• Journal of Nutrition and Health
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• v.29 no.10
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• pp.1059-1071
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• 1996

This study was performed to investigate the effect of dietary protein level on renal senescence. Male rats of 337.8$\pm$5.7g body weight were underlateral nephrectomy or shamoperation. The rats were divided into high protein(40% casein), normal protein(15% casein) and low protein(8% casein)diets and fed experimental diets ad libitum for 24 weeks. The results are summarized as follows. There was a hypertophy of the remnant kidney of uninephrectomized rats of 40% or 15% protein group, coming up to the comparable weights of both kidneys of sham-operated rats. However, the hypertrophic effect was not seen in uninephrectomized rats of 8% protein group. Serum albumin was lower in uninephrectomized rats. With increasing dietary protein level blood urea nitrogen was increased, whereas, urinary urea nitrogen excretion was decreased. Urinary solute excretion was higher in uninephrectomized group than in sham-operated group. However, effect of dietary protein level on urinary solute excretion varied dpending on th solutes tested. GFR and urinary protein excretion, throughout experiment, increased with feeding period and with dietary protein level. Proteinuria was most severe in uninephrectomized rats fed 40% casein diet. Maximum urine concentration ability measured after dehydration was not different among the experimental groups. Light microscopic examination showed focal segmental glomerulosclerosis and mild increas of glomerular mesangial matrix in uninephrectomized rats fed 40% and 15% protein diet, however, which was not observed in uninephrectomized rats fed 8% protein diet and in sham-operated rats fed 40% diet. Immunofluorescence studies revealed segmental deposits of albumin in the mesangium and capillary loops in high protein and uninephrectomized groups. Minimal granular deposition of IgG was noted in the mesangium of all experimental groups. In conclusion, high protein intake accelerated deterioration of renal function and it was correlated with morphological change. Low protein intake was effective in preventing these changes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.3
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• pp.350-357
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• 2021

This study aimed to evaluate how fish meal (FM) replacement in diets with a mixture of animal and plant protein sources affect growth performance, feed utilization, hematological parameters and innate immunity of red seabream Pagrus major. A control FM diet was formulated to contain 65% FM (Con). Two other diets were prepared replacing FM in the control diet with a mixture of protein sources (wheat gluten, soy-protein concentrate, tankage meal, and poultry by-product meal) by 30 and 40% (FM30 and FM40, respectively). Total 300 red seabream (body weight, 77.6±0.3g) were distributed to 12 tanks (300 L) in 4 replicates per diet. The fish were fed the diets to apparent satiation for 19 weeks. After the feeding trial, no significant differences could be observed in growth performance, feed utilization, hematological parameters, innate immunity, and survivals among all the dietary treatments. This long-term feeding trial at low water temperature (13.8-17.5℃) indicates that a proper mixture ratio of wheat gluten, soy protein concentrate, tankage meal, and poultry by-product meal can replace FM up to 40% in red seabream diets.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.1
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• pp.55-61
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• 2014

Forty-eight Pelibuey${\times}$Katahdin male intact lambs ($23.87{\pm}2.84$ kg) were used in an 84-d feeding trial, with six pens per treatment in a $2{\times}2$ factorial design arrangement. The aim of the study was to evaluate the interaction of two dietary energy levels (3.05 and 2.83 Mcal/kg ME) and two dietary protein levels (17.5% and 14.5%) on growth performance, dietary energetics and carcass traits. The dietary treatments used were: i) High protein-high energy (HP-HE); ii) High protein-low energy (HP-LE); iii) Low protein-high energy (LP-HE), and iv) Low protein-low energy (LP-LE). With a high-energy level, dry matter intake (DMI) values were 6.1% lower in the low-protein diets, while with low-energy, the DMI values did not differ between the dietary protein levels. Energy levels did not influence the final weight and average daily gain (ADG), but resulted in lower DMI values and higher gain efficiencies. No effects of protein level were detected on growth performance. The observed dietary net energy (NE) ratio and observed DMI were closer than expected in all treatments and were not affected by the different treatments. There was an interaction (p<0.03) between energy and protein level for kidney-pelvic and heart fat (KPH), KPH was higher in lambs fed high energy and high protein diet but not in high energy and low protein diet. The KPH was increased (20.2%, p = 0.01) in high-energy diets, while fat thickness was increased (21.7%, p = 0.02) in high-protein diets. Therefore, it is concluded that dietary energy levels play a more important role in feed efficiency than protein levels in finishing lambs with a high-energy diet (>2.80 Mcal/kg ME). Providing a level of protein above 14.5% does not improves growth-performance, dietary energetics or carcass dressing percentage.

• Journal of the Korean Chemical Society
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• v.15 no.2
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• pp.69-84
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• 1971

An analysis of the free amino acid contained in the plasma and erythrocytes of the six groups of Wistar Strain male adult rats (body weight 200-300g) having fasted for sixteen hours was made by means of the HITACHI Amino Acid Autoanalyzer and the result of which was corrected with RC-24B TOMY Micro Hematocrit Centrifuge. There was a depression of the plasma and erythrocytes free amino acid level on the no-protein diet with ad libitum feeding. But on the 20% casein diet there was an elevation in the levels of free amino acid and consequently alanine, glysine, lysine, serine and arginine level in the erythrocytes and threonine, glutamic acid and taurine level in the plasma increased on the high protein diet. There was more plasma and erythrocytes free amino acid level on the 5% casein- 30% fat diet than on the 5% casein-no fat diet with pair-feeding. In comparison, on the low calorie diet more free amino acids were found in plasma than in erythrocytes, but on the higher calorie diet more free amino acids were found in the erythrocytes than in the plasma. On the 20% casein-30% fat diet with pair-feeding the erythrocytes free amino acids level increased but in plasma free amino acids level decreased. Such as an opposite result was given in plasma and erythrocytes free amino acids level. In the pair-fed four groups, erythrocytes per plasma generally increased in the rate of less than 10.0 as the calorie increased. The essential amino acid per non essential amino acid generally increased in the ratio as protein level and calorie increased, and that ratio range was from 0.2 to 0.7. And essential amino acid per non essential amino acid of plasma was higher than that of erythrocytes.

• Journal of Nutrition and Health
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• v.26 no.3
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• pp.231-247
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• 1993

This study was designed to confirm the effect of dietary protein level and oral administration of tryptophan on brain serotonin metabolism. Two animal experiments were conducted. The objectives and results of research were as follows : In the first experiment, it was investigated whether administration of reserpine to Sprague-Dawley rats fed 6% or 20% casein diet induced decrease in serum tryptophan and large neutral amino acid(LNAA) concentrations, tryptophan/LNAA concentration ratio, brain tryptophan, serotonin and 5-hydroxyindoleacetic acid(5-HIAA) contents. Brain serotonin content of 6% casein diet group was lower than those of 20% casein diet group. Both 6% and 20% casein diet groups administered with reserpine to induce the analogous depression, showed the notable decrease in brain serotonin content when they were compared with 20% casein diet group not administered with reserpine. Serum tryptophan/LNAA ration and brain 5-HIAA content showed a tendency similar to the change of serotonin content, but the mean difference among all groups was not significant. From these results, it could be said that when the dietary protein level was low, brain serotonin content was decrease. The second experimnt was to see the change in serum tryptophan concentration and tryptophan/LNAA ratio and brain tryptophan, serotonin and 5-HIAA content when tryptophan was administered orally to the animals treated with reserpine. Serum tryptophan concentration tended to increase in both reserpine-treated 6% and 20% casein diet groups administered with tryptophan, especially in the 6% casein diet group. Serum tryptophan/LNAA concentration ratio tended to incrase in reserpine-tteated 6% casein diet group, while decrease in reserpine-treated 20% casein diet group. Brain tryptophan content was increased in both reserpine-treated 6% and 20% casein diet groups. However, brain serotonin content of reserpine-treated 6% casein diet group showed a tendency to decrease, while that of reserpine-treated 20% casein group increase. Consequently, the effect of tryptophan administration on increase of brain tryptophan and serotonin content in animals treated with reserpine was far more excellent in 20% casein diet groups. It was concluded that dietary protein intake and tryptophan administration increase brain serotonin level. Accordingly, it was possible to confirm that brain function, particularly in aspect of behavior related to the serotonin, was changed with manipulation of dietary composition.

• Animal Bioscience
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• v.35 no.10
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• pp.1535-1544
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• 2022

Objective: The objective of this study was to investigate the effects of decreasing dietary crude protein content on rumen fermentation, mictobiota, and metabolites in goats. Methods: In an 84-day feeding trial, a total of twelve male Anhui white goat kids with initial body weight 15.9±1.13 kg were selected and randomly classified into two groups, feeding a normal crude protein diet (14.8% CP, NCP) or a low crude protein diet (12.0% CP, LCP). At the end of the experimental trial (on day 84), six animals were randomly selected from each group and were slaughtered to collect rumen fluid samples for the analysis of rumen fermentation parameters, microbiome, and metabolome. Results: The concentrations of ammonia-nitrogen, total volatile fatty acid, acetate, and propionate were decreased (p<0.05) in the LCP group in comparison with those in the NCP group. The abundances of genera Prevotella, Campylobacter, Synergistetes, and TG5, which were associated with nitrogen metabolism, were lower (p<0.05) in the LCP group compared with those in the NCP group. The levels of 78 metabolites (74 decreased, 4 increased) in the rumen fluid were altered (p<0.05) by the treatment. Most of the ruminal metabolites that showed decreased levels in the LCP group were substrates for microbial protein synthesis. Metabolic pathway analysis showed that vitamin B6 metabolism was significantly different (p<0.05) in rumen fluid between the two treatments. Conclusion: Decreased dietary protein level inhibited rumen fermentation through microbiome and metabolome shifts in goat kids. These results enhance our understanding of ruminal bacteria and metabolites of goat fed a low protein diet.

• Journal of Korea Association of Health Promotion
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• v.3 no.1
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• pp.24-34
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• 2005

Background: A reasonable weight reduction is to reduce fat-body mass while preserving free-fat mass. Recently, many people in Korea have been trying reckless diet therapy for weight reduction by low calory and protein diets, which gave rise to many side effects consequently. For reasonable weight reduction, this study was undertaken to investigate the influential diet factors that change body composition during short-term low calory diet. Methods: 26 healthy obese women aged 23-27 years whose BMI was greater than 24volunteered for the 6 week diet therapy from January to April in 2003. All subjects were instructed to eat approximately 1200kca1/day and write dietary diary. In the beginning of the study, the 3rd week and the 6th week, subjects' body weight and fat body weight were measured by BlA. In the 6th week, the analysis of dietary diary was conducted. Results : There was significant positive correlation between protein intake per ideal bodyweight in the first 3 weeks and free fat mass increase in the later 3 weeks (P<0.05). At the same time, fat intake in the first 3 weeks had positive correlation with free fat mass in the second 3 weeks, too(P<0.05). But, we could not find any significant values that had effect on free fat mass increase in multiple regression analysis. Conclusion: The protein intake in the first 3 weeks helps preserve fat free mass in the later 3 weeks, and has positive effects.

• The Korean Journal of Community Living Science
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• v.26 no.4
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• pp.661-673
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• 2015

This study examines the effects of a low-calorie raw juice diet on the level of serum ferritin in adults and analyzes nutrient intake from the diet. There were significant differences between juices; the highest calorie was provided by pear juice, highest crude protein, vitamin A, and vitamin B2 levels were from green Juice 1; and highest vitamin C and vitamin B1 levels were from fruit juices. The ratio of estimated energy requirements (EER) for the participants was 56.2% from the raw juice diet. The percentages of recommended intake (RI) from the raw juice diet of protein (57.9%), dietary fiber (19.1%), niacin (6.2%), calcium (0.1%), and magnesium (0.2%) were lower than 75%. However, those of RI of vitamin A, vitamin B1, vitamin B2, vitamin B6, and vitamin C were 1796.5%, 7481.7%, 1915.5%, 30858.7%, and 7500%, respectively, exceeding the tolerable upper intake level (UL) for vitamin A, vitamin B6, and vitamin C. There were significant decreases in weight, the body mass index (BMI), body fat mass, and skeletal muscle mass in males and females. After the diet program, serum iron and SOD (superoxide dismutase) showed significant decreases, whereas RBC, hemoglobin, hematocrit, and serum ferritin showed significant increases. There were negative correlations between serum ferritin and weight and between serum ferritin and skeletal muscle mass for all participants. There were negative correlations between serum ferritin and skeletal muscle mass for males and between serum ferritin and body fat mass for females. These results suggest that a raw juice diet can supplement a regular diet to prevent excess or deficient nutrient intake.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.2
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• pp.149-158
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• 2019

This study investigated the effects of replacing fish meal (FM) with a mixture of four protein sources (wheat gluten, soy protein concentrate, tankage meal, and poultry byproduct meal) in an extruded pellet (EP) diet for olive flounder Paralichthys olivaceus. Five experimental diets were formulated with alternative proteins replacing 0%, 20%, 30%, 40%, and 50% of FM. Taurine and betaine were added as attractants in the diets. Triplicate groups of fish (initial body weight: $196{\pm}2g$) were fed the diets to apparent satiation. Over the course of a 6-month feeding trial, there were no significant differences between the groups in growth performance, feed utilization, survival, or villus height. The dry matter and protein digestibility of FM50 diet were significantly lower than those of the control diet at water temperatures below $18.5^{\circ}C$ in months 4 and 6. This is a highly significant first report on FM replacement in an EP diet given to olive flounder over a 6-month-long feeding period. It shows that the proper mixture of protein sources can replace up to 50% of FM in olive flounder EP diets with taurine and betaine supplementation. It also shows that 40% of FM could be safely replaced in EP diets during periods of low water temperature.

• Journal of Nutrition and Health
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• v.11 no.3
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• pp.31-36
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• 1978

This experiment was designed to observe some influence on the serum components of growing rats maintained with basal diet supplemented with sausage. Forty male Albino rats were used as the experimental animals and the subjects were divided into four diet groups (control group; feeding of basal diet containing 10.8% and 10.4% of protein and lipid respectively, A group; feeding of sausage containing 12.5% and 27.6% of protein and lipid respectively supplemented with basal diet every day, B group; feeding of sausage supplemented with basal diet once a three-day and C group; feeding of sausage supplemented with basal diet once a five-day) and each group was fed on the corresponding diet for forty-days. The contents of protein, lipid and cholesterol in their serum were determined. The result obtained are summarized as follows: 1) The final body weight and liver weight of the A group were increased more than other groups. 2) The protein contents in the serum of the B group was increased more than other groups. 3) The total lipid contents in the serum of the A group and B group were decreased compared with control group. 4) The total cholesterol, ester form cholesterol and free form cholesterol in the serum of the A group were decreased, but the total cholesterol and ester form cholesterol in that of the C group were increased compared with control group.