude diagram (pCMD) of NGC 5195, such as blue/red color cut, red pixel sequence parameters, blue pixel sequence parameters and blue-to-red pixel ratio. Those parameters reflect the internal properties of NGC 5195 like age, metallicity, dust content and galaxy morphology. To investigate the spatial distributions of stellar populations, we divide pixel stellar populations using the pixel color-color diagram and population synthesis models. As a result, we find that the tidal interaction with NGC 5194 significantly affects the stellar populations in their dust content and mean stellar age.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.557-562
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• 2002

This study was to estimate population growth parameters of the freshwater bivalve, Corbicula (Corbiculina) papyacca (Heude) in Korea. Samples were collected from Jojong stream in Chungpyeong from September 1999 to August 2000. Ages were determined from the ring of shell, The shell length of the samples ranged from 4,2 mm to 28.1 mm, The ring on the surface of shell was formed once a year from January to March, Marginal increment analysis of shell rings indicated that annuli were formed in June. Spawning period was estimated to be May to August with a peak between June and July through fatness analysis, and thus rings were considered to be true annual marks. Von Bertalanffy's growth parameter were estimated from a nonlinear method with the value of logical maximum shell length ($L_{propto}$) was 34,36 mm, K was 0.1531/year, logical age of shell length 0 ($t_{0}$) was -0,5246 year, and logical maximum total weight ($W_{propto}$) was 11.42 g.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.5
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• pp.636-642
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• 2018

Objective: The objective of this study was to estimate genetic parameters of milk, fat, and protein yields within and across lactations in Tunisian Holsteins using a random regression test-day (TD) model. Methods: A random regression multiple trait multiple lactation TD model was used to estimate genetic parameters in the Tunisian dairy cattle population. Data were TD yields of milk, fat, and protein from the first three lactations. Random regressions were modeled with third-order Legendre polynomials for the additive genetic, and permanent environment effects. Heritabilities, and genetic correlations were estimated by Bayesian techniques using the Gibbs sampler. Results: All variance components tended to be high in the beginning and the end of lactations. Additive genetic variances for milk, fat, and protein yields were the lowest and were the least variable compared to permanent variances. Heritability values tended to increase with parity. Estimates of heritabilities for 305-d yield-traits were low to moderate, 0.14 to 0.2, 0.12 to 0.17, and 0.13 to 0.18 for milk, fat, and protein yields, respectively. Within-parity, genetic correlations among traits were up to 0.74. Genetic correlations among lactations for the yield traits were relatively high and ranged from $0.78{\pm}0.01$ to $0.82{\pm}0.03$, between the first and second parities, from $0.73{\pm}0.03$ to $0.8{\pm}0.04$ between the first and third parities, and from $0.82{\pm}0.02$ to $0.84{\pm}0.04$ between the second and third parities. Conclusion: These results are comparable to previously reported estimates on the same population, indicating that the adoption of a random regression TD model as the official genetic evaluation for production traits in Tunisia, as developed by most Interbull countries, is possible in the Tunisian Holsteins.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.3
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• pp.234-243
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• 2000

This paper is to study population ecological characteristics, including growth parameters, survival rate, instantaneous coefficients of natural and fishing mortalities, and age at first capture of the soft-shelled clam, Mya japonioa in the intertidal zone of South Sea in Korea. For describing growth of the clam a von Bertalanffy growth model was adopted, The von Bertalanffy growth curve had an additive error structure and the growth parameters estimated from a non-linear regression were SH/sub ∞/=79.83mm, K=0.26, and t/sub 0/= -0.01. Survival rate (S) of the soft-shelled clam was 0.26 (SD=0.02). The instantaneous coefficients of natural mortality (M) was estimated to be 0.78/year and fishing mortality (F) 0.57/year for the soft-shelled clam. The age at first capture (t/sub c/) was estimated as 2.69 year. The mean densities of the soft-shelled clam by bottom type were 3.40 inds./m²(SE=0.18) in the sand, 63.4 inds./m²(SE= 0.53) in the muddy sand, and 0 inds./m2 (SE=0) in the gravelly sand. The mean densities of the soft-shelled clam by 3 different areas were 4.88 inds./m²(SE=0.09), 2.61 inds./m²(SE=0.13), 7.20 inds./m²(SE=0.18), respectively and the biomass of the clam were estimated as 131mt, 121mt, 665mt, respectively. An yield-per-recruit analysis showed that the current yield-per-recruit of about 8.30g with F=0.57/year and the age at first capture (t/sub c/) 2.69 year, was lower than the maximum possible yield-per-recruit of 9.60g. Fixing to at the current level and increased fishing intensity (F) could produce an increase in the predicted yield-per-recruit from 8.30g to about 9.40. However, estimated yield-per-recruit increased to 1.30g by decreasing to from the current age (2.69 year) to age two with F fixed at the current level. Yield-per-recruit was estimated under harvest strategies based on F/sub max/ and F/sub 0.1/.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1629-1629
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• 2001

The knowledge of the nutrition in animal production is difficult to assess due of difficulty to determine the amount and quality of feeds intake, mainly if forages are the most important compound in the diet. It must be able to know responses to the metabolic process in lactating dairy cows earring out feeds evaluation trials. These metabolism studies with cows, requires measurements of: I) The amount of all feeds consumed. II) Excretion of faeces. III) Excretion of urine. Taking as a basis these trials, forage and total intake, dietary digestibility and balances of nitrogen and energy can be calculated. However, these feeds evaluation experiments with animals are very time consuming and expensives. The faeces excreted by animals containt undigested residues of the diet consumed. For this reason, their analysis can be an successful tool to determine the amount and quality of feed intake and other important biological parameters. The aim of this work was to know if faeces analysis by NIR could be used to determine with enough accuracy some attributes of different lactating dairy cows diets, using a global equation, developed on an heterogeneus population. For this purpose a total of 79 faecal samples from eight grass, three grass silages and two maize silages metabolic trials, on six cows each one, were used to constitute the initial population. The calibration equations were developed to predict forage and total intake, organic matter digestibility, digestibility coefficient of crude energy and digestibility energy. The combination of several trials with different diets and animal conditions gave promising results.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.1
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• pp.29-36
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• 1992

This paper deals with the estimation of population ecological parameters, including growth parameters, survival rates, instantaneous coefficient of natural mortality and age at first capture, of the small yellow-croaker, Pseudosciaena Polyactis in Korean waters, which determine fluctuations in stock abundance. For describing the growth of the small yellow croaker, von Bertalanffy growth equation was recommended for the purpose of stock assessment, although the Gompertz model yielded the closest fit. The survival rate (S) of the croaker was estimated to be 0.219 (variance=0.0000262), and the instantaneous coefficient of natural mortality (M) was 0.4 $year^{-1}$. From the estimates of S and M, the instantaneous coefficient of fishing mortality (F) was calculated to be 1.11$year^{-1}$ implying an impact from fishing three times that of natural mortality. Finally, the age at first capture $(t_{c})$ was estimated to be 0.602.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.6
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• pp.747-753
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• 2001

In this study, the Italian milk recorded buffalo population from 1974 to 1996 was analysed with the purpose to estimate genetic and environmental variability and provide genetic parameters for the most important economic traits. High variability between herds was evident due to the poor knowledge of feeding requirements and husbandry technology in this species compared to cattle. Age at first calving was reduced by 57 days during the considered years following efforts made in better feeding and management from 1990; on the contrary, calving interval has increased by 17 days as a consequence of forcing buffaloes to calve in spring, in order to have the peak milk yield when milk is much better paid. Average milk yield increased by 1853 kg during these years, while lactation duration was reduced by 30 days. Season of calving has no effect on all traits. Calving order has a positive effect on milk yield especially because older cows produce more milk in shorter lactations. Heritability for the age at first calving and calving interval was 0.26 and 0.05 respectively. Heritability of productive traits, milk yield and duration of the lactation was 0.19 and 0.13 respectively, with repeatabilities of 0.40 and 0.26. Genetic trend for milk yield was 2.1 kg milk/year for the bulls and 1 kg for all population. The high genetic variability of milk production as well as duration of the lactation, indicates that there are good opportunities for genetic improvement when including these traits in a selection scheme. The low genetic trend registered over 15 years of recording activity can be explained by the fact that neither progeny testing was performed or selection schemes were implemented, due to the difficulties to use artificial insemination in buffalo.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.4
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• pp.380-385
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• 2002

The sand shrimp, Crangon hakodatei commonly occured in the southern coast of Korea. The population structure, growth, mortality, and size at sexual maturity of C. hakodatei were examined by the samples collected from the coastal area of Geoje Island, Korea from October 2000 to October 2001. For estimation of parameters of growth and mortality, monthly length-frequency data were analysed by ELEFAN. Parameters of growth were estimated, using the modified yon Bertalanffy growth function model. The female grew faster and reached larger size at the same age than the male, There was a breeding season showing a peak in winter (January to february). Total mortality by length-converted catch curve was estimated at $3.10 yr^{-1}$, fishing mortality was $0.62 y^{-1}$ and natural mortality was $2.48 yr^{-1}$. The size at $50\%$ sexual maturity for the female ranged from CL 11.00 to 11.50 mm.

• The Korean Journal of Community Living Science
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• v.28 no.4
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• pp.561-579
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• 2017

The rural elderly population has social capital based on regionalism and kinship, which acts as a positive function in terms of their self-efficacy. Self-efficacy refers to the belief in one's own abilities. In general, elderly people with high self-efficacy maintain a healthy life and age successfully. This study examines how the rural elderly population perceive their self-efficacy and social capital and analyzes the role of social capital as a mediating variable. Social capital consists of 4 aspects; trust, norms, network and participation. For this study, data were gathered from 344 rural elderly people aged 60 years and over. The results of this study were as follows. According to the analysis of the structure equation modeling effect, the direct effect of subjective health status on self-efficacy, the indirect effect of the parameters of norms and the total effect were all statistically significant. Second, the direct effect of adult children's support on self-efficacy was significant, and the indirect effects of the parameters of trust, norms and total effect were all statistically significant. This study confirmed that social capital has a mediating effect on the relationship among the subjective health status of the rural elderly, adult children's support and self-efficacy. Furthermore, social capital had a positive impact on the self-efficacy of the rural elderly. Based on these results, a policy for making use of the social capital of the rural elderly should be developed.