Dietary Methionine Concentrations Research Articles

Exploring the physiological plasticity of giant grouper (Epinephelus lanceolatus) to dietary sulfur amino acids and taurine to measure dietary requirements and essentiality.

Giant grouper (Epinephelus lanceolatus) is an economically important yet under-researched species, still reliant on 'trash fish' or generic aquafeeds. The transition toward sustainable formulations is contingent on establishing requirements of target species for limiting nutrients, among which the sulfur amino acids (methionine and cysteine) commonly limit fish growth. Further, there remains significant conjecture around the role of the sulfonic acid taurine in marine aquafeed formulation and its relationship to sulfur amino acids. To develop a species-specific feed formulation for giant grouper, dietary methionine was modulated in a dose-response experiment to achieve five graded levels from 9.5 to 21.5 g/kg, including an additional diet with methionine at 18.6 g/kg supplemented with 8 g/kg taurine. The mean (±SD) cysteine level of the diets was 4.5 ± 0.3 g/kg. Each diet was randomly allocated to triplicate tanks of 14 fish (83.9 ± 8.4 g). The best-fit regression for growth showed that the optimal dietary methionine content was 15.8 g/kg and the total sulfur amino acid content was 20.3 g/kg. Inadequate dietary methionine content triggered physiological responses, including hepatic hyperplasia and hypoplasia at 9.5 and 21.5 g/kg, respectively, and high aspartate transaminase levels at 18.9 g/kg. Moreover, inadequate dietary methionine contents resulted in higher densities of mixed goblet cell mucin and reduced absorptive surface area of posterior intestinal villi. Our results suggest that adequate levels of methionine, but not taurine, improved posterior intestinal conditions and liver homeostasis. These findings may aid informulating aquafeeds to optimize gastrointestinal and liver functions in juvenile giant grouper.

Elevated sea temperature combined with dietary methionine levels affect feed intake and appetite-related neuropeptide expression in the brains of juvenile cobia (Rachycentron canadum)

This study aimed to determine the impact of elevated temperature combined with different levels of dietary methionine concentrations on feed intake (FI) and brain expression of selected neuropeptides and one receptor involved in appetite control in juvenile cobia (approximately 3.7 g body weight). The genes studies were neuropeptide y, npy; agouti-related protein, agrp; cocaine- and amphetamine-regulated transcript, cart; cholecystokinin, cck and melanocortin 4 receptor; mc4r. The cobia were reared at typical sea water temperature in Vietnam (30 °C) and elevated temperature (34°C; selected as one of the predicted scenarios of climate change). The fish were fed diets with different levels of methionine: deficient (M9; 9.1 g/kg), sufficient (M12; 12.8 g/kg) and surplus (M16, 16.8 g/kg) for 6 weeks (triplicate tanks per treatment). Both dietary methionine concentration and temperature affected FI in cobia. Dietary methionine deficiency (i.e., M9) and elevated temperature reduced FI in cobia. Temperature significantly influenced the mRNA expression of agrp, cart, cck and mc4r. Expression of the orexigenic neuropeptide npy was consistently higher before the meal than after the meal for all diets and at both temperatures. At 30°C, prefeeding levels of npy correlated with both increased methionine levels and FI. The interaction between dietary methionine and temperature on the levels of brain npy expression was significant (P<0.05). There was higher brain expression of agrp, cart and cck in cobia at 34°C than in fish at 30°C, which was correlated with a lower FI. In conclusion, both feeding, temperature and/or dietary methionine levels affected the brain expression of npy and agrp, cart, cck and mc4r. This suggests that these neuropeptides as well as the mc4r receptor are actively involved in adjusting feed intake to compensate for changing energetic demands, as well as metabolic adjustments due to the variable availability of methionine at elevated temperature.

Response of Rainbow Trout (Oncorhynchus mykiss) Growing from 50 to 150 g to Supplements of DL-Methionine in a Semipurified Diet Containing Low or High Levels of Cystine

We studied the effect of increasing dietary concentrations of DL-methionine on growth, feed intake, feed conversion ratio and the composition of gain in rainbow trout. Twenty-four groups of 20 trout initially weighing 51 ± 0.5 g/trout were fed semipurified diets containing 20.1 MJ digestible energy and either 3.0 or 5.8 g cystine/kg dry matter. At each level of cystine, 12 levels of methionine (2 to 11 g/kg dry matter) were achieved by supplementation with graded quantities of DL-methionine. During an experiment of 49 feeding days, no significant effect of the level of dietary cystine was found for any performance trait. Nonlinear responses to increasing dietary methionine concentrations were found for feed intake, growth rate, protein concentration of gain and protein deposition, whereas fat concentration of gain decreased concurrently. Dietary methionine was utilized most efficiently at a concentration of 3.5 g methionine/kg dry matter or 0.17 g/MJ digestible energy. Ninety-five percent of the plateau deposition of body protein was achieved at a dietary methionine concentration of 8 g/kg dry matter or 0.40 g/MJ digestible energy. For achieving 98%, the required concentration was 9.0 g/kg or 0.49 g/MJ. Recommended dietary methionine concentration will depend on the trait chosen.

Nonobese mice with nonalcoholic steatohepatitis fed on a choline-deficient, l-amino acid-defined, high-fat diet exhibit alterations in signaling pathways.

Nonalcoholic steatohepatitis (NASH) is often associated with obesity, but some patients develop NASH without obesity. The physiological processes by which nonobese patients develop NASH and cirrhosis have not yet been determined. Here, we analyzed the effects of dietary methionine content on NASH induced in mice fed on a choline‐deficient, methionine‐lowered, l‐amino acid‐defined high‐fat diet (CDAHFD). CDAHFD with insufficient methionine induced insulin sensitivity and enhanced NASH pathology, but without obesity. In contrast, CDAHFD with sufficient methionine induced steatosis, and unlike CDAHFD with insufficient methionine, also induced obesity and insulin resistance. Gene profile analysis revealed that the disease severity in CDAHFD may partially be due to upregulation of the Rho family GTPases pathway and mitochondrial and nuclear receptor signal dysfunction. The signaling factors/pathways detected in this study may assist in future study of NASH regulation, especially its ‘nonobese’ subtype.

A study on methionine-mediated regulation of muscle fiber growth, development and differentiation in the rice field eel (Monopterus albus)

An eight-week feeding trial was performed to determine how methionine regulates muscle growth in the rice field eel Monopterus albus (initial weight 25.08 ± 0.31 g). Six isonitrogenous and isoenergetic experimental feeds were formulated, and different levels of methionine (0, 2 g/kg, 4 g/kg, 6 g/kg, 8 g/kg, or 10 g/kg) were added to the basic diet (110 g/kg fish meal, 400 g/kg soy concentrate meal). The weight gain rate (WGR) of M. albus markedly increased as methionine concentrations increased to 6 g/kg (P < 0.05) and gradually decreased as methionine concentrations increased to 10 g/kg. The feed conversion rate of M. albus showed a trend opposite to the WGR. Muscle glycogen markedly increased as methionine concentrations increased to 2 g/kg (P < 0.05), while the creatine kinase, lactic acid and lactate dehydrogenase contents of muscle markedly decreased as dietary methionine concentrations increased to 2 g/kg (P < 0.05). The content of amino acids, total essential amino acids, total nonessential amino acids and total amino acids in muscle was increased by supplementation with 8 g/kg and 10 g/kg methionine. The springiness of muscle markedly increased as methionine supplementation increased to concentrations of 6 g/kg (P < 0.05). The hardness, gumminess and chewiness of muscle markedly increased as methionine concentrations increased to 8 g/kg (P < 0.05). When supplemented with 8 g/kg and 10 g/kg methionine, the density of muscle fibers and the percentage of muscle fibers under 60 μm were remarkably decreased, while the percentage of muscle fibers greater than or equal to 100 μm was remarkably increased (P < 0.05). When 8 g/kg and 10 g/kg methionine were added, gcn2 and mstn mRNA expression was significantly downregulated (P < 0.05), while gh, ghr, TnT, mhc, mlc, myf5, myod2, myog, pax7 and mef2a mRNA expression was remarkably upregulated (P < 0.05). Correlative analysis of muscle-related gene expression showed that myf5, mlc, and myog expression was negatively correlated with gcn2 expression (P < 0.05), and ghr, mef2b, gh, and mhc expression was negatively correlated with gcn2 expression (P < 0.01), while mstn expression was positively correlated with gcn2 expression (P < 0.01). In conclusion, dietary methionine increased the growth performance of M. albus, especially for muscle growth and development, improved muscle texture and main nutritional factors (amino acids, glycogen), and reduced the content of lactic acid in muscle.

Dietary methionine spares the requirement for taurine in juvenile Yellowtail Kingfish (Seriola lalandi)

Taurine, a β-sulphonic amino acid, is a growth and health promoting dietary supplement in commercial finfish aquaculture. Reported recommendations for taurine supplementation in Seriola spp. feeds broadly range from 2.6 to 10.2 g kg−1 diet. Methionine is an essential amino acid and substrate for various metabolic compounds and acts as a methyl and sulfur donor, potentially sparing taurine. Dietary methionine requirements are currently unknown for Yellowtail Kingfish (Seriola lalandi); however, recommendations for the closely related Japanese Yellowtail (Seriola quinqueradiata) indicate that 11.1 g kg−1 diet is adequate. The taurine requirement and sparing effect of methionine of juvenile Yellowtail Kingfish was quantified by conducting a feeding experiment and applying a factorial, orthogonal dose-response design. Fourteen isonitrogenous and isoenergetic diets were prepared using practical raw ingredients with either one of two levels of methionine (10.9 ± 0.2 g kg−1 or 17.2 ± 0.6 g kg−1) and either one of seven levels of taurine, increasing from 1.6 to 20.4 g kg−1, respectively. Triplicate groups of 14 fish (53.3 ± 0.4 g fish−1) were fed one of the 14 diets over seven weeks. Based on growth and feeding results, juvenile Yellowtail Kingfish do not require dietary taurine supplementations when the basal taurine diets content is at least 1.6 g taurine kg−1 at a dietary methionine content of 17.2 ± 0.6 g kg−1 diet. This demonstrates that dietary methionine has a sparing effect on taurine supplementation. Yellowtail Kingfish fed dietary methionine exceeding the current minimum industry standard (~11.1 g kg−1), grew more rapidly than those fed high dietary taurine contents at dietary methionine levels approximating that of current industry practice, indicating the indispensability of adequate methionine supply. Breakpoint analysis on the specific growth rate in Yellowtail Kingfish fed a methionine level of current industry practice, estimated a digestible taurine requirement of 1.98 g kgBW−1 d−1 at an average digestible methionine intake of 3.4 g kgBW−1 d−1 This equates to a dietary taurine content of 7.7 g kg−1 diet at a dietary methionine content of 10.9 g kg−1 diet. Our results indicate that in juvenile Yellowtail Kingfish: adequate dietary methionine spares dietary taurine supplementation; insufficient dietary methionine provokes a taurine requirement; and current industry specifications for dietary methionine for Yellowtail Kingfish aquafeed require reassessment.

Effect of Sows Gestational Methionine/Lysine Ratio on Maternal and Placental Hydrogen Sulfide Production.

Simple SummaryHydrogen sulfide (H2S) is an important second messenger, which has been implicated in regulating placental angiogenesis. Our findings revealed that gestational dietary methionine could affect maternal and placental H2S concentrations. With the increase of dietary methionine, maternal plasma and placental H2S concentrations changed quadratically, which was consistent with placental vascular density and reproductive performance. The decrease in H2S production caused by an increase in dietary methionine was likely to be the cause for the increase in the rate of low birth weight piglets and needs further study.The placenta is a unique bond between the mother and the fetus during pregnancy, and a proper placental angiogenesis is vital for fetal development. H2S is an endogenous stimulator of angiogenesis that is mainly produced by the methionine transsulfurationpathway. The goal of this study was to evaluate the effect of gestational dietary methionine on maternal and placental H2S production in sows. Multiparous sows (Large×White; third parity; n = 65) were randomly allocated into five groups, with feed diets comprisingstandardized ileal digestible methionine/lysine (Met/Lys) ratios of 0.27 (nutrient requirements of swine (NRC); 2012 level), 0.32, 0.37, 0.42, and 0.47, respectively. The litter size and weight at birth were measured and recorded. Maternal blood samples were obtained at embryonic day (E) E40 d, E90 d, and E114 d of gestation. The placental samples were collected at parturition. The results showed that maternal plasma H2S concentration was not affected at E40 d. However, the maternal plasma H2S concentration changed quadratically with the dietary Met/Lys ratio at E90 d (p < 0.01) and E114 d (p = 0.03). The maximum maternal plasma H2S concentration was at the dietary Met/Lys ratio of 0.37. Meanwhile, maternal plasma H2S concentration was positively correlated with piglets born alive (p < 0.01) and litter weight (p < 0.01). Consistent with the maternal plasma, the placental H2S concentration also changed quadratically with the dietary Met/Lys ratio (p = 0.03); the Met/Lys ratio of 0.37 showed the maximum H2S concentration. In conclusion, our findings revealed that the gestational dietary Met/Lys ratio could affect maternal and placental H2S concentrations, which may be an important molecular mechanism affecting placental angiogenesis and piglet development.

The effect of dietary methionine levels on growth, feed conversion and protein retention efficiency of Nile Tilapia (Oreochromis niloticus) fingerlings

Abstract. Mohammed FA, Yousif RA, Hilal FM, Adam RA, Ahmed TK. 2020. The effect of dietary methionine levels on growth, feed conversion and protein retention efficiency of Nile Tilapia (Oreochromis niloticus) fingerlings. Nusantara Bioscience 12: 21-27. A 49 days feeding trial was conducted to evaluate growth, feed utilization and body composition of Nile tilapia Oreochromis niloticus (4.30±0.01 g), fed five isonitrogenous (32 g 100 g-1 crude protein) and isoenergetic (14.51 kJ g-1 Gross energy) practical diets and five levels of methionine supplementation (0.5, 1, 1.5, 2 and 2.5 g 100 g-1). The experimental design was completely randomized with five treatments and three replicates. Fish were stocked in triplicate groups of 20 fish held in 70 L flow-through tanks (water volume 55 L) and fed twice daily (08:00 am and 04:30 pm) to apparent satiation. When absolute weight gain (AWG; g fish-1), feed conversion ratio, protein deposition (g fish-1) and protein retention efficiency (%) data were subjected to second-degree polynomial regression analysis 95% of the plateau of the above parameters was achieved at dietary methionine concentrations between 1.4-1.5 g 100 g-1 dry diet or 0.09-0.10 g methionine kJ-1 GE. Corresponding to 4.4-4.7 g 100 g-1 of the dietary protein. Based on these results, dietary methionine requirement for Nile tilapia Oreochromis niloticus is recommended 1.4-1.5 g 100 g-1 diet.

The role of dietary methionine concentrations on growth, metabolism and N-retention in cobia (Rachycentron canadum) at elevated water temperatures.

This study determined impacts of dietary methionine concentrations at two temperatures on growth, feeding efficiency and N‐metabolites in juvenile cobia. Methionine concentrations of the experimental diets were deficient (M9; 9 g/kg), sufficient (M12; 12 g/kg) and surplus (M16, 16 g/kg). Water temperature was normal (30°C) or elevated (34°C). Twenty cobia in triplicate tanks were fed the experimental diets for 6 weeks. Both methionine and temperature affected cobia's growth and feeding efficiency. Cobia fed M9 performed lower than the fish fed M12 and M16 diets. Additionally, cobia reared at 34°C performed poorer than at 30°C, probably due to lower voluntary feed intake in the fish reared at 34°C. Protein efficiency ratio and protein productive value in cobia fed M9 diet were less than M12 or M16 diets. This was confirmed with the improved retentions of indispensable amino acids (AAs). No interactions between methionine and temperature were observed in growth and protein accretion. At 30°C, CF improved, while HSI and VSI declined upon methionine supplementation levels. Of which an interaction between temperature and methionine was present. Plasma, muscle and liver free AA and N‐metabolites were affected by methionine and temperature. Furthermore, temperature affected cobia's lipid class composition, resulting in increased phospholipids and cholesterol at 34°C.

Influence of Dietary Copper Methionine Concentrations on Growth Performance, Digestibility of Nutrients, Serum Lipid Profiles, and Immune Defenses in Broilers.

A 42-day experiment was conducted to evaluate the influence of dietary copper (Cu) concentrations on growth performance, nutrient digestibility, and serum parameters in broilers aged from 1 to 42days. Five hundred forty 1-day-old broilers were randomly assigned into 1 of the following 6 dietary treatments: (1) control (basal diet without supplemental Cu), (2) 15mg/kg supplemental Cu (Cu15), (3) 30mg/kg supplemental Cu (Cu30), (4) 60mg/kg supplemental Cu (Cu60), (5) 120mg/kg supplemental Cu (Cu120), and (6) 240mg/kg supplemental Cu (Cu240), Cu as copper methionine. A 4-day metabolism trial was conducted during the last week of the experiment feeding. The results showed that dietary Cu supplementation increased the average daily gain and the average daily feed intake (P < 0.01). The feed gain ratio, however, was not affected by dietary Cu (P > 0.10). Additionally, dietary Cu supplementation increased the digestibility of fat and energy (P < 0.05). The concentration of serum cholesterol, triglycerides, and high-density lipoprotein cholesterol decreased with dietary Cu supplementation (P < 0.05). The activities of serum Cu-Zn superoxide dismutase (P < 0.05), glutathione peroxidase (P < 0.05), and ceruloplasmin (P = 0.09), on the contrary, were increased by Cu addition. For immune indexes, dietary Cu supplementation increased serum IgA and IgM (P < 0.05). In addition, the activities of serum ALT increased with increasing dietary Cu supplementation (P < 0.05). In conclusion, our data suggest that Cu supplementation can increase fat digestibility and promote growth. Additionally, dietary Cu supplementation can reduce serum cholesterol and enhance antioxidant capacity in broilers.

Tissue and plasma antioxidant status in response to dietary methionine concentration and source in broilers.

This study hypothesized that plasma and tissue antioxidant status of broilers is positively influenced when dietary Met concentrations exceed, and negatively when they go below NRC recommendations. In addition, different Met sources are hypothesized to affect the antioxidant defence system differently. Day-old male Cobb-500 broilers (n=336) were allotted to seven groups and phase-fed three wheat-soya bean meal-based basal diets during days 1-10, 11-21 and 22-35. The basal diets (Met- group, Met+Cys concentration 15% below NRC recommendations) were supplemented with 0.10%, 0.25% or 0.40% Met either as DL-Met (DLM) or DL-2-hydroxy-4-(methylthio) butanoic acid (DL-HMTBA) (equimolar comparison). Growth performance and carcass weights were lower in the Met- group compared to the groups whose diets met or exceeded Met requirements. The antioxidant defence system was not influenced by the Met source. However, in the liver, concentrations of glutathione increased with increasing dietary Met concentrations. Tocopherol concentrations in the liver at days 10 and 21 were lower in the Met- group than in the groups supplemented with Met. However, liver concentrations of thiobarbituric acid reactive substances (TBA-RS) and protein carbonyls (PC) were largely not influenced by dietary Met concentration. Plasma tocopherol concentrations at day 35 were lower, and those of TBA-RS and PC at day 35 were higher in Met- group than in the groups fed the Met-supplemented diets. In jejunum, but not in liver, relative mRNA abundances and activities of superoxide dismutase, catalase and glutathione peroxidase were higher in the Met- group than in the groups fed Met-supplemented diets. These data indicate that suboptimum supply of Met results in decreased antioxidant concentrations in plasma and body tissues, and increases oxidative stress in the jejunum mucosa. However, supplementation of Met in excess of the requirements (based on NRC) compared to diets adequate in Met+Cys did not influence the antioxidant defence system.

Effect of dietary methionine level on muscle growth mechanisms in juvenile rainbow trout (Oncorhynchus mykiss)

The aim of the study was to analyse the effects of different dietary methionine (Met) concentrations on the mechanisms of fish muscle growth (hyperplasia and hypertrophy) by using cellular and molecular approaches. Three plant-based diets differing by their Met level (MD, Met-deficient; MC, Met-control, corresponding to established Met requirement; MH, Met-high) were fed to rainbow trout juveniles for 12weeks. Met deficiency led to a reduced somatic growth right from the first 3weeks of feeding onwards, while feeding the MH-diet led to an increased body growth in the 6 last weeks of feeding. The protein gain of the juveniles increased with dietary Met content. The protein retention efficiency of the MD-fed juveniles was half that of the MC- and MH-fed juveniles which were statistically similar. The changes induced by MD- and MH-feeding at muscle molecular and cellular levels were different. Compared to control, dietary Met deficiency altered the expression of myogenic, muscle growth- and metabolism-related genes by increasing Myf5, MyoD1, Mrf4, Mef2a, βact, CathD, GSTπ and TNFα expressions and decreasing Col1α1 and IGF1 expressions, whereas a high level of dietary Met decreased Pax7a2, Mef2c, βact, CathD, GDH2 and NF-κB expressions. The Met-control fed fish were discrimated according to HGF, Pax7a1 and Pax7a2 expressions. Dietary Met level thus acted on the expression of genes regulating specific transition points of myogenesis, and affected the expression of muscle structural genes and growth factors involved in satellite cell activation and muscle growth. Molecular results suggested that MD-diet favours satellite cell return to quiescence, while MC-diet favours satellite cell activation and MH-diet myogenic differentiation. At cellular level, the muscle total cross-sectional area of the juveniles fed the MD-diet was 28% lower than that of the juveniles fed the MC-diet despite a similar total number of white muscle fibres, and the number of white muscle fibres with a large diameter was lower in MD-fed fish than in MC-fed ones. The muscle total cross-sectional area of the juveniles fed the MH-diet was 32% higher than that of the juveniles fed the MC-diet, their total number of white muscle fibres 25% higher, and their number of white muscle fibres with a large diameter similar. Increasing dietary methionine above established requirement thus promotes white muscle hyperplasia and muscle growth in rainbow trout juveniles, while methionine deficiency dysregulates the expression of myogenic and muscle growth-related genes and impairs white fibre hypertrophy. Statement of relevanceDetermining the effects of dietary methionine levels on muscle growth mechanisms will help develop low fish meal feeds.

Antioxidant status and expression of inflammatory genes in gut and liver of piglets fed different dietary methionine concentrations.

This study investigated the hypothesis that dietary concentrations of methionine (Met), as a precursor of cysteine which is a constituent of glutathione (GSH), affect tissue antioxidant concentrations and the antioxidant defence system in pigs. Forty-five piglets (DanZucht×Pietrain) were allotted to three groups of similar mean body weight (11.0±0.9kg). The basal diet was composed of barley, wheat, corn starch, soybean oil, sucrose, cellulose and a mineral supplement with suboptimal concentrations of Met and was supplemented with dl-Met to reach 0.16%, 0.20% and 0.24% of dietary Met and 0.40%, 0.44% and 0.48% of dietary Met and cysteine in groups 0.16, 0.20 and 0.24 respectively. After 3weeks, at slaughter, samples of liver, jejunum mucosa and plasma were collected. Feed intake and weight gains increased and feed:gain ratio decreased when dietary Met concentrations increased. The Trolox equivalent antioxidant capacity (TEAC), concentrations of GSH and thiobarbituric acid reactive substances (TBA-RS) and the activity of the glutathione peroxidase (GPx) in liver and jejunum mucosa were similar in all groups (p>0.05). Relative mRNA concentrations of selected target genes of the nuclear factor (erythroid-derived 2)-like 2 (Nrf2), the master regulator of the antioxidant response, and of the nuclear factor 'kappa-light-chain-enhancer' of activated B-cells (NF-κB), the master regulator of inflammation, were largely unaffected both in jejunum and liver. In conclusion, inflammation- and oxidative stress-related pathways on the molecular level, and concentrations of lipid peroxidation products, of antioxidants and of enzymes involved in the antioxidant defence system were mostly unaffected by dietary Met concentration in gut and liver. These findings suggest that suboptimal dietary Met concentrations did not influence the antioxidant defence system of gut and liver in healthy piglets.

Response of growing goslings to dietary supplementation with methionine and betaine

An experiment with a 2 × 3 factorial design with two concentrations of dietary betaine (0 and 600 mg/kg) and three dietary concentrations of methionine (0, 600 and 1200 mg/kg) was conducted using goslings to estimate growth, nutrient utilisation and digestibility of amino acids from 21 to 70 d of age.Three hundred geese were randomised at 18 d of age into 6 groups with 5 replicates per treatment and 10 geese per replicate.Increasing dietary concentrations of methionine gave a linear increase in body weight and average daily gain. The coefficient of crude fat retention increased as dietary methionine increased and there was a significant non-linear response to increasing dietary methionine. Similarly, increasing supplemental methionine gave linear increases in the digestibility of methionine and cysteine.The results of this study indicated that optimal dietary supplementation of methionine could increase growth performance and methionine and cysteine utilisation in growing goslings. Betaine supplementation had no apparent sparing effect on methionine needs for growth performance, but did improve the apparent cysteine digestibility.

Efficacy of DL-methionine hydroxy analogue-free acid in comparison to DL-methionine in growing male white Pekin ducks

The present study was performed to assess the bioefficacy of DL-methionine hydroxy analogue-free acid (MHA) in comparison to DL-methionine (DLM) as sources of methionine for growing male white Pekin ducks in the first 3 wk of life. For this aim, 580 1-day-old male ducks were allocated into 12 treatment groups and received a basal diet that contained 0.29% of methionine, 0.34% of cysteine and 0.63% of total sulphur containing amino acids or the same diet supplemented with either DLM or MHA in amounts to supply 0.05, 0.10, 0.15, 0.20, and 0.25% of methionine equivalents. Ducks fed the control diet without methionine supplement had the lowest final body weights, daily body weight gains and feed intake among all groups. Supplementation of methionine improved final body weights and daily body weight gains in a dose dependent-manner. There was, however, no significant effect of the source of methionine on all of the performance responses. Evaluation of the data of daily body weight gains with an exponential model of regression revealed a nearly identical efficacy (slope of the curves) of both compounds for growth (DLM = 100%, MHA = 101%). According to the exponential model of regression, 95% of the maximum values of daily body weight gain were reached at methionine supplementary levels of 0.080% and 0.079% for DLM and MHA, respectively. Overall, the present study indicates that MHA and DLM have a similar efficacy as sources of methionine for growing ducks. It is moreover shown that dietary methionine concentrations of 0.37% are required to reach 95% of the maximum of daily body weight gains in ducks during the first 3 wk of life.

The effect of dietary methionine concentrations on growth performance of juvenile Nile tilapia (Oreochromis niloticus) fed diets with two different digestible energy levels

A growth trial was conducted to examine the effect of dietary digestible energy (DE) content on methionine (Met) utilization and requirement in juvenile Nile tilapia (Oreochromis niloticus). Ten iso-nitrogenous (288 g kg(-1) protein) practical diets, with two DE levels (10.9 MJ kg(-1); 12.4 MJ kg(-1)) and five methionine supplementation levels (0, 1, 2, 4 and 6 g kg(-1)), were hand-fed twice daily to triplicate groups of Nile tilapia (initial body weight 8.95 +/- 0.06 g) for 8 weeks. Weight gain (WG) and specific growth rate (SGR) increased significantly with increasing dietary methionine concentration at the same DE content (P < 0.001). At the same dietary methionine level, WG and SGR of fish fed high-DE diets were significantly higher than that of fish fed low-DE diets (P = 0.0001), although no interaction was found between dietary DE and methionine supplementation. Based on quadratic regression analysis between dietary methionine concentration and weight gain, optimal methionine requirement for maximum growth, expressed as g Met required kg(-1) diet (low-versus high-DE diets), increased as diet DE concentration increased (7.34 versus 9.90 g kg(-1) diet, respectively; with cysteine 4.70 g kg(-1) diet). The results indicated that diet DE content affects methionine utilization and requirement in juvenile Nile tilapia, fish fed high-DE diets required more methionine for maximum growth.

Effect of dietary methionine content on growth performance, carcass traits, and feather growth of Pekin duck from 15 to 35 days of age

A study was conducted to establish the response of Pekin ducks to dietary Met from 15 to 35 d age. Experimental diets were formulated to contain 0.35, 0.45, 0.55, 0.65, and 0.75% Met (0.30, 0.39, 0.45, 0.56, and 0.68% on an analyzed basis, respectively) and 0.3% cysteine (0.25, 0.27, 0.26, 0.26, and 0.28% on an analyzed basis, respectively). Each diet was fed to 10 pens of 55 ducks/pen. Carcass yields and feather growth were determined at 28 and 35 d. Results showed that feeding 0.30% Met (0.55% Met+Cys) significantly impaired ADG, feed-to-gain (F:G) ratio, breast meat yield, and feather growth in comparison to the other dietary treatments (P < 0.05). BW, ADG, F:G, carcass and breast meat weight and yield, breast skin and subcutaneous fat weight and yield, the fourth primary wing feather length, and feather coverage showed significant quadratic broken-line or quadratic polynomial response to increasing dietary Met (P < 0.05). From 15 to 28 d age, the optimal Met requirement for the BW, breast meat yield, and the fourth primary wing feather length were 0.510, 0.445, and 0.404%, respectively, based on quadratic broken-line model, and correspondingly were 0.606, 0.576, and 0.559% by quadratic regression. For ducks from 15 to 35 d age, the optimal Met requirement for BW, breast meat yield, and feather coverage were 0.468, 0.408, and 0.484%, respectively, by quadratic broken-line model, and 0.605, 0.564, and 0.612%, by quadratic regression, respectively.

Dietary methionine supplementation alters the expression of genes involved in methionine metabolism in salmonids

The objective of the present study was to investigate the effect of dietary methionine (Met) concentration and alternating feeding strategies in methionine delivery, on the mRNA transcript levels of genes involved in Met resynthesis (betaine-homocysteine methyltransferase, BHMT; S-adenosylhomocysteine hydrolase, SAHH) and net Met loss (taurine synthesis) (cystathionine beta-synthase, CBS) in Atlantic salmon (Salmo salar) liver. Salmon alevins (265 ± 3 mg) were distributed into 24 tanks (50 fish per tank; 3 replicates). The experimental diets were supplemented with l-methionine at 0, 1.9, 5.8, and 17.4 g/kg (M0, M1/3, M1, and M3, respectively). The M3 diet without glycine was prepared to examine Met toxicity (M3-G). These diets were provided via “mono-feeding strategy,” meaning fish were fed a designated single diet. This experiment also included alternative feeding groups with “duo-feeding” strategy: AF1 (fish fed M0 for 2 days followed by M1 for 1 day), AF2 (fish fed M0 for 2 days followed by M3 for 1 day), and AF3 (fish fed two meals of M0 followed by one meal of M3). Salmon fed M0 diet had smaller weight compared to all other groups. There was no effect of alternative feeding on the growth except with the M0 group. The highest expression of CBS gene was found in the M0, M1/3, and AF-1 groups compared to the M3 and M3-G groups. The expression of CBS gene in the M1 group was lower compared to the AF-1 group. The expression of SAHH gene was the highest in the M3 group compared to the M1, M1/3, and AF-3 groups. The highest expression of BHMT gene was found in the M0, M1/3, and AF-1 groups, indicating enhanced re-methylation of homocysteine by betaine to Met. The lowest BHMT expression in M1, M3, M3-G, AF-2, and AF-3 groups compared to other treatments can be indicative of downregulation of remethylation in the liver. The alternate provision of methionine in a form of combination of low and high methionine containing diets seemed to support its efficient utilization in the salmon liver.

Dietary methionine availability affects the main factors involved in muscle protein turnover in rainbow trout (Oncorhynchus mykiss).

Methionine is a limiting essential amino acid in most plant-based ingredients of fish feed. In the present study, we aimed to determine the effect of dietary methionine concentrations on several main factors involved in the regulation of mRNA translation and the two major proteolytic pathways (ubiquitin-proteasome and autophagy-lysosomal) in the white muscle of rainbow trout (Oncorhynchus mykiss). The fish were fed for 6 weeks one of the three isonitrogenous diets providing three different methionine concentrations (deficient (DEF), adequate (ADQ) and excess (EXC)). At the end of the experiment, the fish fed the DEF diet had a significantly lower body weight and feed efficiency compared with those fed the EXC and ADQ diets. This reduction in the growth of fish fed the DEF diet was accompanied by a decrease in the activation of the translation initiation factors ribosomal protein S6 and eIF2α. The levels of the main autophagy-related markers (LC3-II and beclin 1) as well as the expression of several autophagy genes (atg4b, atg12 l, Uvrag, SQSTM1, Mul1 and Bnip3) were higher in the white muscle of fish fed the DEF diet. Similarly, the mRNA levels of several proteasome-related genes (Fbx32, MuRF2, MuRF3, ZNF216 and Trim32) were significantly up-regulated by methionine limitation. Together, these results extend our understanding of mechanisms regulating the reduction of muscle growth induced by dietary methionine deficiency, providing valuable information on the biomarkers of the effects of low-fishmeal diets.

Effects of dietary concentrations of methionine on growth performance and oxidative status of broiler chickens with different hatching weight

1. A study was conducted to evaluate the effects of two hatching weight (HW) levels and two dietary concentrations of methionine on the growth performance and oxidative status of broilers. Male Arbor Acres chickens were divided into two groups on their HW (low and high HW, H and L). Each HW group was then distributed into two subgroups, of similar HW, receiving either low or high dietary concentrations of methionine (4.9 g methionine/kg, LM; 5.9 g methionine/kg, HM). Thus, all day-old birds were distributed into 4 treatments (H-LM, H-HM, L-LM, L-HM) × 6 replicates × 10 birds for 21 d. 2. Broilers with high HW were heavier than those with low HW during the 21 d assay, which appeared to result from increased body weight gain rather than improved feed conversion efficiency. A higher dietary concentration of methionine (5.9 g/kg) improved growth performance of broilers with low HW in terms of body weight gain and feed conversion ratio. 3. Broilers with different HW had similar antioxidant status both in serum and liver. 4. Broilers given a diet containing 5.9 g/kg methionine had enhanced serum superoxide dismutase (SOD) activity and decreased hepatic malondialdehyde (MDA) content at day 7. 5. Broilers given a diet containing 5.9 g/kg methionine had a higher hepatic reduced glutathione (GSH):glutathione disulphide (GSSG) ratio than those given a diet containing 4.9 g/kg methionine at day 21. High dietary methionine concentration reduced hepatic GSH content and glutathione peroxidase (GPX) activity of broilers with high HW at day 7 and at day 21, respectively, but increased hepatic GSH content of broilers with low HW at day 7. 6. Although broilers with different HW had similar oxidative status as indicated by several parameters in blood and liver, HW can have positive effects on the subsequent growth performance of broilers, and a higher dietary methionine concentration (5.9 g/kg) can improve growth performance and antioxidant status in broilers exhibiting low HW.