Levels Of L-threonine Research Articles

Silica aggravates pulmonary fibrosis through disrupting lung microbiota and amino acid metabolites

Silicosis, recognized as a severe global public health issue, is an irreversible pulmonary fibrosis caused by the long-term inhalation of silica particles. Given the intricate pathogenesis of silicosis, there is no effective intervention measure, which poses a severe threat to public health. Our previous study reported that dysbiosis of lung microbiota is associated with the development of pulmonary fibrosis, potentially involving the lipopolysaccharides/toll-like receptor 4 pathway. Similarly, the process of pulmonary fibrosis is accompanied by alterations in metabolic pathways. This study employed a combined approach of 16S rDNA sequencing and metabolomic analysis to investigate further the role of lung microbiota in silicosis delving deeper into the potential pathogenesis of silicosis. Silica exposure can lead to dysbiosis of the lung microbiota and the occurrence of pulmonary fibrosis, which was alleviated by a combination antibiotic intervention. Additionally, significant metabolic disturbances were found in silicosis, involving 85 differential metabolites among the three groups, which are mainly focused on amino acid metabolic pathways. The changed lung metabolites showed a substantial correlation with lung microbiota. The relative abundance of Pseudomonas negatively correlated with L-Aspartic acid, L-Glutamic acid, and L-Threonine levels. These results indicate that dysbiosis in pulmonary microbiota exacerbates silica-induced fibrosis through impacts on amino acid metabolism, providing new insights into the potential mechanisms and interventions of silicosis.

L-threonine requirement of silver catfish (Rhamdia quelen): growth performance, body composition, plasma and liver metabolites

ABSTRACT A feeding trial was performed to evaluate the effects of dietary L-threonine supplementation on growth and body composition of fingerlings Rhamdia quelen (initial weight: 4.47 ± 0.39 g). Five diets (370 g/kg crude protein and 14.23 MJ / kg of digestible energy) containing levels of L-threonine (16.0, 22.0, 28.0, 34.0, 40.0 g threonine/kg protein) were fed to quadruplicate groups of fishes for 10 weeks. The analysed variables were influenced by the threonine levels. Fish fed with diet containing 16.0 g threonine/kg of CP showed lower growth and body deposition of nutrients. In addition to unsatisfactory performance, the fish subjected to lower levels of threonine presented higher hepatosomatic index scores and changes in the concentrations of some plasmatic metabolites. To determine the ideal level of threonine in the diet, the weight gain, specific growth rate and feed conversion ratio were subjected to broken-line and quadratic regression. The results showed indicate that a diet containing inadequate levels of threonine causes insufficient growth. Dietary threonine requirement of R. quelen was estimated between 24.5 and 32.5 g threonine/ kg of crude dietary protein, corresponding to 9.1 and 12.0 g/ kg threonine in the diet for the initial growth of silver catfish.

Long-Term Dietary Lycium ruthenicum Murr. Anthocyanins Intake Alleviated Oxidative Stress-Mediated Aging-Related Liver Injury and Abnormal Amino Acid Metabolism.

In recent years, the relationship between Lycium ruthenicum Murr. anthocyanins (LRA) and health has attracted increasing attention. The purpose of this study is to investigate the anti-aging effect and mechanism of LRA through a D-galactose (DG)-induced aging rat model. Our results showed that the long-term intake of LRA, for 8 weeks, improved motor function, reduced serum aging markers, promoted the endogenous antioxidant system, and suppressed the serum inflammatory cytokines in aging rats. Besides, the LRA treatment alleviated DG-induced liver injuries by relieving the inflammation and inhibiting Fas/FasL-mediated cell death. More importantly, the abnormal serum metabolome profiles of the aging rats were restored by the LRA, relating to 38 metabolites and 44 pathways. Specifically, the LRA significantly affected the amino acid and protein-related metabolic pathways by regulating the levels of L-threonine, L-aspartic acid, glycine, L-histidine, D-homocysteine, L-homocitrulline, L-homoserine, guanidineacetic acid, and kynurenine. These results have important implications for the development of LRA as an anti-aging and liver-protective ingredient.

Effect of L-threonine and NSP-degrading Enzyme on the Performance, Intestinal Morphometry and Immunocompetence of the Broiler Chickens Fed Wheat-based Diet during the Starter Period

This study was conducted to evaluate the effects of supplemental L-threonine and enzyme in a wheat-based starter diet (WBD) on the growth performance, intestinal morphology, and immune responses of male ROSS 308 broiler chickens. A total of 240 one-day-old chicks were allocated to six different dietary treatments in a completely randomized design with a 2×3 factorial arrangement. The treatments were two WBD (with or without enzyme) each supplemented with three levels of L-threonine (100%, 120%, and 140% of the NRC recommendation). To evaluate the humoral immune system, sheep red blood cells (SRBC) antigen was injected, and for evaluation of cutaneous basophil hypersensitivity (CBH) response, the phytohemagglutinin-P was injected subcutaneously. On day 21, two chicks were selected out of each replicate and were bled, slaughtered, and then their internal organs were dissected and weighed. Blood samples were used for malondialdehyde (MDA) measurement. Jejunal and ileal contents and tissues were sampled for the viscosity and morphometric measurements. The supplemental L-threonine at the level of 120% of the NRC recommendation improved body weight gain, feed conversion ratio, and anti-SRBC titer (P 0.05). The enzyme supplementation decreased the viscosity of jejunal contents and increased the villus height to crypt depth ratio in the jejunum (P < 0.05). In conclusion, it seems that more dietary L-threonine is needed to support the performance and health of the broilers when fed the WBD. However, no synergism was observed when L-threonine and enzyme supplementation were simultaneously applied in this study.

THE BOBY DIMENSIONS OF LOCAL CHICKENS AT THE PULLET PHASE AFTER L-THREONINE AND L-TRYPTOPHAN SUPPLEMENT IN FED

ABSTRACT&#x0D; &#x0D; The purpose of this experiment was to know the body dimensions of Kampong chickens at the pullet phase after l-threonine and l-tryptophan supplement in the feed. This experiment was conducted in Kelurahan Sasi and the Laboratory of Agricultural Faculty, University of Timor, Kefamenanu from July 2019 to September 2019. The experiment used 96 fourteen-week kampong chickens, was designed with a Completely Randomized Design, consisting of 4 treatments and 4 replications. The dietary treatments were T0 (control feed), T1 (supplementation of 0.15% l-threonine and 0.06% l-tryptophan), T2 (supplementation of 0.37% l-threonine and 0.11% l-tryptophan), and T3 (supplementation of 0.50% l-threonine and 0.15% l-tryptophan). The variables measured were body weight, chest circle, sternum length, wing length, back length, femur, tibia, and shank circle. Data obtained was analyzed by analysis of variance and Duncan’s test. The result showed that the bodyweight of T0, T1, T2, and T3 were 1542.83±10.54, 1600.03±1.82, 1638.49±14.97, and 1716.85±23.84 g/bird, respectively. The chest circle, wing length, back length, sternum length, femur, tibia, circle and length of shank were 26.20±1.87, 26.38±0.47, 28.63±2.21, and 29.83±1.83 cm/bird; 17.78±1.00, 17.98±0.36, 18.75±0.95, and 19.85±1.63 cm/bird; 15.75±0.64, 16.50±1.08, 18.50±0.57, and 18.38±0.85 cm/bird; 12.93±1.77, 13.75±1.19, 13.88±0.85, and 14.73±0.48 cm/bird; 10.50±0.70, 10.93±1.20, 10.95±0.10, and 11.73±0.73 g/bird; 10.70±0.50, 11.10±0.89, 12.23±0.58, and 12.15±0.57 cm/bird; 4.23±0.05, 4.20±0.21, 4.23±0.22, and 4.40±0.20 cm/bird; and 8.90±0.11; 8.88±0.47; 9.13±0.62, and 10.38±0.62 cm/bird, respectively. Statistical analysis showed that levels of l-threonine and l-tryptophan significantly affected body weight, chest circle, sternum length, wing length, and back length (P&lt;0,05). It was concluded that supplementation with 0.50% l-threonine and 0.15% l-tryptophan to the diet increases the body dimensions kampong chickens at the pullet phase.

A reliable LC-MS/MS method for the quantification of natural amino acids in mouse plasma: Method validation and application to a study on amino acid dynamics during hepatocellular carcinoma progression

A simple and fast LC-MS/MS method was developed and validated for simultaneous quantification of 20 proteinogenic l-amino acids (AAs) in a small volume (5 μL) of mouse plasma. Chromatographic separation was achieved on an Intrada Amino Acid column within 13 min via gradient elution with an aqueous solution containing 100 mM ammonium formate and an organic mobile phase containing acetonitrile, water and formic acid (v:v:v = 95:5:0.3), at the flow rate of 0.6 mL/min. Individual AAs and corresponding stable-isotope-labeled AAs internal standards were analyzed by multiple reaction monitoring (MRM) in positive ion mode under optimized conditions. Method validation consisted of linearity, sensitivity, accuracy and precision, recovery, matrix effect, and stability, and the results demonstrated this LC-MS/MS method as a specific, accurate, and reliable assay. This LC-MS/MS method was thus utilized to compare the dynamics of individual plasma AAs between healthy and orthotopic hepatocellular carcinoma (HCC) xenograft mice housed under identical conditions. Our results revealed that, 5 weeks after HCC tumor progression, plasma l-arginine concentrations were significantly decreased in HCC mice while l-alanine and l-threonine levels were sharply increased. These findings support the utilities of this LC-MS/MS method and the promise of specific AAs as possible biomarkers for HCC.

Threonine to lysine ratio in diets of tambaqui juveniles (Colossoma macropomum)

The objective of this study was to determine the optimal digestible threonine to lysine ratios in diets of tambaqui (Colossoma macropomum) juveniles. Five-hundred fish with a mean ± SE initial weight of 2.16 ± 0.03 g were used in a completely randomized design, consisting of four treatments, five replicates per treatment, and 25 fish per experimental unit. The treatments consisted of four isoenergetic, isophosphoric, isocalcic, and isolisinic (1.45%) diets, consisting of a basal diet supplemented with four L-threonine levels (1.013, 1.085, 1.158, and 1.230%), resulting in different threonine to lysine ratios (70, 75, 80, and 85%). Fish were maintained in twenty 500-L aquaria with independent water supply, drainage, and aeration systems, and were fed to apparent satiation six times a day for 45 days. Performance, feed efficiency, daily protein and fat deposition, body moisture content, and nitrogen retention efficiency of fish were evaluated. The digestible threonine intake increased linearly, and the efficiency of threonine for weight gain decreased quadratically, with increasing digestible threonine to lysine ratios. Weight gain, specific growth rate, feed:gain ratio, protein efficiency for weight gain, and nitrogen retention efficiency of fish increased in a quadratic manner with increasing digestible threonine to lysine ratios up to the levels of 75.96, 76.06, 76.36, 76.47, and 74.02%, respectively. It was concluded that the digestible threonine to lysine ratio for use in diets of juvenile tambaqui to achieve optimal performance and nitrogen retention efficiency is 76 and 74%, respectively, which corresponds to a digestible threonine level of 1.102 and 1.073%.

Effects of dietary L-threonine levels on antioxidant capacity, digestive enzyme activities, and antibody production of Xinyang green-shell laying hens

Xinyang green-shell laying hens (n = 720), 32 wk of age were allocated to 5 dietary treatments groups, each of which included 6 replicates of 24 hens. The control group was given a basal corn-peanut-soybean meal diet containing 0.47% L-threonine (L-Thr). L-Thr levels of the experimental groups were 0.57, 0.67, 0.77, and 0.87%, respectively. The trial lasted 10 wk. Serum concentrations of total superoxide dismutases (T-SOD) and superoxide dismutases (SOD) were maximized at 0.67% L-Thr group. The 0.57% L-Thr group had the highest serum total antioxidative capacity (T-AOC), while the 0.67% L-Thr group had the lowest serum malondialdehyde (MDA) concentration. Hens fed 0.67% L-Thr of the diet resulted in the highest SOD and T-AOC levels in the liver. The activity of amylase and lipase in the jejunum was maximized at 0.77% L-Thr level. Hens fed 0.77% L-Thr in the diet resulted in the highest IgM and IgG levels in the jejunum. In conclusion, we suggest that a L-Thr level above 0.67% may have had an antioxidant capacity and positive effect on digestive enzyme activities and antibody production in the jejunum of Xinyang green-shell laying hens.

Effects of Dietary Threonine Levels and Stocking Density on the Performance, Metabolic Status and Immunity of Broiler Chickens

ABSTRACT A total of 240 Cobb 500 broiler chic ks, 18 days old, were allocated to 10 treatments groups, eachof which included 4 replicates. Experimental treatments consisted of a 5×2 factorial arrangementwith 5 levels of L-threonine (Thr) supplementation and 2 levels of stocking density (11.90 birds m G 2 as the normal stocking density or 16.66 birds mG 2 as the high stocking density). L-Thr was addedto a basal diet at 0.0 (control group), 0.25, 0.50, 0.75 and 1.00 g kgG 1 diet. Dietary Thr values were0.69, 0.71 (deficient), 0.74 (adequate; 100% NRC), 0.76 and 0. 79% (excess) of the current NRCrecommendations. At 42 days of age, dietary Thr levels had no significant effect on performance,immunity, plasma total protein and glucose (GLU). However, plasma cholesterol (CHO) levelsdecreased significantly (p<0.05) with L-Thr supplementation and the lowest value occurred at0.74% total dietary Thr. In addition, plasma triio dothyronine (T3) and thyroxine (T4) levels werehigher (p<0.05) at 0.76% total dietary Thr comp ared with the control group. The normal stockingdensity resulted in better performance (p<0.05) co mpared with the high stocking density. However,stocking density did not affect plasma total protein, total Ig, IgG, IgM, total lipids, GLU, CHO, T3and T4 levels. Interactions between Thr level and stocking density were observed for plasmalevels of total lipids and cholesterol. In conclusion, total dietary Thr level at 0.69% (93% of NRCrecommendations) is sufficient to improve broiler performance or immunity under high stockingdensity. However, 0.74% total dietary Thr level has a positive effect on decreasing plasma totallipids and cholesterol levels during growing-finishing phase.

A fast and sensitive coupled enzyme assay for the measurement of l-threonine and application to high-throughput screening of threonine-overproducing strains

Amino acids are important fermentation products that are used in the food, animal feed, pharmaceutical, and cosmetics industries. Development of a better quantitation assay to measure amino acid levels will facilitate research and application in medical and industrial fields. Here we report the development of an assay that allows the rapid measurement of threonine concentration. l-threonine aldolase (LTA) catalyzes the cleavage of threonine to glycine and acetaldehyde. The resulting acetaldehyde is further converted into ethanol by alcohol dehydrogenase accompanying NADH reduction. Therefore, monitoring the changes in NADH concentration can serve as a readout for the amount of threonine present within certain range. This LTA assay can distinguish a 0.5mM difference in threonine concentration in some certain mediums. We successfully utilized this assay to measure l-threonine levels in industrial fermentation samples. Moreover, we were able to scale up this assay to 96-well format and use it in high-throughput screening of threonine-overproducing strains. We show this assay is simple, accurate, specific and suitable for determination of threonine concentration in large numbers of samples.

Modification of glycolysis and its effect on the production ofl-threonine inEscherichia coli

High concentrations of acetate, the main by-product of Escherichia coli (E. coli) high cell density culture, inhibit bacterial growth and L-threonine production. Since metabolic overflux causes acetate accumulation, we attempted to reduce acetate production by redirecting glycolysis flux to the pentose phosphate pathway by deleting the genes encoding phosphofructokinase (pfk) and/or pyruvate kinase (pyk) in an L-threonine-producing strain of E. coli, THRD. pykF, pykA, pfkA, and pfkB deletion mutants produced less acetate (9.44 ± 0.83, 3.86 ± 0.88, 0.30 ± 0.25, and 6.99 ± 0.85 g/l, respectively) than wild-type THRD cultures (19.75 ± 0.93 g/l). THRDΔpykF and THRDΔpykA produced 11.05 and 5.35 % more L-threonine, and achieved a 10.91 and 5.60 % higher yield on glucose, respectively. While THRDΔpfkA grew more slowly and produced less L-threonine than THRD, THRDΔpfkB produced levels of L-threonine (102.28 ± 2.80 g/l) and a yield on glucose (0.34 g/g) similar to that of THRD. The dual deletion mutant THRDΔpfkBΔpykF also achieved low acetate (7.42 ± 0.81 g/l) and high L-threonine yields (111.37 ± 2.71 g/l). The level of NADPH in THRDΔpfkA cultures was depressed, whereas all other mutants produced more NADPH than THRD did. These results demonstrated that modification of glycolysis in E. coli THRD reduced acetate production and increased accumulation of L-threonine.

Effects of dietary L-threonine and &lt;i&gt;Saccharomyces cerevisiae&lt;/i&gt; on performance, intestinal morphology and immune response of broiler chickens

The objective of this study was to investigate the effects of four dietary levels of L-threonine (0, 2.5, 5 and 7.5 g/kg) with or without Saccharomyces cerevisiae (SC) on performance, carcass characteristics, intestinal morphology and immune system of broiler chickens. A total of 360 1-d-old male broiler chicks were randomly allocated to eight treatments with three replicates of 15 birds. The experiment was done at 0 to 3 weeks (as starter phase) and 3 to 6 weeks (as grower phase). Growth performance traits including weight gain, feed intake and feed conversion ratio were recorded at the end of each week. At the end of the experiment eight birds per treatment were killed and carcass analysis was done. Sampling for blood evaluation was done on 7, 28 and 42 days of age. Results of this study indicated that use of SC did not affect feed intake, weight gain and feed conversion ratio in chicks in contrast with the L-threonine. Use of L-threonine improved feed conversion ratio and gain of birds. Carcass traits were not influenced by dietary L-threonine and SC supplements. Use of L-threonine increased the intestinal morphology parameters such as crypt depth and villi height and width in both jejunum and ileum segments. On the other hand, villi height and width and crypt depth increased in both jejunum and ileum segments when dietary L-threonine increased. Effect of SC supplement on intestinal morphology was not significant. Results of CBC (cell blood counts) parameters, such as white blood cells, red blood cells, haematocrit and haemoglobin showed that these parameters were not affected by dietary treatments. Furthermore, the immune response (antibody titre) against Newcastle disease was not affected by SC on both 26 and 42 days of age. However, use of L-threonine influenced the chicks’ immune response at 42 days of age. Our results have shown that the supplementation of L-threonine as a source of dietary-threonine in combination with SC improved growth performance and intestinal morphology traits in broilers.

Effect of l-Threonine Concentrations on Acetaldehyde Production and glyA Gene Expression in Fermented Milk by Streptococcus thermophilus

Serine hydroxymethyltransferase encoded by the glyA gene, which has been reported to possess threonine aldolase activity, is able to catalyze the conversion of L-threonine to glycine and acetaldehyde. In this study, eight strains of Streptococcus thermophilus strains with good flavor-enhancing property were investigated to evaluate the acetaldehyde production as well as the expression of glyA gene. S. thermophilus strain MGD4–7, with high levels of acetaldehyde production, was selected for the determination of acetaldehyde and for the analysis of glyA gene using quantitative real-time polymerase chain reaction in the presence and absence of L-threonine. The results indicated that the increased acetaldehyde production was linear with increasing L-threonine levels in the fermented milk. Further more, quantitative real-time PCR analysis showed that the glyA gene was upregulated in the fermented milk in the presence of L-threonine. Understanding the degradation pathway from threonine to glycine and acetaldehyde can be applied to control and improve acetaldehyde production in fermented products with S. thermophilus as the starter culture.

Níveis de treonina digestível para codorna japonesa na fase de produção

Avaliou-se a exigência de treonina digestível para a codorna japonesa em postura. Foram utilizadas 400 codornas, durante 63 dias. Utilizou-se delineamento inteiramente ao acaso, com cinco tratamentos, oito repetições e 10 aves por unidade experimental. A dieta basal foi deficiente em treonina, contendo 17,8% de proteína bruta, 2.900kcal de EM/kg, sendo suplementada com quatro níveis de L- treonina 98% (0,000; 0,052; 0,104; 0,156 e 0,208%), correspondendo à relação treonina digestível:lisina digestível de 0,55; 0,60; 0,65; 0,70 e 0,75, respectivamente. Os parâmetros estudados foram: consumo de ração, consumo de treonina, produção de ovo, peso do ovo, massa de ovos, conversão alimentar por massa de ovos, conversão alimentar por dúzia de ovos, componentes dos ovos (gema, albúmen e casca) e gravidade específica. Observou-se aumento linear (P&lt;0,01) somente para o consumo de treonina. Conclui-se que, para proporcionar os melhores resultados de desempenho e qualidade de ovos, a codorna japonesa exige 0,55% de treonina digestível, para um consumo diário de 144,61mg de treonina digestível/ave, correspondendo à relação treonina digestível: lisina digestível de 0,55.

Responses of Performance and Differential Leukocyte Count to Methionine and Threonine Supplementations on Broiler Chickens Challenged with Infectious Bursal Disease in Tropical Condition

The aim of this study was to find the effect of methionine and threonine supplementations higher than the NRC recommendation on growth performance and white blood cell differentiation of broiler chickens challenged with infectious bursal disease. A total of 450 day-old male broiler chicks were assigned to nine groups. Chickens were fed by three graded levels of DL- methionine [NRC (M1), 2 times NRC (M2) and 3 times NRC (M3)] and three graded levels of L-threonine [NRC (T1), 2 times NRC (T2) and 3 times NRC (T3)] from day 1-42 of age. On day 28, all birds were challenged with a commercial live-IBDV vaccine. Body Weight Gain (BWG) and Feed Intake (FI) and Feed Conversion Ratio (FCR) were significantly influenced by the dietary treatments before challenge and either methionine or threonine at the highest levels significantly decreased BWG, FI and FCR in broiler chickens. Birds were fed with M3T3 had the lowest body weight gain after challenge. Supplementation of two times methionine and threonine (M2T2) to the diet decreased peripheral blood heterophils and increased lymphocytes and H/L ratio on day 28. On day 42, complete white blood cell tended to increase with increasing level of methionine supplementation. Threonine did not affect peripheral blood differential leukocyte count of broiler chickens. In conclusion, our data suggest that the methionine and threonine requirement of male broiler chicks is higher for growth performance than was suggested by the last NRC committee and methionine and threonine higher than NRC requirements in tropical condition can ameliorate the negative effects of heat stress.

Change in Growth Performance and Liver Function Enzymes of Broiler Chickens Challenged with Infectious Bursal Disease Virus to Dietary Supplementation of Methionine and Threonine

Problem statement: The aim of this study was to verify the effects of methionine and threonine supplementations higher than the NRC recommendation on growth performance, liver function enzymes, blood parameters and immune tissues of broiler chickens challenged with infectious bursal disease. Approach: A total of 450 day-old male broiler chicks were as signed to nine groups. Chickens were fed by three graded levels of DL-methionine (NRC (M1), 2 times NRC (M2) and 3 times NRC (M3)) and three graded levels of L-threonine (NRC (T1), 2 times NRC (T2) and 3 times NRC (T3)) from day 1-42 of age. On day 28, all bird s were challenged with a commercial live-IBDV vaccine. Results: Body Weight Gain (BWG) and Feed Intake (FI) and Feed Conversion Ratio (FCR) were significantly influenced by the dietary treatm ents in starter phase and either methionine or threonine at the highest levels significantly decre ased BWG, FI and FCR in broiler chickens. A similar trend by methionine and threonine at the highest le vels was noted on BWG and FI in grower phase. The highest level of threonine significantly increa sed spleen weight on day 28 (pre-challenge) and 14 days post challenge. At 14 days after challenge, di etary supplementation of methionine at NRC recommended level (M1) significantly increased the serum concentrations of Alanine Aminotransferase (ALT), aspartate Aminotransferase (AST) and Lactate Dehydrogenase (LDH). In the T3 group, the serum concentrations of AST and LDH were significantly decreased, whereas the serum uric acid concentration was significantly increased . Conclusion/Recommendations: In conclusion, our data suggest that the methionin e and threonine requirement of male broiler chicks is higher for growth performance than was suggested by the last NRC committee and liver function enzymes results showed that methionine and threonine supplementation three times higher than NRC requirements in broiler chickens has not toxic pote ntial.

Quantitative dietary threonine requirement of juvenile Pacific white shrimp,Litopenaeus vannamei(Boone) reared in low-salinity water

An 8-week feeding trial was conducted to determine the threonine requirement of juvenile Pacific white shrimp Litopenaeus vannamei (Boone) in low-salinity water (0.50–1.50 g L−1). Diets 1–6 were formulated to contain 360 g kg−1 crude protein with fish meal, wheat gluten and pre-coated crystalline amino acids with six graded levels of l-threonine (9.9–19.0 g kg−1 dry diet). Diet 7, which was served as a reference, contained only intact proteins (fish meal and wheat gluten). Each diet was randomly assigned to triplicate groups of 30 shrimps (0.48±0.01 g), each four times daily. Shrimps fed the reference diet had similar growth performance and feed utilization efficiency compared with shrimps fed the diets containing 13.3 g kg−1 or higher threonine. Maximum specific growth rate (SGR) and protein efficiency ratio were obtained at 14.6 g kg−1 dietary threonine, and increasing threonine beyond this level did not result in a better performance. Body compositions, triacyglycerol and total protein concentrations in haemolymph were significantly affected by the threonine level; however, the threonine contents in muscle, aspartate aminotransferase and alanine aminotransferase activities in haemolymph were not influenced by the dietary threonine levels. Broken-line regression analysis on SGR indicated that optimal dietary threonine requirement for L. vannamei was 13.6 g kg−1 dry diet (37.8 g kg−1 dietary protein).

Níveis de treonina digestível em dietas para codorna japonesa em postura

O experimento foi conduzido para estimar o nível de treonina digestível para codornas japonesas em postura, durante 63 dias. Quatrocentas codornas, com idade inicial de 57 dias, foram distribuídas em delineamento inteiramente casualizado com cinco tratamentos, oito repetições e 10 aves por unidade experimental. A dieta basal, deficiente em treonina e com 20% PB, 2.910 kcal EM/kg, foi suplementada com cinco níveis de L-treonina 98% (0,018; 0,074; 0,128; 0,183 e 0,239%), correspondendo à relação treonina digestível:lisina digestível de 0,65; 0,70; 0,75; 0,80 e 0,85, respectivamente, para compor os tratamentos experimentais. As características estudadas foram: consumo de ração, consumo de treonina, produção de ovos, produção de ovos comercializáveis, peso do ovo, massa de ovos, conversão alimentar por massa de ovos, conversão alimentar por dúzia de ovos, qualidade dos ovos (gema, albúmen e casca), altura e diâmetro dos ovos e gravidade específica. Observou-se efeito linear dos tratamentos somente sobre o consumo de treonina. Concluiu-se que, para proporcionar os melhores resultados de desempenho e de qualidade de ovos, a codorna japonesa não exige mais que 0,65% de treonina digestível para um consumo de 149,2 mg de treonina digestível/dia ou um consumo diário de 14,34 mg de treonina digestível/g ovo, correspondendo à relação treonina digestível:lisina digestível de 0,65.

Dietary amino acid l-threonine requirement of fingerling Indian catfish, Heteropneustes fossilis (Bloch) estimated by growth and biochemical parameters

An eight-week feeding experiment was conducted to quantify the dietary threonine requirement of young catfish, Heteropneustes fossilis (9.20 ± 0.85 cm, 3.60 ± 0.45 g) using isonitrogenous and isoenergetic diets [40% crude protein (CP); 4.28 kcal g/100 g, gross energy (GE)] containing casein, gelatin and l-crystalline amino acids. Six dietary treatments supplemented with graded levels of l-threonine (0.50, 0.75, 1.00, 1.25, 1.50 and 1.75 g per 100 g, dry diet), in gradations of 0.25 g per 100 g dry diet were formulated. Fish were randomly stocked, in triplicate groups, in 55-l indoor polyvinyl flow-through circular tanks and fed experimental diets at 4% of their body weight divided over two equal feedings at 08:00 and 16:00 hours. Feeding schedule and ration size were worked out prior to the start of the feeding trial. Live weight gain (263%), feed conversion ratio (FCR) (1.35) and protein efficiency ratio (PER) (1.85) were significantly higher (P < 0.05) in fish fed a diet containing 1.25% dietary threonine. However, second-degree polynomial regression analysis of live weight gain, FCR, PER and body protein deposition data indicated the dietary threonine requirement to be 1.37, 1.26, 1.23 and 1.24 g per 100 g of dry diet, respectively. Whole-body moisture decreased significantly (P < 0.05) with the increase of dietary concentration up to 1.25%. A significantly (P < 0.05) higher protein content was evident in fish fed a diet containing 1.25% threonine. Body fat increased significantly (P < 0.05) with the increase of dietary concentration and was found to be highest at a 1.75% threonine concentration. A significantly (P < 0.05) higher ash content was reported at the 0.50 and 0.75% threonine levels. Body protein deposition was also found to be significantly (P < 0.05) higher at the 1.25% threonine level, followed by the 1.50% threonine level. Based on these results, it is recommended that the diet for fingerling H. fossilis should contain threonine at a level of 1.27 g per 100 g of dry diet, corresponding to 3.17 g per 100 g of dietary protein for optimum growth and efficient feed utilization. No mortality was observed during the experiment.

Maintenance threonine requirement and efficiency of its use for accretion of whole-body threonine and protein in Atlantic salmon (Salmo salar L.) fry

Eighteen groups of seventy Atlantic salmon (Salmo salar L.) fry (initial mean body weight 0.8 (sd 0.01) g) were fed on semi-purified diets containing graded levels of l-threonine (Thr) in 15 litres aquaria at a temperature of 14.5+/-1 degrees C. Doses of Thr represented 1, 31, 41, 51, 62, 72, 83 and 93 % of its ideal level for optimum protein deposition. Indispensable amino acids other than Thr were included in the same proportion (on a g/16 g N basis) as in the Atlantic salmon fry whole-body carcass. Following 36 d of feeding and a 36 h fast, fry were killed for whole-body protein and amino acid analysis. Weight gain (r2 0.98), protein accretion (r2 0.97), and Thr accretion (r2 0.97) were linear (P<0.01) functions of Thr intake. Slope of the Thr accretion regression line showed that the efficiency of Thr utilisation above maintenance was 76 %. At zero Thr intake, fry lost 5.4 mg Thr/kg body weight0.75 per d. The Thr maintenance requirement was 7.2 mg/kg body weight0.75 per d and the Thr requirement for growth was 66 mg for 1 g protein deposition. Increasing doses of Thr resulted in increased (P<0.05) concentrations of histidine and lysine, and decreased concentrations of isoleucine in whole-body protein. The maintenance need for Thr represented 13.4 % of the total need for Thr. The data suggest that efficiency of Thr utilisation above maintenance is constant at all levels of Thr intake between 1 and 93 % of the level required for optimum protein deposition.