• Fisheries and Aquatic Sciences
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• v.20 no.5
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• pp.7.1-7.6
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• 2017

A feeding trial was designed to assess the effects of dietary protein and lipid content on growth, feed utilization efficiency, and muscle proximate composition of juvenile mandarin fish, Siniperca scherzeri. Six experimental diets were formulated with a combination of three protein (35, 45, and 55%) and two dietary lipid levels (7 and 14%). Each diet was fed to triplicate groups of fish ($8.3{\pm}0.1g$) to apparent satiation for 8 weeks. The results showed that growth performance in terms of weight gain (WG) and specific growth rate (SGR) increased with increasing dietary protein level from 35 to 55% at the same dietary lipid level. At the same dietary lipid content, WG and SGR obtained with diets containing 55% protein was significantly higher than those obtained with diets containing 45 and 35% protein. No significant effect on growth rate was found when the dietary level of lipid was increased from 7 to 14%. While the levels of protein and lipid in the diets had no significant effect on feed intake, other nutrient utilization efficiency parameters including daily protein intake (DPI), feed efficiency (FE), and protein efficiency ratio (PER) showed a similar trend to that of growth rates, with the highest values obtained with diets containing 55% protein. Muscle chemical composition was not significantly affected by the different dietary treatments for each dietary lipid or protein level tested. These findings may suggest that a practical diet containing 55% protein and 7% lipid provides sufficient nutrient and energy to support the acceptable growth rates and nutrient utilization of mandarin fish juveniles.

• Journal of Nutrition and Health
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• v.24 no.1
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• pp.20-29
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• 1991

This study was carried out to compare the protein quality of lamb and beef meat. by feeding to growing rats. Sixty weanling rats, 30 males and 30 females, were blocked into 12 groups(6 gruops of males and 6 groups of females). They were fed casein. beef, or lamb as a protein source at two levels, 6 and 15%, for 5 weeks. The amount of food intake. food efficiency ratio, protein efficiency ratio. body weight gain. and the weights of skeletal muscles and liver were measured. Nitrogen retention, protein content in the liver and skeletal muscles, and the levels of protein and cholesterol in the serum were also assayed. Summarzing the results, there were no significant differences between lamb and beef on the growth and nitrogen utilization in the rats fed same percentage of protein diet. However. rats fed 15% protein diet showed significantly higher growth rate than those fed 6%. Therefore, it can be concluded that lamb is as good a protein food as beef in terms of protein quality.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.6
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• pp.718-724
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• 1998

Twelve gilts were used to investigate the effect of lysine to protein ratio (5.2 g lysine/100 g CP vs. 6.7 g lysine/100 g CP) in practical diets on nitrogen retention and the efficiency of utilization in growing pigs. Treatments involved 2 levels of dietary lysine (5.2 or 6.7 g/100 g CP) and 3 levels of dietary crude protein (11, 14 and 17% in diet). Nitrogen retention was greatest when pigs were fed the control diet containing 17% protein. Nitrogen retention progressively increased as dietary protein increased (p < 0.01), but it was not affected by lysine concentration (g/100 g CP). Apparent biological value (ABV, nitrogen retained/apparently digestible nitrogen) was estimated to be ~50% at the maximum nitrogen retention. ABV was not affected by lysine concentration, but declined (p < 0.05) as the dietary protein level increased. The efficiency of intake N used for maximum nitrogen retention was approximately 44%. One gram of lysine supported approximately 9 to 10 g apparent protein accretion (nitrogen retention ${\times}$ 6.25/lysine intake) in pigs fed control diets. The efficiency of lysine utilization for protein accretion was lower in pigs fed high-lysine diets (6.7 g lysine/l00 g CP) so that 1 g of lysine accounted for 7 to 8 g of protein accretion in these pigs (p < 0.01). The lysine required to support maximum nitrogen retention in pigs fed high-lysine diets was higher than that in pigs fed control diets, which suggests that lysine was over-fortified relative to crude protein, since practical diets can not be formulated without excess of some amino acids. In summary the concentration of 5.2 g total lysine/100 g CP in diet is more appropriate for corn-soybean diets than the commonly suggested the content of 6.7 g total lysine/100 g CP.

• Fisheries and Aquatic Sciences
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• v.7 no.4
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• pp.184-191
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• 2004

A 25-week feeding trial of two dietary protein (47 and $52\%$) and three dietary lipid level (7, 12 and $17\%$) factorial design with three replications were conducted to determine effects of dietary protein and lipid levels on growth, feed utilization and body composition of adult starry flounder (Platichthys stellatus), average initial weight 332 g, during the winter season. Survival of fish was not affected by either dietary protein or dietary lipid level. Weight gain, feed efficiency and protein efficiency ratio improved with dietary protein and lipid levels except for those of fish fed the $52\%$ protein diet with $17\%$ lipid. The best growth and feed utilization were observed in the $52\%$ protein diet with $12\%$ lipid, but were not significantly different from those of fish fed the $52\%$ protein diet with $17\%$ lipid or the $47\%$ protein diets with $17\%$ lipid levels. Hepatosomatic and visceral somatic indexes were significantly influenced by dietary protein level, but not by dietary lipid level. None of moisture, crude protein, crude lipid, or glycogen contents of dorsal muscle or liver in starry flounder except for crude lipid in dorsal muscle was significantly influenced by either dietary protein or dietary lipid level. Plasma cholesterol concentration was significantly influenced by both dietary protein and dietary lipid levels. The results of this study suggest that the diets containing $47\%$ protein with $17\%$ lipid or $52\%$ protein with $12-17\%$ lipid are optimal for growth and feed utilization of adult starry flounder under these experimental conditions.

• 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.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.10
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• pp.1417-1424
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• 2011

This study was conducted to assess the relation between threonine (Thr) oxidation rate and threonine efficiency on rat and chicken fed with graded levels of protein and threonine. The increase in threonine content from 0.28 to 0.72% in a diet containing 12.0% crude protein (CP) caused a gradual increase in threonine dehydrogenase (TDG) activity in rat liver. Similar, but more pronounced results were observed after 18.0% CP in the diet. Both protein levels in combination with the highest level of threonine supplementation increased liver TDG activity significantly, indicating enhanced threonine catabolism. Parameters of efficiency of threonine utilization calculated from parallel nitrogen balance studies decreased significantly and indicated threonine oversupply after a maximum of threonine supplementation. At the lower levels of threonine addition the efficiency of threonine utilization was not significantly changed. In the chicken liver up to 0.60% true digestible threonine (dThr) in the 18.5% CP diet produced no effect on the TDG activity. However, TDG activity in the liver was elevated by the diet containing 22.5% CP (0.60% dThr) and the efficiency of threonine utilization decreased, indicating the end of threonine limiting range. In conclusion, the in vitro TDG activity in the liver of rat and growing chicken has an indicator function for the dietary supply of threonine.

• Journal of Nutrition and Health
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• v.20 no.2
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• pp.122-134
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• 1987

In order to investigate the effect of dietary protein and fat levels on the growth and the utilization of nitrogen and energy and body composition in rats, Sprague\ulcornerDawley 48 male rats of 8 weeks old weighing approxijIlately 215-220g were subjected to feeding trials for 8 weeks and then subsequently to metabolic trials for 2 weeks. Four dietary protein levels (4, 8, 16, 32%) and each protein level contained two fat levels(3.9, 11.7%=1O,3J% of 3600kcal ME/kg) by addition of an appropriate amount of carbo\ulcornerhydrate and the following results were obtained. The body weight gain and food efficiency ratio of the rats to which a diet of 16% protein and 3.9% fat was fed were significantly higher than in either case of 8% pro\ulcornertein diet or of 32% protein diet. The digestibility of protein in the experimental diets was 73.3 -93.4%. The digesti\ulcornerbility of energy ( energy absorption) in the experimental diets was 83.2 -91.5%. The utilization of protein and the metabolic energy efficiency in the experimental diets was highest at the diet of 8% protein and 3.9% fat. The analysis of the body composition after feeding trials for 8 weeks has shown that the content of body water and protein were not affected by protein and fat levels in diet. The content of body fat in the rats to which 3.9% fat diet was fed was high\ulcornerer than that in those to which 11.7% fat diet was fed. From the above experimental results it may be suggested that the best formula of diet for the 8 weeks old rats may be composed of the 8% protein and 3.9% fat.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.2
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• pp.126-132
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• 1991

Nutritional factors affecting the urinary excretion of acid-soluble peptides(ASP) in rats were studied using protein-free diet, gluten diet, casein diet, and gluten supplemented with lysine and threonine(GLT) diet. The content of urinary ASP was lowest in protein-free diet group among the four kinds of diets above. But the amino acid pattern of urinary ASP in the four dietary groups were similar each other, suggesting that urinary ASP is mainly from endogenous origin under these nutritional conditions. The efficiency of dietary protein utilization was significantly lower in gluten diet than that of casein diet or GLT diet. Those findings suggest that the rate of urinary excretion of ASP-form amino acids can be employed as an index of protein metabolism, particularly as a simple index in the assessing the status of protein nutrition.

• Asian-Australasian Journal of Animal Sciences
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• v.1 no.1
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• pp.7-12
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• 1988

Twenty cows, by order of calving, were used in a completely randomized $2{\times}2$ factorial experiment. Variables were tow protein levels (14 and 18% crude protein) and concentration of fat (2 and 6% ether extract) in diets. Fat addition, via unprocessed whole sunflower seed, insured forage utilization in diets to meet energy requirement of cows. A total of 36 wks of lactation was subdivided into three 12-wk stages of lactation. Net energy lactation was set at 1.72, 1.57 and 1.42 Mcal/kg for each stage. Higher protein diets improved the efficiency of energy (FCM/net energy intake) which was particularly noted for diets containing high fat (85.7%). However, diets with low protein-high fat resulted in the lowest efficiency (67.7%). No difference in milk yield and butterfat was due to different levels and combinations of protein and lipid in diets. High protein diets depressed blood cholesterol and glucose compared to low-protein counterparts. Relative decline in milk production was slower for lower fat diets than for higher fat groups, especially mid to later stage of lactation. Results of this experiment tend to support our thesis on the synergistic effect of dietary protein and energy (lipid) upon efficiency of lactation.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.6
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• pp.725-731
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• 1998

Nine crossbred female pigs fitted with the bladder catheters were used to investigate the effects of dietary protein form on the efficiency of absorbed nitrogen for nitrogen retention in growing pigs. Combinations of the main protein sources were corn-soybean meal (CSM; slow + slow absorption rate form), corn-hydrolyzed casein (CAS; slow + rapid absorption rate form) and corn-porcine plasma (CPL; slow + intermediate absorption rate form). All experimental diets were formulated to be isonitrogenous (CP 11%) and isocaloric (3.5 Mcal/kg) and synthetic amino acids were added to the diet as required to maintain an equivalent amino acid profile among diets. Fecal digestibility of nitrogen was not different among treatments (p > 0.10). Ingested nitrogen was absorbed with an apparent efficiency of 82% to 84%. Mean nitrogen retention in pigs fed the CSM diet was as high as for pigs fed the CPL diet (0.74 g N/kg $BW^{0.75}$ per d), which was higher than the N retention rate in pigs fed CAS diet (0.68 g/kg $BW^{0.75}$ per d; P < 0.05). Apparent biological values (ABV = 100 ${\times}$ N retention/absorbed nitrogen) were 63.3%, 58.0% and 61.6% for CSM, CAS, and CPL groups, respectively (p < 0.05). There was no difference in mean energy digestibility among treatments. The efficiency of absorbed lysine utilization was significantly different among treatments (p < 0.05). Pigs fed the CAS diet were inferior to counterparts on the other diets in utilizing absorbed lysine. The ratios of free (and small peptide-bound) to protein-bound amino acids in CSM diet differed considerably from the CAS diet. This may affect the efficiency of amino acids utilization for nitrogen retention if hydrolyzed and intact amino acid pools reach the blood at different times.