• Journal of Nutrition and Health
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• v.21 no.1
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• pp.47-60
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• 1988

This study was performed to investigate the effect of dietary levels on protein metabolism in eight healthy Korean adult females. The 20-day metabolic study consisted of 2 day adaptation period and three 6-day experimental. Three experimental diets were low protein (LP : protein 44g), high protein(HP : protein 85g) and high animal protein (HAP : protein-84g). The apparent absorption and balance on nitrogen were significantly higher in high protein than in low protein diet. Nitrogen, absorption rate was about 75% for low protein and about 85% for high protein intake. The mean values of nitrogen balance were -1.28% for low protein and 0.78% for high protein diet. All the subjects were in negative nitrogen balance at the low protein intake while they were in positive nitrogen balance at the high protein intake. The mean daily urinary nitrogen excretion increased with increased level of protein intake. Urea nitrogen was the largest part of the urinary nitrogen. The ratio of urea nitrogen to total urinary nitrogen increased significantly for 79 to 85% as protein intake was doubled.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.s01
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• pp.39-47
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• 1988

Soybean grain is most widely used and soybean crop produces most high protein per area among crops. To meet rapid increase of human population and supply protein in safety. soybean has considered more and more important crop. And it has been emphasizing that high quality and high protein soybean breeding must be made efforts in future. Many papers related to soybean breeding for high quality and protein and soybean protein composition have suggested the problems to do in future. Soybean germplasm collection. classification and conservation should be continuously performed, and it is emphasized that wild type of soybeans (G. soja) be considered to use in breeding for high protein varieties. Selections would be better emphasized in first yield and therefore high yield of protein per area. Selection for high protein would be secondary criterion. High protein lines with high yielding potential could be selection from certain populations, and breeders should consider this phenomenon in procedure of selection. Heritability of protein percent is relatively high and genetic gain of increment of protein percent is large. Soybean protein which is comprised 70 to 90% of globulin is constituted mostly 11S and 7S proteins. Sulfur-containing amino acids, methionine and cysteine, are identified to contain more in 11S protein than 7S protein. High 11S germplasm should be desirable to use in crossing plan, and selection of high ratio of 11S/7S lines be better in development of high quality varieties.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.6
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• pp.894-898
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• 1994

To evaluate an effect of dietary protein on the liver damage, the bromobenzene was intraperitoneally injected to the rats fed a low or high protein diet and then the liver weight per body weight and serum levels of alanine aminotransferase (ALT) activities were determined to demonstrate the differences in liver damage between the groups fed low or high protein diet. Hepatic aniline hydroxylase (AH), glutthione (GSH) content and glutathione s-transferase(GST) activity were also determined to clarify causes of liver damage between the two groups. Increases of liver weight per body weight and serum ALT activities were higher in brombenzene treated rats fed low protein diet than those fed high protein diet. The increasing rate of hepatic AH activity was higher in bromobenzne-treated rats fed low protein diet than that in those fed high protein diet. Furthermore , hepatic glutathione contents and GST activities in bromobenzene-treated rats were higher in rats fed high protein diet than those fed low protein diet. In case of control group, the heaptic glutathione content and GST activity were also higher in rats fed high protein diet than those fed low protein diet.

• Journal of the Korean Home Economics Association
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• v.29 no.3
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• pp.47-59
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• 1991

This study wa performed to investigate the effects of dietary protein and fiber on the lead and protein metabolism in lead poisoning rats. Seventy male rats of Sprague-Dawley strain weighing 172$\pm$2g were blocked into 14 gropus according to body weight. Protein(casein) was given at levels of 15 or 40%, and fibers(pectin, cellulose and CMC) were given at levels of 0, 4 or 10%. The results are summarized as follows: 1. Food intake, weight gain and food efficiency ratio(FER) in groups fed high protein diets were higher than those in low protein groups. Liver weight in groups fed no dietary fiber was higher than that of animals fed fiber. Kidney and femur weights were greater in high protein groups. Tibia and femur lengths, and tibia weight were not significantly different among groups. 2. Hemoglobin content and hematocrit values showed no significant differance with dietary factors. 3. Total protein contents of serum and liver showed no significant difference, but tended to increase with increasing dietary protein level. Both daily urinary and fecal nitrogen excretions in high protein groups were higher than those in low protein groups. Especially daily fecal nitrogen excretions in high dietary fiber groups were significantly high. Body nitrogen absorption rate was the highest in animals fed no fiber. 4. Pb levels in blood, liver, kidney and bone tended to decrease with high dietary protein and fiber levels. Especially Pb level of kidney was high in all groups. Daily urinary Pb excretion showed no significant difference with dietary factors, but fecal Pb excretion increased significantly in high protein and fiber groups.

• Journal of Nutrition and Health
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• v.27 no.5
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• pp.451-459
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• 1994

This study was performed to investigate the effect of sources of protein on iron bioavailability in 10 healthy young Korean women. The 18-day metabolic study consisted of a 6-day adaptation period, 6-day moderate protein(60g protein/day, 18mg Fe/day) and 6-day high protein period(90g protein/day, 18mg Fe/day). During the moderate and high protein period, 5 subjects were fed the high plant protein meals(80% plant protein). Fecal excretion of dietary iron was significantly higher(p<0.05) in high protein high plant diet group(HPP, 9.48$\pm$1.61mg/day) than in high protein high animal diet group (HPA, 14.40$\pm$0.89mg/day). Apparent absorption and bioavailability of iron was also significantly higher(p<0.10) in HPA(40.7$\pm$5.3%, 6.46$\pm$1.61mg/day) than in HPP(14.4$\pm$5.3%, 2.39$\pm$0.89mg/day). But there was no significant difference between the high animal protein group and high plant protein group in moderate protein period. Serum iron concentration and transferrin saturation increased as animal protein intake increased, from 106.0$\pm$5.1ug/이 and 30.6$\pm$1.5% for MPA to 129.1$\pm$6.7ug/이 and 37.1$\pm$1.3% for HPA. Statistically positive correlations were shown not only between the level of dietary heme iron and apparent absorption(r=0.95, p<0.05), but also between serum iron concentration and apparent absorption(r=0.64, p<0.05). Negative iron balance was shown in two subjects fed the moderate protein meals. These results suggest that recommanded dietary allowances of iron may be under the need to maintain the positive balance, and iron bioavaliability increase by only high level of animal protein intake.

• Journal of Nutrition and Health
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• v.22 no.6
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• pp.497-506
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• 1989

To investigate the effect of levels of dietary protein and age on bone metabolism 40% and 5% casein were fed to the rats of 2 & 13 months of age for 12 weeks. High protein groups showed higher bone weight and Ca content than low protein groups and urinary Ca loss was increased in high protein groups but the difference disappeared gradually. A significant increase in urinary hydroxyproline excretion was noted in high protein groups of both age. Another short term study was undertaken to study if the above effect was related with renal function or PTH. Extremely high and low protein diets(60%, 6%) were fed to the rats of different ages(6wks, 6mos.) for 2 weeks, Urinary Ca excretion was significantly increased in high protein groups of young and aged rats and GFR was increased as well. There was no difference in serum iPTH levels between low and high protein groups, but it was elevated in aged rats. Alkaline phosphatase activity was higher in young rats, reflecting faster bone formation. The observed hypercalciuria in high protein groups, especially in aged rats, seems to be related to higher GFR, and PTH dose not appear to be a major mediator.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.1
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• pp.15-18
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• 1993

To evaluate an effect of dietary protein on the intoxication of methanethiol in rats, the methanethiol was intraperitoneally injected to the rats fed a low or high protein diet and then the liver weight per body weight and seurm levels of alanine aminotransferase (ALT) activities were determined to investigate the differences in liver damage between the animal groups fed low protein diet and that fed high protein diet. On the other hand, the hepatic glutathione content and its conjugating enzyme, glutathione S-transferase (GST) activity were determined to clarify the cause of difference in liver function between the two groups. The increasing rate of liver weigh/body wt., serum levels of ALT to its control group were higher in methanethiol-treated rats fed low protein diet than those fed high protein diet. The hepatic content of glutathione and GST activity were higher in rats fed high protein diet than those fed low protein diet and the decreasing rate of hepatic glu-tathione content to its control group was higher in rats fed low protein diet than those fed high protein diet. Furthermore, the hepatic GST activity in methanethiol-treated rats was higher in rats fed high protein diet than those fed low protein diet. In case of control group, the GST activity was also higher in rats fed high protein diet than those fed low protein diet.

• Asian-Australasian Journal of Animal Sciences
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• v.7 no.2
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• pp.207-212
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• 1994

Effects of dietary cellulose and protein levels on nutrient utilization in chickens were investigated. Four experimental diets containing 5% (low cellulose) or 20% (high cellulose) cellulose in combination with 10% (low protein) or 20% (high protein) protein of 70 g/day were alternatively forced-fed to eight colostomized White Leghorn cockerels once a day to make $4{\times}4$ Latin-square design. The digestibilities of DM and energy decreased with the increase in cellulose level, but not affected by dietary protein level. Ether extract digestibility was higher in the high cellulose diets than in the low cellulose protein level. Ether extract digestibility was higher in the high cellulose diets than in the low cellulose diets. The digestibility of nitrogen free extract had the same trend with the digestibility of DM and energy. The digestibility of acid detergent fiber was not so much different among the diets, but the NDF digestibility was lower in the high cellulose diets than in the low cellulose diets, due to the low hemicellulose digestibility. The true digestibility of protein was influenced by both of the dietary protein and cellulose levels, and their interaction was found. The dietary protein level affected the biological value of protein but the dietary cellulose level did not, and consequently the biological value of protein in the low protein diets was lower than in the high protein diets.

• Korean Journal of Poultry Science
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• v.34 no.3
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• pp.217-222
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• 2007

This study was conducted to investigate the effects of mud flat bacteria origin protease supplementation by crude protein level on growth performance, nutrient digestibility, total protein and BUN (blood urea nitrogen) concentration in broilers. A total of four hundred eighty broilers were randomly allocated into four treatments with six replications for five weeks. Dietary treatments included 1) high crude protein diet, 2) high crude protein diet + 0.1% protease, 3) low crude protein diet and 4) low crude protein diet + 0.1% protease. During the entire experimental period, weight gain and feed/gain were improved in treatments of high crude protein diets and low crude protein diet added protease compared with treatment of low crude protein diet without protease (P<0.05). Similarly, DM digestibility was also improved in treatments of high crude protein diets and low crude protein diet added protease compared with treatment of low crude protein diet without protease (P<0.05). N digestibility was improved in treatment of high crude protein diet added protease compared with low crude protein diet without protease (P<0.05). Total protein concentration in blood was increased in treatment of high crude protein diet without protease compared with other treatments (P<0.05). In conclusion, mud flat origin protease was effective in improving weight gain, feed/gain and nutrient digestibility, and influenced blood total protein in broilers.

• Journal of Nutrition and Health
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• v.29 no.6
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• pp.578-589
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• 1996

This study was performed to invstigate the effect of dietary protein level and source on cadmium intoxicification in rats. Forty-eight male rats of Sprague-Dawley strain weighing 171$\pm$3g were blocked into 8 groups of 6 animals according to body weigth, and were raised for 30days. Eight experimental diets different with cadmium(0ppm, 400ppm)and protein(15%, 40%) levels and protein source[casien, I.S.P.(isolated soy protein)] were given to animals for 30days. Food intake, weight gain, food efficiency ratio, liver weight, kidney weight and femur weight were lower in cadmium added group, and higher in high protein groups(40% protein) than medium protein groups(15% protein). But, dietary protein source had no influence on them. Cadmium concerntration of liver was higher in rats fed casein than I.S.P. groups, and cadmium concentration in intestine was higher in high protein groups. In femur both high protein and I.S.P.diets increased cadmium concentrations. MT concdentrations in liver, kidney and intestine were higher in cadmium added group, and kidney intestine MT concentration were higher in high protein group. Absorption and retention rates of cadmium were lower in rat fed I.S.P. than animal fed casein among medium protein groups and cadmium concentration in blood and liver of I.S.P groups were lower than casein groups. But absorption and retention rates of cadmium were similar in high casein and I.S.P. groups. Renal damage by cadmium administration was not seen in all groups. Absorption rates of zinc and copper competing with cadmium in absorption process were lower in high protein groups than medium protein groups and lower in rats fed I.S.P. than casein. In conclusion, weight gain, F.E.R, and MT concentraion of high protein groups were higher than those of medium protein groups and absorption and retention rates of cadmium were lower in high protein groups. From these results, it was shown that cadmium toxicity was alleviated by high dietary protein. Meanwhile, the effect of dietary source on the cadmium toxicity was different with protein level. In medium protein groups absorption and retention rates of cadmium were much lower in rats fed I.S.P. than casein. In high protein groups, cadmium toxicity was not influenced by protein source and absorption and retention rates of cadmium were not different between casein and I.S.P. groups.