Non-essential Amino Acid Ratio Research Articles

Effect of free ammonia shock on Chlorella sp. in wastewater: Concentration-dependent activity response and enhanced settleability

The unstable microbial activity and unsatisfactory settling performance impede the development and implementation of microalgal wastewater treatment, especially in high-ammonium wastewater in the presence of free ammonia (FA). The shock of FA due to the nutrient fluctuation in wastewater was demonstrated as the primary stress factor suppressing microalgal activities. Recent study has clearly revealed the inhibition mechanism of FA at a specific high level (110.97 mg/L) by inhibiting the genetic information processing, photosynthesis, and nutrient metabolism. However, the effects of various FA shock concentrations on microalgal activities and settling performance remain unknown, limiting the wastewater bioremediation efficiencies improvement and the process development. Herein, a concentration-dependent shock FA (that was employed on microalgae during their exponential growth stages) effect on microalgal growth and photosynthesis was observed. Results showed that the studied five FA shock concentrations ranging from 25 to 125 mg/L significantly inhibited biomass production by 14.7–57.0%, but sharp reductions in photosynthesis with the 36.0–49.0% decreased Fv/Fm values were only observed when FA concentration was above 75.0 mg/L. On the other hand, FA shock enhanced microalgal settling efficiency by 12.8-fold, which was believed to be due to the stimulated intra- and extracellular protein contents and thereby the enhanced extracellular polymer substances (EPS) secretion. Specifically, FA shock induced 40.2 ± 2.3% higher cellular protein content at the cost of the decreased carbohydrates (22.6 ± 1.3%) and fatty acid (39.0 ± 0.8%) contents, further improving the protein secretion by 1.21-fold and the EPS production by 40.2 ± 2.3%. These FA shock-induced variations in intra- and extracellular biomolecules were supported by the up-regulated protein processing and export at the assistance of excessive energy generated from fatty acid degradation and carbohydrates consumption. In addition, FA shock significantly decreased the biomass nutritional value as indicated by the 1.86-fold lower essential amino acid score and nearly 50% reduced essential to non-essential amino acids ratio, while slightly decreased the biodiesel quality. This study is expected to enrich the knowledge of microalgal activities and settling performance in response to fluctuant ammonium concentrations in wastewater and to promote the development of microalgal wastewater treatment.

Evaluation of Serum and Urine Amino Acids in Dogs with Chronic Kidney Disease and Healthy Dogs Fed a Renal Diet.

This observational study aimed to evaluate serum and urinary amino acid (AA) concentrations in healthy dogs and dogs with chronic kidney disease (CKD) fed a commercial therapeutic renal diet with reduced protein and phosphorus levels. Ten dogs with CKD stages 3 or 4 composed the study group and received the renal diet for 180 days (RG T180). A control group (CG T30) composed of seven healthy dogs was fed a renal diet for 30 days. When comparing serum AA between RG T180 and CG T30, histidine, isoleucine, leucine, lysine, phenylalanine, tryptophan, cysteine, citrulline, ornithine, taurine, branched-chain amino acids (BCAA), and total essential amino acids (EAA) were higher in RG T180. Meanwhile, arginine, asparagine, aspartate, glutamine, serine, and tyrosine were higher in CG T30. Serum phenylalanine, tryptophan, and hydroxyproline were higher in RG T0 (dogs with CKD before consuming a renal diet) when compared to RG T180. In addition, the serum ratios of arginine/citrulline, tyrosine/phenylalanine, and serine/glycine were higher in CG T30 than in RG T180. Concerning urinary AA concentrations in CKD dogs, isoleucine, phenylalanine, tryptophan, aspartate, cysteine, and BCAA were higher in RG T180. In urine, the total EAA/total non-essential AA ratio in RG T180 was higher than in CG T30 as well as tyrosine/phenylalanine ratio higher in CG T30. In conclusion, the combination of renal diet and conservative treatment over 6 months in dogs with CKD stages 3 or 4 affected the AAs metabolism when compared to healthy adult dogs.

Amino acids profile of catfish, crayfish and larva of edible <i>dung</i> beetle

Protein is an important nutrient for growth and development of humans and its quality depends on the types and composition of its amino acids. The amino acid profile of dung beetle larva was determined and compared with those of catfish and crayfish by HPLC using Applied PTH Biosystem amino acid analyzer. The data obtained were analyzed with inferential statistics of Analysis of Variance (ANOVA) and means separated using LeastSignificance Difference (LSD). The results showed that there were significant differences in the samples for all the set criteria for amino acid quality: total amino acid (F = 219.9), percentage amino acid (F = 1095.4), 2, 6 2, 6 essential amino acid score (F = 2588.4), essential to non-essential amino acid ratio (F = 236.7) and predicted 2, 6 2, 6 protein efficiency ratio (F = 1049.4) all at P < 0.05. About 66.7% of the essential amino acids in dung beetle 2, 6larva satisfy human nutritional requirement while amino acids like tryptophan, histidine and threonine were significantly higher in dung beetle. The amino acid score of this insect was higher as it has the potential of over 100% protein synthesis as against 68.2% and 80.9% respectively for catfish and crayfish. Moreover, a consumption of 46 g of dung beetle larva can effectively satisfy the daily human amino acid requirement. The study concluded that the protein quality of insects especially dung beetle larva compared favorably with commonly consumed human protein diets like catfish and crayfish. Therefore entomophagy should be encouraged in the face of the present dwindling availability of animal protein food sources.
 Keywords: Amino acid score, Entomophagy, Protein energy malnutrition, Dung beetle

Nutritional profiling of selected species of edible marine molluscs from the south-west coast of India

The current study determined the nutritional parameters of selected species of edible marine molluscs viz., Indian squid Uroteuthis (Photololigo) duvaucelii, veined octopus Amphioctopus marginatus, spineless cuttlefish Sepiella inermis and edible oyster Crassostrea bilineata (=madrasensis) from the Arabian Sea and estuarine systems of the south-west coast of India. The selected species demonstrated balanced essential to non-essential amino acids ratio (1.04-1.52). U. (P.) duvaucelii exhibited greater quantities of sulfur comprising amino acids (0.102 g 100 g-1 wet weight) and lysine (1.566 g 100 g-1). Among polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were found to be prominent in edible portion of the molluscs studied (7.6-10.3 and 8.7-17.4% respectively). A. marginatus exhibited significantly greater n-3/n-6 PUFA (~7, p<0.05) than other molluscs. Lower thrombogenicity and atherogenicity indices (<0.45 and <0.85, respectively) make the mollusc studied during the present investigation valuable food items for cardioprotection and anti-platelet aggregation. Higher content of vitamin D3 (489 IU) and vitamin K1 (1.84 μg 100 g-1) in C. bilineata signified their importance in preventing osteoporosis. The results reveal that these species are good sources of essential elements and toxic metals were below threshold limits of recommended standards for human consumption.

Nutritional Qualities of the Low-Value Bivalve Mollusks Paphia malabarica and Villorita cyprinoides at the Estuarine Waters of the Southwestern Coast of India

ABSTRACTThe bivalve mollusks Paphia malabarica and Villorita cyprinoides collected from the estuarine system located in the southwest coastal waters of India were evaluated for their nutritional composition. A balanced essential to nonessential amino acid ratio (> 1.0) with a greater quantity of sulfur-containing amino acids in these species demonstrated that they could provide well-balanced protein depositions. The n-3/n-6 polyunsaturated fatty acid ratio in P. malabarica was found to be greater than 2, and, therefore, can be considered as a healthy diet. The C20–C22 long-chain polyunsaturated n-3 fatty acids (for example, docosahexaenoic acid and eicosapentaenoic acid) accounted for more than 23% of the total fatty acid content in P. malabarica as compared to about 7% in V. cyprinoides. P. malabarica showed greater hypocholesterolemic/hypercholesterolemic ratio (1.7) and lesser atherogenicity (0.7), thrombogenicity (0.3) indices when contrasted with those in V. cyprinoides, thereby indicating the nutritional superiority of the former. A greater content of vitamin D3 (> 150 IU), along with significant quantities of calcium and phosphorus (> 500 mg/100 g) in the clams, signified their importance in preventing osteoporosis. This study demonstrated the importance of bivalves, in particular, P. malabarica as a valued species for human consumption.

Nutritional attributes in the fillet of skipjack tuna (Katsuwonus pelamis) from the Arabian Sea near the south-west coast of India

Inter-annual and seasonal variability in the nutritional parameters of the edible portion of skipjack tuna (Katsuwonus pelamis) collected from the Arabian Sea were determined for a period of 4 years. Greater levels of long chainn-3 fatty acids (35% during pre-monsoon), critical in the human diet for their anti-inflammatory properties with greatern-3:n-6 fatty acid ratio (8:12) demonstrated that this species may serve as an alternative to balance the greater amount ofn-6 fatty acids. The present study demonstrated skipjack tuna as a significant source of protein, amino acids, minerals and vitamins. A balanced essential to non-essential amino acid ratio (1.2:1.4) in the fillets indicated that this species could provide well-balanced protein depositions. Vitamins A and K1demonstrated post-monsoon maxima, whilst vitamins D3and E showed pre-monsoon maxima. Greater calcium (172 mg 100 g−1) and phosphorus contents (923 mg 100 g−1) were recorded in the fillets of skipjack tuna during the pre-monsoon season. The chlorophyll-a concentration and sea surface temperature of its habitat were considered to understand their effect on the nutritional composition of skipjack tuna all through the study period. Significant correlation between long chainn-3 polyunsaturated fatty acids such as eicosapentaenoic acid and docosahexaenoic acid (r2~ 0.99) of skipjack tuna alongside chlorophyll-a concentration was observed, particularly during the monsoon. The lesser atherogenic/thrombogenicity indices (<1), greater hypocholesterolaemic/hypercholesterolaemic ratio (>1.0), and lesser cholesterol contents (<50 mg 100 g−1) of the fillets in skipjack tuna contributed towards its parameters to be qualified as a high value, balanced nutritional source.

Nutritional and Antioxidative Attributes of Green Mussel (Perna viridis L.) from the Southwestern Coast of India

ABSTRACTThe present study reports the biochemical composition of Perna viridis from the southwestern coast of India. A balanced essential to nonessential amino acid ratio (0.7:1.1) along with the optimum and balanced quantities of vitamins, mineral nutrients, and low cholesterol contents characterized P. viridis. The n-3/n-6 polyunsaturated fatty acid ratio of P. viridis was found to be 3.7:5.3 and therefore may serve as an alternative to balance the higher intake of n-6 fatty acids. High oxyradical scavenging capacity (24–32%) and total phenolics (2–5 mg GAE−1) suggest the nutraceutical potential of P. viridis.

Nutrient composition and antioxidant activity of gonads of sea urchin Stomopneustes variolaris

The study investigated, for the first time, proximate nutritional composition and antioxidant activity of gonads from the sea urchin, Stomopneustes variolaris, inhabiting the coastal area of Visakhapatnam (India). Moisture, ash, proteins, lipids and carbohydrate content were 77.53%±0.80, 3.76%±0.25, 12.10%±0.41, 4.98%±0.36 and 1.63%±0.18, respectively, based on dry weight. The gonads were rich in essential amino acids (ca. 32.1% of total amino acids) with the most predominant being phenylalanine, lysine and valine. The essential to non-essential amino acid ratio was 0.5. Polyunsaturated fatty acids (PUFA) constituted 22.01%±2.2 of total fatty acids. The ω6:ω3 ratio was 0.94. Total phenol content of the gonad was 9.90±0.01mg GAE/g and the IC50 of the extract, using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, was 57.81μg/ml.

Reduction of the crude protein content of diets supplemented with essential amino acids for piglets weighing 15 to 30 kilograms

Two experiments were carried out to evaluate the reduction of crude protein (CP) in diets supplemented with synthetic amino acids for piglets of 15 to 30 kg. In the performance assay (Exp I), 60 piglets with initial weight of 15.34±0.87 kg and final weight of 30.08±1.59 kg were distributed in a randomized block design with six replicates, five treatments and two animals per experimental unit. The treatments consisted of five diets in which the CP was reduced by 1.5 percentage points, resulting in low-protein diets (19.24, 17.74, 16.24, 14.74 and 13.24%), meeting the requirements of amino acids with inclusion of L-lysine, DL-methionine, L-threonine, L-tryptophan, L-valine and L-isoleucine. The average daily gain and feed conversion according to the Linear Response Plateau model (LRP) were estimated at 14.23 and 14.79% of CP, respectively. As the CP levels were reduced, there was an increase in the essential:non-essential amino acids ratio. The plasma urea concentration decreased linearly, indicating that there was a better use for amino acids with the CP reduction. In the nitrogen balance (Exp II), 30 crossbred barrow piglets with average weight of 21.69±4.46 kg were housed in metabolic cages, distributed in a completely randomized design with five treatments and six replicates, and the experimental unit consisted of a piglet. The biological protein value in the diets remained above the ideal (70%), in which the level of 13.24% CP corresponded to the highest value. There was no difference in levels of urea in blood and urine. Reduction of protein levels is efficient in decreasing the pollution effect in the excreta, with lower nitrogen excretion in feces and urine.

Inter Annual and Seasonal Dynamics in Amino Acid, Vitamin and Mineral Composition of Sardinella longiceps

Sardinella longiceps were studied for the spatial (south west (SW) and southeast (SE) coast of India), annual (2008, 2009, 2010 and 2011) and seasonal (pre-monsoon, monsoon and post-monsoon) variations of protein, amino acids, minerals and vitamins. The chlorophyll-a concentration and sea surface temperature of its habitats were taken into account to understand their effect on the nutrient signatures of oil sardine throughout the study period and locations. Mean protein content attained its maximum during pre-monsoon along both SW and SE coasts, with high proportions of essential amino acids. Essential to non-essential amino acid ratio, total aromatic (TArAA) and total sulfated amino acids (TSAA) recorded monsoon maxima along the study locations. Amino acid scores observed monsoon and post-monsoon maxima along the SW and SE coast, respectively. Minerals were significantly higher during monsoon along the SE coast (P<0.05). Significant seasonal variations in vitamin content were observed along the study locations with high vitamin A, D3 and C on SW coast and higher vitamin E and K in SE coast. The present study demonstrated Sardinella longiceps as a valuable source of the protein, amino acids, minerals and vitamins. A reasonably good ratio of essential to nonessential amino acids for oil sardines was recorded throughout different study period and locations, and therefore it can be concluded that this low-value species is an excellent source of good balanced proteins with high-biological value to be qualified as a preferred health food for human diet.

양식산 넙치(Paralichthys olivaceus)의 식품학적 품질 개선에 버섯추출물이 미치는 영향

This study investigated the nutritive quality of olive flounder Paralichthys olivaceus fed either moist pellet (MP) or moist pellet mixed with mushroom extract (MPME) for 6 months. There was no significant difference in crude protein or extractive nitrogen in the muscle of flounder fed MP versus MPME (P > 0.05). The total amino acid content in the muscle of flounder fed MP was <TEX>$15.22{\pm}5.24$</TEX> g/100 g, compared to <TEX>$19.90{\pm}2.90$</TEX> g/100 g for flounder fed MPME. Essential amino acid content was <TEX>$7.04{\pm}2.21$</TEX> g/100 g in the muscle of flounder fed MP versus <TEX>$8.94{\pm}2.50$</TEX> g/100 g for MPME. Total amino acid content was higher in the muscle of olive flounder fed MPME, while essential amino acid content was higher in flounder fed MP. The ratio of non-essential amino acids to essential amino acids was <TEX>$0.86{\pm}0.07$</TEX> for flounder fed MP and <TEX>$0.81{\pm}0.08$</TEX> for flounder fed MPME. There was no significant difference in free amino acid content and fatty acid composition. The breaking strength of muscle of olive flounder fed MP was higher (<TEX>$1.44{\pm}0.51\;kg/cm^2$</TEX>) than in flounder fed MPME (<TEX>$1.29{\pm}0.30\;kg/cm^2$</TEX>). There was no evidence that dietary additives, such as mushroom extract, increase growth rate or nutritive quality of olive flounder.

Improved plasma amino acids pattern following 12 months of supplemented low-protein diet in peritoneal dialysis patients

Background: Decreased plasma essential amino acid (EAA) levels, increased nonessential amino acid (NEAA) levels, and low EAA to NEAA ratio (E/NEAA) are common in peritoneal dialysis (PD) patients and may impact uremic complications. In the present study, we investigate the impact of keto acids–supplemented low–protein (sLP) diet on plasma amino acids (AAs) patterns in stable PD patients. Methods: This is a supplemental analysis of a previously published prospective and randomized trial. Thirty-nine PD patients selected from the original population were divided to receive either low (LP: 0.6–0.8 g/kg ideal body weight [IBW]/d, n = 13), keto acids–supplemented low- (sLP: 0.6–0.8 g/kg IBW/d + 0.12 g/kg IBW/d of keto acids, n = 12), or high- (HP: 1.0–1.2 g/kg IBW/d, n = 14) protein diets and followed for 1 year. Plasma AA patterns were assessed at baseline and 12 months using high-performance liquid chromatography. Results: Whereas there were no significant differences between the three groups at baseline, following 12 months, the E/NEAA had increased significantly in group sLP (0.58 ± 0.16 to 0.83 ± 0.20, p < 0.05), but was not different in either LP (0.62 ± 0.20 to 0.72 ± 0.13, p = ns) or HP (0.66 ± 0.14 to 0.74 ± 0.12, p = ns) group. This change in E/NEAA in group sLP was due to a significant decrease in NEAA concomitantly with maintained EAA levels, whereas in the other two groups, neither EAA nor NEAA changed significantly. Conclusions: A low-protein diet supplemented with keto acids significantly improved the pattern of plasma AA in prevalent PD patients.

Effect of the dietary essential to non-essential amino acid ratio on growth, feed utilization and nitrogen metabolism of European sea bass ( Dicentrarchus labrax)

A study was undertaken to evaluate if dietary essential to non-essential amino acid ratio (EAA/NEAA) affects growth, feed utilization and nitrogen metabolism of European sea bass. Three semi-purified diets including fish meal and mixtures of crystalline amino acids as the main nitrogen (N) sources were formulated to have a dietary EAA/NEAA ratio of 40/60, 50/50 and 60/40; another diet, fish meal based was used as a control. All diets were formulated to be isolipidic (15% DM) and isonitrogenous (8% DM). Triplicate groups of juvenile sea bass (initial body weight of 7.3 g) were fed each diet, twice daily to apparent satiation, for 42 days. Weight gain and specific growth rate of fish fed the control, 60/40 and 50/50 diets were similar and significantly higher than those of fish fed the 40/60 diet. Voluntary feed intake of fish fed the 60/40 diet was significantly lower than that of fish fed the 50/50 and 40/60 diets. Feed efficiency and protein efficiency ratio significantly improved with the increase of dietary EAA/NEAA ratio. Whole-body composition, visceral and hepatosomatic indices were not significantly affected by diet composition, except whole-body lipid content that was significantly lower in fish fed the 40/60 diet than in the other groups. Daily N retention (g kg ABW − 1 ) was significantly lower with the 40/60 diet than with the other diets. As percentage of N intake, N retention was significantly higher with the 60/40 diet than with the other diets. Energy retention (kJ kg ABW − 1 day − 1 and % of E intake) significantly increased as dietary EAA/NEAA increased. Ammonia-N and urea-N excretion (mg N kg ABW − 1 day − 1 ) did not differ significantly among treatments. Ammonia-N excretion (% N intake) was significantly higher with diet 40/60 than with the other diets. Specific activity of glutamate dehydrogenase was significantly lower in fish fed the control and 60/40 diets than in the other groups. Specific activity of alanine and aspartate aminotransferases and glucose-6-phosphate dehydrogenase did not significantly differ among groups. Fatty acid synthetase activity was significantly higher with the 40/60 diet than with the other diets. Results of this study suggest that a dietary EAA/NEAA ratio of 50/50 is necessary to promote maximum growth performance of juvenile European sea bass. However, this ratio should be increased to 60/40 if maximization of feed, protein and energy utilization is to be considered.

Phloem-sap feeding by animals: problems and solutions

The incidence of phloem sap feeding by animals appears paradoxical. Although phloem sap is nutrient-rich compared with many other plant products and generally lacking in toxins and feeding deterrents, it is consumed as the dominant or sole diet by a very restricted range of animals, exclusively insects of the order Hemiptera. These insects display two sets of adaptations. First, linked to the high ratio of non-essential:essential amino acids in phloem sap, these insects contain symbiotic micro-organisms which provide them with essential amino acids. For example, bacteria of the genus Buchnera contribute up to 90% of the essential amino acids required by the pea aphid Acyrthosiphon pisum feeding on Vicia faba. Second, the insect tolerance of the very high sugar content and osmotic pressure of phloem sap is promoted by their possession in the gut of sucrase-transglucosidase activity, which transforms excess ingested sugar into long-chain oligosaccharides voided via honeydew. Various other animals consume phloem sap by proxy, through feeding on the honeydew of phloem-feeding hemipterans. Honeydew is physiologically less extreme than phloem sap, with a higher essential:non-essential amino acid ratio and lower osmotic pressure. Even so, ant species strongly dependent on honeydew as food may benefit from nutrients derived from their symbiotic bacteria Blochmannia.

The Relationship between Changes in Serum Glycine and Alanine Concentrations in Non-Essential Amino Acid and Milk Production in the Transition Period in Dairy Cows

The serum concentration of non-essential amino acid (NEAA) was measured in ten Holstein dairy cows grouped as low production (n=5) and high production (n=5) from one month pre-partum through four months post-partum and the relationship between production and amino acid concentrations was studied. The glycine (Gly)/NEAA ratio and the glycine/alanine ratio of the high production group were significantly higher than the low production group (p<0.01). The observed decrease of the alanine (Ala)/NEAA ratio was more remarkable in the high production group than in the low production group. Measurement of Gly/Ala ratio in serum may be useful for evaluating the nutritional status of peri-parturient dairy cow.

The optimum dietary essential: nonessential amino acid ratio for rainbow trout (Oncorhynchus mykiss), which maximizes nitrogen retention and minimizes nitrogen excretion

Although the ratio of essential to nonessential amino acids (EAA:NEAA ratio) in dietary protein has important effects on protein utilization by fish, there has thus far been little research aimed at quantifying these effects. In this study, we investigated the effect of dietary EAA:NEAA ratio on nitrogen (N) utilization and excretion of rainbow trout (Oncorhynchus mykiss). A 6-week dose-response experiment was conducted, with 6 levels of dietary EAA:NEAA ratio, ranging from 23:77 to 66:34. Protein content of all diets was 350 g kg−1. Each experimental diet was fed to four replicate tanks of fish (35 fish per tank). Fish were fed a limited ration on the first two feedings of each day, and were fed to apparent satiation on the third feeding of each day. Response variables included feed intake, weight gain, lipid deposition, thermal-unit growth coefficient (TGC), feed efficiency ratio (FER), N retention, and N excretion (g kg−1 gain). Mean feed intake, weight gain, TGC, FER and N retention all increased as EAA:NEAA ratio increased up to 57:43, and then decreased slightly as EAA:NEAA ratio increased further to 66:34. Maximum mean N retention of 46% and minimum mean N excretion of 29 g N kg−1 gain was achieved by fish fed the diet containing an EAA:NEAA ratio of 57:43. Non-linear regression using a 2nd order polynomial equation showed that 95% of the maximum N retention could be achieved with an EAA:NEAA ratio of 46:54, and 98% with an EAA:NEAA ratio ranging from 49:51 to 62:38.

Non-essential amino acid sources in crystalline amino acid diets for trout (Oncorhynchus mykiss)

A study was conducted over a 84-day period to evaluate glycine, L-glutamic acid and L-glutamine as sources of non-essential amino acids (NEAA) in dietary ‘protein’ consisting of crystalline amino acids only. The study was performed with a total of 1200 rainbow trout fingerlings (Oncorhynchus mykiss) of 48 g mean body mass. The addition of non-essential amino acids (NEAA) to essential amino acids (EAA) evidently improved growth and feed efficiency: glutamine was superior to glycine and glycine superior to glutamic acid. However, the best results in growth were obtained by adding a mixture of all three NEAA. The improvement of trout performance by glutamine may hypothetically be traced back to a better amino acid absorption capacity by a less acidic intestinal milieu. In consequence, the optimal EAA to NEAA ratio may have to be redefined.

THE EFFECT OF THE ESSENTIAL TO NONESSENTIAL AMINO ACID RATIO ON TURKEY PERFORMANCE AND CARCASS COMPOSITION

The effect of altering the proportion of dietary protein supplied as essential amino acids (EAA) on the performance and carcass characteristics of young turkeys (to 3 wk of age) was investigated at three dietary protein levels (22, 26 and 30%) using semipurified diets. Four ratios of EAA to nonessential amino acids (NEAA) were employed (70:30, 60:40, 50:50 and 40:60) at each dietary protein level. Maxima in weight gain, percent and total carcass protein and feed intake were observed when EAA supplied 60% of total protein (i.e., the 60:40 ratio) at each protein level. The differences in weight gain and total carcass protein were largely attributed to differences in feed intake, since feed conversion efficiency was relatively unaffected by altering the EAA: NEAA ratio. More specifically, weight gain was shown to be limited by total protein intake. Since weight gain was maximized at the 60:40 ratio diets (in which all EAA are supplied at 128% of requirement) at least one of the EAA requirement values is incorrect. Key words: Turkeys, essential amino acids, protein requirement

Influence du jeûne protéique de longue durée sur la teneur en acides aminés sanguins et musculaires du rat

The influence of a protein-free diet in adult male rats has been evaluated for a 6-week period. Nitrogen retention, hepatic protein and free amino acid content in blood and muscle were determined as adaptation criteria. Long-lasting protein depletion did not modify the pattern of response affering in a shorter period: i.e. sparing of nitrogen and use of endogenous amino acids for protein synthesis. Except for lysine, arginine and histidine, the essential amino acids decreased in blood and the non-essential acids increased. The final effect was a decrease of the essential to non-essential amino acid ratio and a decrease in all amino acids in muscle.