• Journal of Nutrition and Health
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• v.55 no.1
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• pp.10-20
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• 2022

This article evaluated levels of Estimated Average Requirements (EARs), Reference Nutrient Intakes (RNIs), and Acceptable Macronutrient Distribution Ranges (AMDRs) of protein using the recently revised Dietary Reference Intakes (DRIs) for Koreans (2020). Dietary protein requirements are based on amounts sufficient to satisfy physiological demands to accomplish nitrogen equilibrium. The same principle was applied to estimate EARs and RNIs, for adults in DRIs conducted in 2015 and 2020 in Koreans. EAR was estimated to be 0.73 g/kg body weight/day, according to data (0.66 g/kg body weight/day) obtained using the nitrogen balance method and adjusted by efficiency of protein use (90%). RNI was calculated as EAR increased by an amount equal to twice the standard deviation of an age group so as to cover 97.5% of the group and was found to be 0.91 g/kg body weight/day. For weaned infants, children, and adolescents, growth requirement was added to estimate EAR. In particular, growth requirement was adjusted by efficiency of protein use in the revised EAR, which led to higher EARs for weaned infants, children, and adolescents of both genders as compared with 2015 DRIs. The AMDR for protein was set at 7%-20% of energy intake, which was the same as 2015 DRIs. Current, average protein intake by the Korean population is almost twice times the EAR, which suggests it might be better to increase the minimal margin for AMDR. However, it was not adjusted in this revision due to lack of evidence.

• Fisheries and Aquatic Sciences
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• v.17 no.4
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• pp.455-459
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• 2014

A feeding trial was conducted to determine the optimum dietary protein requirement of young far eastern catfish Silurus asotus. Five isocaloric diets were formulated to contain graded levels of protein (35, 40, 45, 50, and 55%). Triplicate groups of fish (initial body weight of 44 g) were hand-fed to apparent satiation for 9-weeks. Weight gain and specific growth rate of fish fed 55% protein diet were significantly higher than those of fish fed 35 and 40% protein diets, but not significantly different from those of fish fed 45 and 50% protein diets. The feed efficiency of fish fed 50 and 55% protein diets was significantly higher than that of fish fed 35, 40 and 45% protein diets. The protein efficiency ratio of fish fed 40% protein diet was significantly higher than that of fish fed 45, 50 and 55% protein diets, but not significantly different from that of fish fed 35% protein diet. The dietary protein level significantly affected whole body lipid and moisture contents. The results of this study suggest that the 45% protein in the diet is optimal for maximum growth of young far eastern catfish weighing in the range of 44 to 227 g.

• Korean Journal of Rural Living Science
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• v.9 no.1
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• pp.33-42
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• 1998

The purpose of this study was to find out the dietary attitudes and behaviors, intake frequencies of food groups, health-related opinions and practices, and sociodemographic characteristics of housewives in Wonju-Gun rural area. Interviewers asked 413 housewives about obove informations and then recorded. The results were as followes : Using the factor analysis processing, 17 questions about dietary attitudes and behaviors were categorized into 5 groups such as fidelity of diet, the healthful dietary attitudes, the eating practices concerning about items and amount, eating speed and the extent of coincidence in food preference within a family. The role of the housewives was a major factor affecting the dietary attitudes and behaviors. Those who work as housewives and farmers concurrently had good dietary practices concerning about items and amount, but they were interested about health-directed dietary attitudes at a significantly lower level. Food frequencies of 9 groups, animal protein food, fruits and vegetables, milk and milk products, small fishes such as anchovy, soybean curd and beans, seaweeds, vegetable oil, frying food, soybean paste were significantly associated with subjects' age, role, and education and income level. Whether or not intake of soybean paste was considered. protein food intake was altered, and the difference between two situations increased much more as age was higher. We noticed that intake of soybean paste improved the status of protein nutrition. Our subjects ate calcium sources and dishes using vegetable oil insufficiently. Those who had much interests for good health, revealed to be an active practitioner in the aspects of healthful dietary attitudes, but fidelity of diet, eating practices concerning about items and amount showed significant association with balanced life style.

• Journal of Nutrition and Health
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• v.45 no.3
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• pp.229-239
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• 2012

The purpose of this study was to investigate and examine the relationship between dietary habits, food intake patterns, and depression in Korean women with polycystic ovary syndrome (PCOS). The Center for Epidemiologic Studies Depression Scale Korean Version was used to determine whether a participant was depressed or not. The dietary habits were assessed by the Min-Dietary Assessment (MDA) method, and food intake data were collected by the 24-hour recall method on two non-consecutive days, at least 7 days apart, and the average of the two days was used to estimate the usual dietary intake. The total MDA scores of the Depression Group was significantly lower than that of the No-Depression Group ($31.5{\pm}6.4$ vs $33.4{\pm}6.0$, p = 0.027). The intake of cereals/potatoes/sugar products, milk and milk products, plant protein, and calcium for the Depression Group were significantly lower compared to the No-Depression Group. The Depression Group had a significantly higher percentage of energy intakes from protein as well as the consumption of fish and shellfish compared to the No-Depression Group. There was a significant inverse relationship between milk and milk products consumption and the prevalence of depression [OR (95% CI) for the highest tertile compared to the lowest: 0.390 (0.177-0.857); p for trend = 0.016]. There were also significant positive relationships between the prevalence of depression and the consumption of the following: fish and shellfish [OR (95% CI) for the highest tertile compared to the lowest: 2.319 (1.128-4.770); p for trend = 0.009], animal protein (p for trend = 0.049), and the percentage of energy intakes from protein [OR (95% CI) for the highest tertile compared with the lowest: 2.546(1.156-5.609); p for trend = 0.025]. Further studies are needed in order to investigate whether the intake of protein and of animal protein is indeed associated with depression in PCOS patients in Korea and the possible mechanisms thereof. The results of our study can be applicable for the development of effective nutrition counseling and education programs regarding PCOS patients with depression as part of their successful treatment regimen.

• Korean Journal of Poultry Science
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• v.39 no.3
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• pp.207-213
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• 2012

This experiment was conducted to investigate the effects of various levels of dietary protein on laying performance and egg quality in laying quail. A total of six hundred forty 7-week-old laying type Japanese quail were divided into four groups with eight replicates per group (20 birds per replicate) and fed four diets differing in dietary protein levels (18, 20, 22 and 24%) with isocaloric corn-soybean meal-based diets for 8 weeks. The results showed no significant differences in feed intake and egg weight among the groups. With an increase in dietary protein levels, the egg production and daily egg mass were linearly increased (P<0.05). However, there were no significant differences in eggshell thickness and Haugh unit. The dietary protein did not affect the blood levels of GOT, GPT, BUN, albumin, and creatinine. The ammonia concentration of intestinal digesta was not affected by the dietary treatments. The contents of hepatic triacylglycerol in the groups fed diets containing 20% protein or more were significantly reduced as compared with that of 18% CP group (P<0.05). Overall, this study showed that relatively high levels of dietary CP are needed to sustain the higher egg production and daily egg mass and to avoid the hepatic triacylglycerol accumulation in Japanese quail.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.9
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• pp.1362-1370
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• 2015

This study was performed to investigate the effect of different levels of dietary crude protein (CP) on composition of odorous compounds and bacterial communities in pig manure. A total of 48 male pigs (average initial body weight 45 kg) fed diets containing three levels of dietary CP (20%, 17.5%, and 15%) and their slurry samples were collected from the pits under the floor every week for one month. Changes in composition of odorous compounds and bacterial communities were analyzed by gas chromatography and 454 FLX titanium pyrosequencing systems, respectively. Levels of phenols, indoles, short chain fatty acid and branched chain fatty acid were lowest (p<0.05) in CP 15% group among three CP levels. Relative abundance of Bacteroidetes phylum and bacterial genera including Leuconostoc, Bacillus, Atopostipes, Peptonphilus, Ruminococcaceae_uc, Bacteroides, and Pseudomonas was lower (p<0.05) in CP 15% than in CP 20% group. There was a positive correlation (p<0.05) between odorous compounds and bacterial genera: phenol, indole, iso-butyric acid, and iso-valeric acid with Atopostipes, p-cresol and skatole with Bacteroides, acetic acid and butyric acid with AM982595_g of Porphyromonadaceae family, and propionic acid with Tissierella. Taken together, administration of 15% CP showed less production of odorous compounds than 20% CP group and this result might be associated with the changes in bacterial communities especially whose roles in protein metabolism.

• Journal of Aquaculture
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• v.18 no.2
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• pp.92-97
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• 2005

This study examined the partial replacement of the fish meal with meat meal in practical diets for juvenile rock-fish. Five isonitrogenous (48% CP) diets were prepared to contain meat meal at 0% (control), 10%, 20%, 30% and 40% with substituting the mackerel meal in the control diet. Three replicate groups of fish (initial average weight, 4.1g) were hand-fed to visual satiety two times daily for 8 weeks. Survival (>93%) and daily feed intake were not significantly different (P>0.05) among treatments. The best weight gain, feed efficiency and protein efficiency ratio were obtained from fish fed the diets containing 0% and 10% meat meal, and were not significantly different (P>0.05) to those of fish 134 diet containing 20% meat meal. Condition factor, visceralsomatic index and hepatosomatic index were not influenced by dietary meat meal levels. The contents of crude protein and ash of whole body were not significantly affected (P>0.05) by dietary meat meal levels, whereas crude lipid content of fish fed the diets containing 30% and 40% was lower than that of fish fed the control diet. Proximate composition of liver was not influenced by dietary meat meal level (P>0.05). The data obtained in this study indicate that a diet containing $10{\sim}20%$ meat meal could be used for least-cost formulation in juvenile rockfish diet.

• Nutrition Research and Practice
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• v.17 no.5
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• pp.969-983
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• 2023

BACKGROUND/OBJECTIVES: We investigated the association of plant and animal protein intake with grip strength in Koreans aged ≥ 50 yrs. SUBJECTS/METHODS: The data was collected from 3,610 men and 4,691 women (≥ 50 yrs) from the 2016-2018 Korea National Health and Nutrition Examination Survey. We calculated the total energy intake, and the intake of animal and plant protein and collected dietary data using 1-day 24-h dietary recalls. Low grip strength (LGS) was defined as the lowest quintile (men: up to 26.8 kg, women: up to 15.7 kg). The association of protein intake with grip strength was examined using Pearson's correlation and multiple linear regression analysis. RESULTS: The results proved that participants with LGS had lower daily energy, protein and fat intake, and percent energy from protein than those with normal or high grip strength (P < 0.0001). Total energy intake, animal protein, and plant protein were positively associated with grip strength. A higher intake of total plant protein (P for trend = 0.004 for men, 0.05 for women) and legumes, nuts, and seeds (LNS) protein (P for trend = 0.01 for men, 0.02 for women) was significantly associated with a lower prevalence of LGS. However, non-LNS plant protein intake was not associated with LGS (P for trend = 0.10 for men, 0.15 for women). In women, a higher total animal protein intake was significantly associated with decreased LGS (P for trend = 0.03). CONCLUSIONS: Higher total plant protein and LNS protein intake are negatively associated with LGS.

• Animal Bioscience
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• v.35 no.2
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• pp.260-271
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• 2022

Objective: We aimed to investigate the effect of the differing amino acid (AA) release dynamics of two protein sources on the growth performance, nitrogen deposition, plasma biochemical parameters, and muscle synthesis and degradation of piglets when included in their diets at normal and low concentrations. Methods: Forty-eight piglets (Duroc×Landrace×Large White) with initial body weight of 7.45±0.58 kg were assigned to six groups and fed one of 6 diets. The 6 dietary treatments were arranged by 3×2 factorial with 3 protein sources and 2 dietary protein levels. They are NCAS (a normal protein content with casein), NBlend (a normal protein content with blend of casein and corn gluten meal), NCGM (a normal protein content with corn gluten meal), LCAS (a low protein content with casein), LBlend (a low protein content with blend of casein and corn gluten meal), LCGM (a low protein content with corn gluten meal). The release dynamics of AA in these diets were determined by in vitro digestion. The digestibility, utilization and biological value of nitrogen in piglets were determined by micro Kjeldahl method. Plasma insulin was measured by enzyme-linked immunosorbent assay kits. The protein expression of mediators of muscle synthesis and degradation was determined by western blotting. Results: Although the consumption of a low-protein diet supplemented with crystalline AA was associated with greater nitrogen digestion and utilization (p<0.05), the final body weight, growth performance, nitrogen deposition, and phosphorylation of ribosomal protein S6 kinase 1 and eIF4E binding protein 1 in the muscle of pigs in the low-protein diet-fed groups were lower than those of the normal-protein diet-fed groups (p<0.05) because of the absence of non-essential AA. Because of the more balanced release of AA, the casein (CAS) and Blend-fed groups showed superior growth performance, final body weight and nitrogen deposition, and lower expression of muscle ring finger 1 and muscle atrophy F-box than the CGM-fed groups (p<0.05). Conclusion: We conclude that the balanced release of AA from CAS containing diets and mixed diets could reduce muscle degradation, favor nitrogen retention, % intake and improve growth performance in pigs consuming either a normal- or low-protein diet.

• Nutrition Research and Practice
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• v.1 no.4
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• pp.247-253
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• 2007

Alpha-tocopherol transfer protein (${\alpha}$-TTP) is a liver cytosolic transport protein that faciliates ${\alpha}$-tocopherol (${\alpha}$-T) transfer into liver secreted plasma lipoproteins. Genetic defects in ${\alpha}$-TTP, like dietary vitamin E deficiency, are associated with infertility, muscular weakness and neurological disorders. Both human and ${\alpha}$-TTP deficient (${\alpha}-TTP^{-/-}$) mice exhibit severe plasma and tissue vitamin E deficiency that can be attenuated by sufficient dietary ${\alpha}$-T supplementations. In this review, we summarize the literature concerning studies utilizing the ${\alpha}-TTP^{-/-}$ mice. Levels of vitamin E in the ${\alpha}-TTP^{-/-}$ mice do not appear to be directly related to the amounts of dietary ${\alpha}$-T or to the levels of ${\alpha}$-TTP protein in tissues. The ${\alpha}-TTP^{-/-}$ mice appear to present a good model for investigating the specific role of ${\alpha}$-T in tissue vitamin E metabolism. Furthermore, ${\alpha}-TTP^{-/-}$ mice appear to be useful to elucidate functions of ${\alpha}$-TTP beyond its well recognized functions of transferring ${\alpha}$-T from liver to plasma lipoprotein fractions.