• Journal of Nutrition and Health
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• v.28 no.4
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• pp.298-308
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• 1995

To investigate the effect of estrogen and dietary protein level on Ca metabolism, female rats were undergone ovariectomy or sham-operation. Ovariectomized rate were divided into either estrogen-or vehicle-treated groups. Each treatment group was again divided into 40%-casein(H) or 10%-casein(L) diet groups. All experimental diets contained 0.2% Ca, 0.4% P and fed to rats for 8 weeks. Apparant Ca absorption and Ca balance were not affected by dietary protein level and ovariectomy, however they were increased by estrogen injection and this effect was even higher in low protein groups. Urinary Ca excretion were higher in high protein groups. GFR was not affected by dietary protein level, ovariectomy, or by estrogen injection. Urinary protein excretion was higher in high protein groups, which implies that the kidney funtion was deteriorated by high protein diet, and this may account partly for the higher urinary Ca in high protein groups. Ovariectomy or estrogen treatment had no effect on urinary protein excretion. Urinary hydroxyproline was higher in ovariectomized rats and increased in high protein grous. Elevated value of ovarictomized rats was lowered by estrogen injection, especially in low protein group. Alkaline phosphatase tended to increase in ovariectomized groups and lowered with estrogen treatment, but this difference was not statistically significant. Serum PTH was not affected by ovariectomy and dietary protein level. Therefore the increased hydroxproline excretion does not seem to be attributed to PTH. Dietary protein level, ovariectomy and estrogen treatment did not affect the weights and components of femur, scapular, and 4th vertebra. Ash/wt ratio of femur was, however, lower in ovariectomized rats and increased with estrogen treatment. Therefore, among the bones studied, femur seemed to be the most vulnerable. The results of this study shows that estrogen treatment may alleviate or reduce bone loss in postmenopausal women somewhat, especially for those people with low protein diet.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.11
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• pp.1629-1634
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• 2008

A trial was conducted to determine the effect of low crude protein (CP) diets with constant metabolizable energy to crude protein (ME:CP) ratio on growth, body composition and nutrient utilization of broiler chicks from 1 to 26 days of age. Four dietary treatments having four levels of CP and ME as 23, 22, 21 and 20% and 3,036, 2,904, 2,772 and 2,640 kcal/kg, respectively, were formulated and a ME:CP ratio of 132 was maintained in all the diets. Digestible lysine was maintained at 1.10 of the diet. A total of 1,760 day-old Hubbard broiler chicks were randomly divided into 16 experimental units and each diet was offered to four experimental units at random. Feed intake was increased (p<0.05) while weight gain and feed conversion ratio were adversely affected (p<0.05) when the diets with low CP and ME were fed to broilers. Total protein intake and total ME intake were linearly decreased (p<0.05) and protein efficiency ratio and energy efficiency ratio were lower (p<0.05) than in the chicks fed dietary regimen with 22% CP and 2,904 kcal/kg ME. The whole body analysis of the birds revealed that chicks fed the lowest dietary regimens retained less (p<0.05) nitrogen and more ether extract than chicks fed the control diet, however, body dry matter, total body ash and fat free body protein were not affected. Similarly, protein and energy utilization were also unaffected by the dietary treatments. In summary, chicks fed low CP diets with constant ME:CP ratio grew slower, used feed less efficiently and retained less protein and more body fat than chicks fed the control diet.

• Korean Journal of Poultry Science
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• v.44 no.2
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• pp.67-73
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• 2017

The purpose of our study was to determine the effects of varying levels of energy, protein, and amino acids on the performances of laying hens. A total of 240 Hy-Line Brown laying hens at 36 weeks of age were used in this 4-week feeding trial. The hens were randomly allocated to five treatment diets, with eight replications of six hens in each replicate cage. The treatment diets were as follows: A- basal diet + 18% crude protein, metabolizable energy 2,800 kcal, total (methionine + cysteine) 0.65%; B- basal diet + 17% crude protein, metabolizable energy 2,700 kcal, total (methionine + cysteine) 0.59%; C- basal diet + 16.5% crude protein, metabolizable energy 2,700 kcal, total (methionine + cysteine) 0.59%; D- basal diet + 16.5% crude protein, metabolizable energy 2,700 kcal, total (methionine + cysteine) 0.54%; and E- basal diet + 16% crude protein, metabolizable energy 2,680 kcal, total (methionine + cysteine) 0.54%. The study results revealed that the hen-day egg production of hens that were fed with low-energy diets (B, C, and D) was comparable with that of hens fed with high-energy diet A, whereas average daily feed intake in hens fed treatment diet D and E was significantly higher (P<0.05) than that in hens fed treatment diet A. Overall, the eggshell thickness was unaffected by any of the treatment diets. Egg weight was comparable among the treatment diets, except for treatment diet E. Haugh unit improved with decreasing levels of dietary energy, protein, and methionine + cysteine in the diet. We can summarize that laying hens fed with low dietary energy and low crude protein treatment diets B, C, and D had satisfactory performance compared with those fed with high-energy treatment diet A. This indicates that there is the potential to reduce feed costs by formulating diets with lower energy and low protein levels.

• Korean Journal of Community Nutrition
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• v.3 no.2
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• pp.218-227
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• 1998

This study was performed to investigate the effects of dietary protein and calcium levels on iron and zinc balance in eight healthy Korean young women. The 20-day metabolic study consisted of a 2-day adaptation period followed by three 6-day experimental periods. Three experimental diets were the low protein-low calcium(LProLCa ; protein 44g, Ca 422mg), the high protein-low calcium(HProLCa ; 'protein 85g, Ca 365mg) and the high protein-high calcium (HProHCa ; protein 84g, Ca 727mg). Apparent absorption and balance of iron and zinc were significantly higher when subjects were fed high protein-low calcium diet than low protein-low calcium diet. The elevation of dietary calcium significantly depressed the apparent absorption of iron and zinc. The levels of serum iron and zinc were likely to be increased with a high protein diet, but the differences were not significant. There was a strong correlation(r=O.99) between the iron intake and serum iron concentration. Serum zinc concentration was not correlated with hair zinc. Study results revealed that the levels of dietary protein and calcium influence iron and zinc balance in Koreans. This study suggests that dietary recommendations for trace minerals, such as iron and zinc, should be carefully examined. In addition, there is a need to evaluate the bioavailability of milk or beverage products enriched with calcium and iron.

• Animal Bioscience
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• v.34 no.10
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• pp.1600-1606
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• 2021

Objective: This study was conducted to enhance our understanding of nitrogen (N) metabolism and mammary amino acid (AA) utilization in lactating cows with divergent phenotypes of residual feed intake (RFI). Methods: Fifty-three multiparous mid-lactation Holstein dairy cows were selected for RFI measurements over a 50-d experimental period. The 26 cows with the most extreme RFI values were classified into the high RFI (n = 13) and low RFI (n = 13) groups, respectively, for analysis of N metabolism and AA utilization. Results: Compared with the high RFI cows, the low RFI animals had lower dry matter intake (p<0.01) with no difference observed in milk yield between the two groups (p>0.10). However, higher ratios of milk yield to dry matter intake (p<0.01) were found in the low RFI cows than in the high RFI cows. The low RFI cows had significant greater ratios of milk protein to metabolizable protein (p = 0.02) and milk protein to crude protein intake than the high RFI cows (p = 0.01). The arterial concentration and mammary uptake of essential AA (p<0.10), branched-chain AA (p<0.10), and total AA (p<0.10) tended to be lower in the low RFI cows. Additionally, the low RFI cows tended to have a lower ratio of AA uptake to milk output for essential AA (p = 0.08), branched-chain AA (p = 0.07) and total AA (p = 0.09) than the high RFI cows. Conclusion: In summary, both utilization of metabolizable protein for milk protein and mammary AA utilization are more efficient in cows with lower RFI than in the high RFI cows. Our results provide new insight into the protein metabolic processes (related to N and AA) involved in feed efficiency.

• Animal Bioscience
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• v.36 no.6
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• pp.920-928
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• 2023

Objective: Angora rabbits fed a low-protein diet exhibit decreased hair production performance. This study was set out to evaluate the effects of methionine on hair properties and nitrogen metabolism in Angora rabbits fed a low-protein diet and to investigate the gene expression related to hair follicle development to determine the possible molecular mechanism of methionine effects on hair follicle development. Methods: An experiment was conducted to investigate the effects of DL-methionine addition on a low-protein diet on hair development in Angora rabbits. Angora rabbits were divided into 5 groups: fed a normal diet (control), fed a low-protein diet (LP), or fed an LP supplemented with 0.2%, 0.4%, or 0.6% DL-methionine (Met). Results: The results showed that rabbits in the LP group had lower wool yield than the control rabbits, but the addition of 0.4% to 0.6% Met to LP attenuated these effects (p<0.05). Dietary addition of 0.4% to 0.6% Met to LP increased the apparent nitrogen digestibility, nitrogen utilization rate, and feed efficiency (p<0.05). Feeding LP decreased the insulin-like growth factor 1 (IGF1), keratin-associated protein (KAP) 3.1, and KAP 6.1 mRNA levels compared with the control, but the addition of 0.4% Met in LP attenuated these effects (p<0.05). Relative to the LP or control group, dietary addition of 0.4% Met increased versican mRNA levels. Conclusion: In conclusion, the addition of Met to LP could improves wool production performance and feed efficiency and reduce nitrogen emissions in Angora rabbits. Met can promote hair follicle development, which may be associated with IGF1, KAP, and the versican signaling.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.279-283
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• 1992

This study was undertaken to investigate the effects of added phytate and pH on the solubility and in vitro digestibility of low-phytate rapeseed protein isolate. Phytate content of low-phytate rapeseed protein isolate was 1.5%, as a result of 66% removal from defatted rapeseed flour and the protein: phytate ratio was 58:1. Solubility of rapeseed protein isolate at pH 2.0 and pH 11.5 was much higher than near the isoelectric point, pH 5.0. It's solubility was lowered by adding an increased amount of phytate especially at pH 2.0. The inhibitory effect of phytate toward pepsin digestibility of rapeseed protein isolate decreased by the increasing amount of phytate added. It is suggested that the production of low-phytate rapeseed protein isolate is necessary to improve the functionality and nutritional value in order to utilize it as food material.

• KSBB Journal
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• v.24 no.1
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• pp.96-100
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• 2009

One of the major drawbacks associated with the high-level expression of the recombinant proteins in Escherichia coli is the formation of insoluble inclusion bodies in the cytoplasm. Production of recombinant protein at reduced temperature has proven effective in improving the solubility of a number of structurally and functionally unrelated proteins, but a major limitation of using low temperatures for recombinant protein production in E. coli is the reduced rate of synthesis of the heterologous protein caused by the significant reduction of cell growth rate. Here we investigated the effect of co-expression of CspA, a cold-shock protein known to be RNA chaperone at low temperature, on the productivity of recombinant protein at various temperatures by using green fluorescence protein (GFP) as a model recombinant protein. We could observe that the co-expression of CspA enhanced the productivity of GFP at $15^{\circ}C$ by accelerating the growth of E. coli at the temperature. On the other hand, the CspA coexpression didn't affect the cell growth rate as well as the specific GFP production rate at other tested temperatures, $20^{\circ}C$, $25^{\circ}C$, and $37^{\circ}C$.

• Journal of Nutrition and Health
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• v.19 no.1
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• pp.66-73
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• 1986

This study was undertaken to investigate the effects of age and of the dietary protein sources & levels on urinary calcium excretion and bone metabolism in the rats. Two experiments were conducted . In experiment U, 6& 20 weeks old rats were fed 8 & 36%, casein & ffish protein diet for 5 weeks . In experiment II, 16& 52 weeks old rats were fed 40 % protein diets, protein sources were casein, fish and gluten. High-protein diet group excreted more caldium in urine than low-protein group. Urinary calcium excretion was affected by the sources of protein ; gluten group excreted more Ca, followed by fish & casein group. Total bone Ca & Ca proportion in ash were higher in 20 weeks old rats than 6 weeks old rats, but 16 & 52 weeks old rats showed no differences. bone composition showed that water proportion was high and ash proportion was low in 6 weeks old rats than in 20 weeks old rats. However, these tendencies were not observed between 16 weeks and 52 weeks old rats. And bone composition was affected by protein sources ; higher ash proportions were noted in one order of casein, fish, and gluten water proportion were lower in one same order.

• Journal of Nutrition and Health
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• v.25 no.7
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• pp.569-577
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• 1992

To study the effects of the age and the dietary protein content on Ca metabolism male rats of 1 month 6 month 12 month of age were fed experimental diets containing 5%, 15% or 50% casein for 4 weeks. Food and ca intake were higher in old rats and in high protein groups. The weight ash and Ca contents of femur and tibia were higher in old rats. The higher dietary protein level resulted in higher skeletal weigh ash and Ca contents. But high protein diet(50% casein) lead to reduced bone mineral density(ash/dry bone weight) and Ca density(Ca/dry bone weight) in 1 month old rats. Low protein diet(5% casein) on the other hand reduced the bone growth even though the bone density was higher in this group. The ill effect of low protein diet was not evident in 12 month old rats. Glomerular filteration rate(GFR) and urinary Ca excretionincreased with age and with dietary protein level especially in 12 month old rats. Serum immunoreactive parathyroid hormone(iPTH) level tended to be higher in aged rats but was not affected by dietary protein level except 1 month old rats where 50% protein group showed significantly higher value. This study showed that the dietary protein level seemed to have different effect on Ca metabo-lism in rats of different age., The low bone density in the high protein group of growing rats may be due to the higher iPTH level and increased urinary Ca. The dietary protein level however had no effects on the bone composition in aged rats even though the higher urinary Ca excretion. In conclusion this study suggests that high protein intake from young may lead to less peak bone mass and to increase the bone loss in later years, which would increase the risk for osteporosis.