Choline, betaine and methionine interactions in chickens, pigs and fish (including crustaceans)

Metabolic and microbiota response to arginine supplementation and cyclic heat stress in broiler chickens

Little attention has been paid to the biological role of arginine and its dietary supplementation in broilers under heat stress (HS) conditions. Therefore, the main aim of this study was to assess the response of broilers to arginine supplementation and cyclic HS, with a focus on liver, pectoral muscle, and blood metabolic profiles and the cecal microbiota. Day-old male Ross 308 broilers (n = 240) were placed in 2 rooms with 12 pens each for a 44-day trial. Pens were assigned to one of two groups (6 pens/group/room): the control group (CON) was given a basal diet in mash form and the treated group (ARG) was fed CON diet supplemented with crystalline L-arginine. The total arginine:lysine ratio of CON diet ranged between 1.02 and 1.07, while that of ARG diet was 1.20. One room was constantly kept at thermoneutral (TN) conditions, while the birds in the other room were kept at TN conditions until D34 and subjected to cyclic HS from D35 onwards (∼34°C; 9:00 A.M.–6:00 P.M.). Blood, liver, Pectoralis major muscle, and cecal content were taken from 2 birds per pen (12 birds/group/room) for metabolomics and microbiota analysis. Growth performance data were also collected on a pen basis. Arginine supplementation failed to reduce the adverse effects of HS on growth performance. Supplemented birds showed increased levels of arginine and creatine in plasma, liver, and P. major and methionine in liver, and reduced levels of glutamine in plasma, liver, and P. major. HS altered bioenergetic processes (increased levels of AMP and reduced levels of fumarate, succinate, and UDP), protein metabolism (increased protein breakdown to supply the liver with amino acids for energy production), and promoted the accumulation of antioxidant and protective molecules (histidine-containing dipeptides, beta-alanine, and choline), especially in P. major. Arginine supplementation may have partially counterbalanced the effects of HS on energy homeostasis by increasing creatine levels and attenuating the increase in AMP levels, particularly in P. major. It also significantly reduced cecal observed diversity, while HS increased alpha diversity indices and affected beta diversity. Results of taxonomic analysis at the phylum and family level are also provided.

Betaine supplementation fails to improve body composition: a systematic review and meta-analysis

Previous studies evaluating the effects of betaine supplementation on body composition offer contradictory findings. This systematic review and meta-analysis assessed the effects of betaine supplementation on body composition indices (body mass (BM), BMI, body fat percentage (BFP), fat mass (FM), fat-free mass (FFM)), and dietary intakes. Studies examining the effects of betaine supplementation on body composition and dietary intakes published up to August 2021 were identified through PubMed, the Cochrane Library, Web of Science, Embase, SCOPUS and Ovid databases. Betaine supplementation failed to significantly affect BM ((weighted mean difference (WMD): -0·40 kg, 95 % CI -1·46, 0·64), P = 0·447), BMI ((WMD: -0·05 kg/m², 95 % CI -0·36, 0·25), P = 0·719), BFP ((WMD: 0·26 %, 95 % CI -0·82, 1·36), P = 0·663), FM ((WMD: -0·57 kg, 95 % CI -2·14, 0·99), P = 0·473) and FFM ((WMD: 0·61 kg, 95 % CI -1·27, 2·49), P = 0·527). Subgroup analyses based on participant's age (< 40 and > 40 years), sex, BMI, trial duration (< 8 and ≥ 8 weeks), betaine supplementation dosage (< 4 and ≥ 4 g) and health status (healthy or unhealthy) demonstrated similar results. Other than a potential negligible increase in protein intake (WMD: 3·56 g, 95 % CI 0·24, 6·88, P = 0·035), no changes in dietary intakes were observed following betaine supplementation compared with control. The present systematic review and meta-analysis does not show any beneficial effects of betaine supplementation on body composition indices (BM, BMI, FM and FFM).

Microbiome and Metabolome Analyses in Different Closed-Circulation Aquarium Systems and Their Network Visualization

Understanding the causes of microbiome formation and its relationship to environmental conditions is important to properly maintain recirculating aquaculture systems (RASs). Although RAS has been applied to numerous fish types and environmental conditions (e.g., loading intensity), the effects of these environmental conditions (i.e., fish type and loading intensity) on microbiome composition are limitedly known. Therefore, we established three experimental aquarium tanks to explore the effects of fish type, loading intensity, filter pore size, and rearing day on microbiome compositions: (1) a tank for Acanthogobius flavimanus, (2) for Girella punctata, and (3) for G. punctata with higher loading intensity. Multivariate analysis showed that the microbial community composition differed among the tanks, indicating that the fish type and loading intensity significantly affected microbiome formation in rearing water. Some microbes, such as Sediminicola and Glaciecola, were detected at a higher loading intensity, indicating that these microbes might be an indicator of eutrophic conditions in the aquacultural systems. In addition, a partial correlation network revealed a connection between microbes and metabolites in the aquarium tanks. Such a microbe-metabolite network might be a clue to control the microbiome by adjusting the molecule abundance in the aquacultural environment.

Effects of dietary choline on liver lipid composition, liver histology and plasma biochemistry of juvenile yellowtail kingfish (Seriola lalandi)

Choline plays a crucial role in lipid metabolism for fish, and its deficiency in aquafeed has been linked to compromised health and growth performance. A 56-d experiment was conducted to examine the effects of dietary choline on lipid composition, histology and plasma biochemistry of yellowtail kingfish (Seriola lalandi; YTK; 156 g initial body weight). The dietary choline content ranged from 0·59 to 6·22 g/kg diet. 2-Amino-2-methyl-1-propanol (AMP) (3 g/kg) was added to diets, except for a control diet, to limit de novo choline synthesis. The results showed that the liver lipid content of YTK was similar among diets containing AMP and dominated by NEFA. In contrast, fish fed the control diet had significantly elevated liver TAG. Generally, the SFA, MUFA and PUFA content of liver lipid in fish fed diets containing AMP was not influenced by choline content. The SFA and MUFA content of liver lipid in fish fed the control diet was similar to other diets except for a decrease in PUFA. The linear relationship between lipid digestibility and plasma cholesterol was significant, otherwise most parameters were unaffected. When AMP is present, higher dietary choline reduced the severity of some hepatic lesions. The present study demonstrated that choline deficiency affects some plasma and liver histology parameters in juvenile YTK which might be useful fish health indicators. Importantly, the present study elucidated potential reasons for lower growth in choline-deficient YTK and increased the knowledge on choline metabolism in the fish.

Dietary betaine reduces plasma homocysteine concentrations and improves bone strength in laying hens

1. This study tested the hypothesis that the methyl-donor properties of betaine could reduce homocysteine concentrations, which has been recognised in a previous genetics study to be linked to bone quality. This was combined with phytase treatment, as phosphorus is critical for bone mineralisation.2. Using a 2 × 2 factorial arrangement, a total of 1920 Lohmann LSL-lite chickens housed as 24 replicates of 20 chickens were fed one of four diets containing dietary betaine (0 or 1000 mg/kg) and phytase (300 or 1000 FTU/kg) from one day old until end-of-lay. Blood and bone samples were collected at 45 and 70 weeks of age.3. Hens fed betaine had lower plasma homocysteine level (P < 0.05), higher tibia breaking strength (P < 0.05) and higher tibia bone density (P < 0.05).4. Egg production and quality was excellent throughout the study and were not affected by the dietary treatments.5. The addition of dietary betaine was successful at reducing plasma homocysteine concentrations and improving bone strength in laying hens, which could be used as an intervention to alleviate welfare concerns.

Effects of Betaine Supplementation on Live Performance, Selected Blood Parameters, and Expression of Water Channel and Stress-Related mRNA Transcripts of Delayed Placement Broiler Chicks

This study examined the effect of supplemental betaine on live performance, selected blood parameters, and gene expression of water channel proteins (Aquaporins, AQP) of broiler chicks delayed in placement for 48 h post-hatch. In total, 540 newly-hatched male broiler chicks were obtained from a local hatchery and were randomly allotted to one of five treatments with nine replicates per treatment (12 chicks per replicate). Chicks were either placed immediately, control; held for 48 h post-hatch with no access to feed or water, Holdnull; held for 48 h with free access to drinking water only, HoldW; held for 48 h with free access to drinking water supplemented with 1 ml per L of betaine solution (40% betaine), HoldB1; or held for 48 h with free access to drinking water supplemented with 2 ml per L of betaine solution (40% betaine), HoldB2 group. The results showed that post-hatch holding for 48 h depressed feed intake and body weight gain during the entire 15 d study period with no beneficial effect of supplemental betaine. Chicks in the HoldB2 group had elevated serum glucose, triglycerides, and aspartate aminotransferase 48 h post-hatch. Early water deprivation directly affected the brain proopiomelanocortin (POMC) and hepatic glucocorticoid receptors (GR) expression and induced significant changes in various aquaporins (AQP1, AQP2, AQP4, and AQP9). In conclusion, betaine supplementation to chicks held for 48 h post-hatch resulted in some changes in blood biochemical indices with no effects on performance during the first 15 days of life. The results suggest that betaine supplementation could ameliorate the stressful effects of water deprivation on POMC and GR expression and maintain cellular osmosis through interactions with variable aquaporins expression, particularly the AQP1 and AQP2. Further investigations are required to investigate the molecular mechanisms underlying the selective regulatory expression of different aquaporins in relation to betaine supplementation.

Reconstruction of Eriocheir sinensis Y-organ Genome-Scale Metabolic Network and Differential Analysis After Eyestalk Ablation

Genome-scale metabolic network (GSMN) has been proven to be a useful tool for the system analysis of organism metabolism and applied to deeply explore the metabolic functions or mechanisms in many organisms, including model or non-model organisms. However, the systematic studies on the metabolisms of aquatic animals are seldom reported, especially the aquatic crustaceans. In this work, we reconstructed an Eriocheir sinensis Y-organ GSMN based on the transcriptome sequencing of Y-organ, which includes 1,645 reactions, 1,885 unigenes, and 1,524 metabolites distributed in 100 pathways and 11 subsystems. Functional module and centrality analysis of the GSMN show the main metabolic functions of Y-organ. Further analysis of the differentially expressed unigenes in Y-organ after eyestalk ablation reveals that 191 genes in the network were up-regulated and 283 were down-regulated. The unigenes associated with the ecdysone synthetic pathway were all up-regulated, which is consistent with the report on the increasing secretion of ecdysone after eyestalk ablation. Besides, we compared the Y-organ GSMN with that of E. sinensis eyestalk and hepatopancreas, and we analyzed the specific metabolisms in each organ. The specific metabolisms and pathways of these three networks are closely related to their corresponding metabolic functions. The GSMN reconstructed in this work provides a new method and many novel clues for further understanding the physiological function of Y-organ. It also supplies a new platform for the investigation of the interactions among different organs in the growth process of E. sinensis.

The effects of betaine supplementation in diets containing different levels of crude protein and methionine on the growth performance, blood components, total tract nutrient digestibility, excreta noxious gas emission, and meat quality of the broiler chickens

The effects of betaine supplementation on growth performance, blood components, nutrient digestibility, excreta noxious gas emission, and meat quality of broiler chickens were examined using different dietary crude protein (CP) and methionine (Met) levels. A total of 768 Ross 308 broiler chickens were allotted to four treatments, with 12 replications of each treatment conducted over 6 wk. Treatments were factorially designed, with 2 levels of CP [Starter: CP 21% (low Met) and 23% (high Met); Finisher: CP 18% (low Met) and 20% (high Met)] and 2 levels of betaine supplementation (0 and 0.12%). Body weight gain and feed conversion improved significantly as dietary levels of protein increased (P < 0.05), but the results for betaine supplementation differed. The concentrations of serum total protein, albumin, and glutathione peroxidase (GPx) were elevated by either the supplementary betaine or the CP (P < 0.05). In addition, serum albumin concentration significantly increased in groups fed low CP amounts and betaine 0.12% compared with groups fed low CP only (P < 0.05). Total tract digestibility of nitrogen in broilers fed high CP amounts or 0.12% betaine, was observed to be greater than that in groups fed low CP amounts or no betaine treatment (P < 0.05). Supplemental betaine affected excreta ammonia gas emission, and hydrogen sulfide concentrations decreased significantly in low CP-fed groups (P < 0.05). Breast meat quality and relative organ weights were not influenced by CP levels or dietary betaine supplementation. These results suggest that betaine does not increase productivity, but may affect serum total protein, albumin, GPx, excreta ammonia emission, and nitrogen digestibility in broiler chickens. In addition, betaine supplementation is more effective in increasing serum albumin concentration when it was added in low CP (low Met) diets.

Nutritional requirements of meat-type and egg-type ducks: what do we know?

The demand for duck meat, duck eggs, and associated products is increasing each year. Classic and modern selection programs have been applied to enhance the economic traits of ducks to satisfy the requirements of consumers and enhance the incomes of producers. The nutritional requirements of unselected ducks may not be adequate, however, to fulfill the potential productivity performance of modern birds, including both meat-type and egg-type ducks. In particular, an imbalanced diet is associated with low productive performance and signs of nutritional deficiency (if insufficient nutrients are supplied), as well as with high feed costs and manure problems that reflect flock health and welfare (if excessive nutrients are supplied). Thus, the main aim of this review is to summarize the results of previous studies that estimated the nutrient requirements of meat-type and egg-type ducks in order to evaluate current knowledge and to identify further issues that need to be addressed. In addition, the results obtained in previous studies are compared in order to understand how to lower commercial feed costs, fulfill the genetic potential of selected ducks, protect the environment from pollution, and satisfy the welfare and health needs of ducks.

Betaine and arginine supplementation of low protein diets improves plasma lipids but does not affect hepatic fatty acid composition and related gene expression profiling in pigs

BACKGROUND

The individual and combined effects of betaine and arginine supplemented to reduced protein diets were investigated on plasma metabolites, hepatic fatty acid composition and mRNA levels of lipid-sensitive factors in commercial pigs. Betaine has previously been shown to reduce carcass fat deposition and arginine improves meat quality of finishing pigs. Forty male crossbred pigs were randomly assigned to one of five diets (n = 8): 160 g kg^-1 of crude protein (NPD), 130 g kg^-1 of crude protein (RPD), RPD with 3.3 g kg^-1 of betaine, RPD with 15 g kg^-1 of arginine, and RPD with 3.3 g kg^-1 of betaine and 15 g kg^-1 of arginine.

RESULTS

The restriction of dietary protein increased total lipids (P < 0.001), total cholesterol (P < 0.001), high-density lipoprotein-cholesterol (P < 0.001) and low-density lipoprotein cholesterol (P < 0.001). Betaine and arginine, individually or combined, reduced the majority of plasma lipids (P < 0.05) without affecting total fatty acids in the liver and the overall gene expression pattern.

CONCLUSION

These findings suggest a positive effect of betaine and arginine, singly or combined, by reversing plasma lipids increase promoted by dietary protein restriction. © 2017 Society of Chemical Industry.

Expressão gênica de IGF-I e GHR no fígado e no músculo do peito de codornas de corte suplementadas com diferentes níveis de metionina em duas gerações sucessivas

RESUMO Este estudo foi desenvolvido com o objetivo de avaliar a expressão gênica do fator de crescimento semelhante à insulina I (IGF-I) e do receptor do hormônio do crescimento (GHR) no fígado e no músculo do peito de codornas de corte, alimentadas com dietas contendo diferentes níveis de suplementação de metionina, em duas gerações sucessivas. Foram utilizadas codornas dos 22 aos 42 dias de idade, distribuídas em três e cinco tratamentos na primeira e na segunda geração, respectivamente. Ao final, as aves foram abatidas por deslocamento cervical, sendo coletados fígado e músculo do peito para extração de RNA total. O cDNA foi amplificado usando primers específicos para os genes analisados. Os resultados mostraram que a expressão dos genes GHR e IGF-I sofreu influência da suplementação. No quinto tratamento, em que apenas a primeira geração recebeu uma suplementação acima do padrão das exigências para o período, houve uma expressão significativamente maior do GHR tanto no músculo do peito como no fígado e igualmente do IGF-I no músculo, levando a concluir que o excesso de metionina na dieta torna-se tóxica para as aves. Apesar de a expressão dos genes ter sofrido influência da adição de metionina nos níveis estudados, não foi observada diferença no consumo alimentar, na conversão alimentar e no peso das aves.

Effect of equi-molar dietary betaine and choline addition on performance, carcass quality and physiological parameters of pigs

Betaine and its precursor choline were compared in their efficiency in affecting the performance, carcass traits, and liver betaine concentration of growing-finishing pigs. Individually penned Finnish Landrace and Yorkshire pigs and their crosses (30 kg; no. = 70) were offered the basal diet with no added betaine or choline, or the basal diet supplemented with low to moderate doses (250, 500 or 1000 mg/kg) of betaine (Betafin® S1), or with a similar molar amount of choline (578, 1155 or 2310 mg/kg of choline chloride). The maize-soya-bean-meal basal diet was formulated to contain 12·3 MJ/kg digestible energy, 155 g/kg crude protein and 7·4, 4·4 and 4·3 g/kg digestible lysine, threonine and methionine + cystine, respectively. Oat hull meal (100 g/kg) was added to reduce the dietary energy concentration. The pigs were on a restricted feeding level, 1·5 to 3·0 kg food per day (proportionately 0·8 of ad libitum intake) for 75 days. Daily weight gain and food-to-gain ratio improved linearly (P < 0·01) with increasing dietary betaine. Carcass weight increased linearly (P < 0·01) but slaughter loss proportion, backfat and sidefat thicknesses and lean proportions in ham and carcass were unaffected by dietary betaine level. Liver betaine level increased linearly (by up to a proportion of 0·62 in comparison with the control) with dietary betaine addition (F < 0·05) and betaine tended to improve linearly the tensile strength of the proximal ileum (P = 0·07). The presence of choline had no effect on any of these parameters. These results indicate that low to moderate doses of dietary betaine improved the growth and the efficiency of food utilization of growing-finishing pigs. Pigs on betaine diets had heavier carcasses without a relative increase in carcass fat. Choline had no such effects in pigs offered the restricted amount of diet. Liver betaine concentration increased with level of betaine in the diet whereas the betaine precursor choline did not affect hepatic betaine.

Influence of betaine and arginine supplementation of reduced protein diets on fatty acid composition and gene expression in the muscle and subcutaneous adipose tissue of cross-bred pigs

The isolated or combined effects of betaine and arginine supplementation of reduced protein diets (RPD) on fat content, fatty acid composition and mRNA levels of genes controlling lipid metabolism in pig m. longissimus lumborum and subcutaneous adipose tissue (SAT) were assessed. The experiment was performed on forty intact male pigs (Duroc×Large White×Landrace cross-breed) with initial and final live weights of 60 and 93 kg, respectively. Pigs were randomly assigned to one of the following five diets (n 8): 16·0 % of crude protein (control), 13·0 % of crude protein (RPD), RPD supplemented with 0·33 % of betaine, RPD supplemented with 1·5 % of arginine and RPD supplemented with 0·33 % of betaine and 1·5 % of arginine. Data confirmed that RPD increase intramuscular fat (IMF) content and total fat content in SAT. The increased total fat content in SAT was accompanied by higher GLUT type 4, lipoprotein lipase and stearoyl-CoA desaturase mRNA expression levels. In addition, the supplementation of RPD with betaine and/or arginine did not affect either IMF or total fat in SAT. However, dietary betaine supplementation slightly affected fatty acid composition in both muscle and SAT. This effect was associated with an increase of carnitine O-acetyltransferase mRNA levels in SAT but not in muscle, which suggests that betaine might be involved in the differential regulation of some key genes of lipid metabolism in pig muscle and SAT. Although the arginine-supplemented diet decreased the mRNA expression level of PPARG in muscle and SAT, it did not influence fat content or fatty acid composition in any of these pig tissues.

Metabolic responses of the isopod Porcellionides pruinosus to nickel exposure assessed by (1)H NMR metabolomics

This work aimed at characterizing the metabolome of the isopod Porcellionides pruinosus and at assessing its variations over 14 days under laboratory culture conditions and upon exposure to the contaminant metal Nickel (Ni). The spectral profiles obtained by (1)H NMR spectroscopy were thoroughly assigned and subjected to multivariate analysis in order to highlight consistent changes. Over 50 metabolites could be identified, providing considerable new knowledge on the metabolome of these model organisms. Several metabolites changed non-linearly with Ni dose and exposure time, showing distinct variation patterns for initial (4 days) and later time points (7 and 14 days). In particular, at day 4, several amino acids were increased and sugars were decreased (compared to controls), whereas these variations were inverted for longer exposure, possibly reflecting earlier and more intensive moulting. Other variations, namely in betaines and choline-containing compounds, were suggested to relate with osmoregulation and detoxification mechanisms. Ni also had a marked effect on several nucleotides (increased upon exposure) and a moderate impact on lipids (decreased upon exposure). Overall, this study has provided new information on the Ni-induced metabolic adaptations of the P. pruinosus isopod, paving the way for improved mechanistic understanding of how these model organisms handle soil contamination.

SIGNIFICANCE

This study provided, for the first time to our knowledge, a detailed picture of the NMR-detectable metabolome of terrestrial isopods and of its fluctuations in time and upon exposure to the contaminant metal Nickel. Several time- and dose-dependent changes were highlighted, providing mechanistic insight into how these important model organisms handle Ni contamination.

The contribution of portal drained viscera to circadian homocysteinemia in pigs

Homocysteine (Hcy) is an intermediary S-containing amino acid produced by the methylation process within all cells. It is known as a powerful pro-oxidant with multiple deleterious effects on immune and physiological functions. Blood plasma total Hcy (tHcy), the most common indicator of Hcy status, can be reduced by dietary folates or vitamin B(12) in pigs as in most mammalians. In humans, homocysteinemia is routinely assessed after an overnight fast (≥ 12 h) although information is not available on circadian tHcy changes. Using a subgroup of pigs from a study on portal appearance of vitamin B(12) after a single meal containing 0, 25 or 250 μg of cyanocobalamin, the present study aimed to report the circadian profile of postmeal blood plasma tHcy and estimate the contribution of portal drained viscera (PDV) to the systemic tHcy. Four pigs (39.7 ± 1.1 kg BW) were surgically equipped at 101.0 ± 8.2 d of age with catheters in the portal vein and carotid artery; an ultrasonic flow probe was also fitted around the portal vein for blood flow recordings. Blood samples were collected simultaneously from the 2 catheters once before meal and at least every hour during 24 h after ingestion of 1.2 kg of a vitamin-free semipurified diet. Arterial tHcy changed considerably during the 24-h postmeal period (P < 0.001; SE = 0.8). In fact, from 12.3 μM 10 min before meal, tHcy gradually reached a maximum of 23.4 μM 13 h postmeal and returned to 15.5 μM 23 h after the meal. Net fluxes of tHcy across PDV were not influenced by levels of dietary vitamin B(12), postprandial time, or their interaction (P > 0.25); average net flux did not differ from zero (P > 0.08). These results suggest that systemic Hcy following a meal originates from metabolic pools other than PDV. It appears that an overnight fast of 12 h will reflect the peak rather than the basal value for tHcy. The duration of the fasting period is therefore a critical factor for a reliable interpretation of tHcy homeostasis in pigs. Such information may be also relevant for human health and nutrition because pig is recognized as a reliable model for Hcy metabolism.

Effects of Betaine on Energy Utilization in Growing Pigs - A Review

One of the well known biological functions of betaine is that of a methyl donor. Therefore, betaine may partly replace choline and methionine in the diet. Another widely documented role of betaine is to restore and maintain the osmotic balance. As an organic osmotic compound, betaine regulates the water balance, thus exerting a stabilizing influence on tissue metabolism, particularly within the digestive tract. As a donor of methyl groups necessary for various reactions in the body, betaine is indirectly involved in lipid metabolism. Due to its metabolic functions, betaine is also believed to play a significant role in energy metabolism in pigs. Of particular note are the results of experiments in which a positive effect of betaine supplementation was observed as the energy content of the diet was decreased.

Influence of acute cadmium exposure on the liver proteome of a teleost fish, ayu (Plecoglossus altivelis)

Cadmium (Cd) is a toxic heavy metal that causes the disruption of a variety of physiological processes. In this study, the effect of Cd on liver proteome of ayu, Plecoglossus altivelis, was investigated by two-dimensional gel electrophoresis (2-DE) and matrix assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF-MS/MS). Twenty-three altered protein spots were successfully identified. They were involved in oxidative stress response, metal metabolism, methylation, and so on. The mRNA expression of 60S acidic ribosomal protein P0, heat shock protein 70, apolipoprotein A-I, betaine-homocysteine S-methyltransferase, parahox cluster neighbor, and transferrin was subsequently determined by real-time PCR. The mRNA expression of these genes was consistent with proteomic results. These findings enrich our knowledge on the influence of Cd toxicity to teleost fish, and may be worthy of further investigation to develop biomarkers.

The effect of choline and cystine on the utilisation of methionine for protein accretion, remethylation and trans-sulfuration in juvenile shrimp Penaeus monodon

This 35-d feeding experiment examined in juvenile shrimp Penaeus monodon (3·3 g initial body weight) the effects of methionine (Met), choline and cystine on protein accretion and the activity of two key enzymes of remethylation (betaine–homocysteine methyltransferase; BHMT) and trans-sulfuration (cystathionine β-synthase; CBS). The interaction between Met and choline was tested using semi-purified diets either adequate or limiting (30 or 50 %) in total sulphur amino acid (SAA) content with a constant cystine:Met ratio. The diets contained either basal or excess choline (3 v. 7 g/kg feed). Cystine was added to two other 30 and 50 % Met-limiting diets to adjust the SAA supply to that of the control diet in order to evaluate the interaction between Met and cystine. As expected, N accretion was significantly lower with the SAA-limiting diets but increased back to control levels by the extra choline or cystine, demonstrating their sparing effect on Met utilisation for protein accretion. We show, for the first time, the activities of BHMT and CBS in shrimp hepatopancreas. Only BHMT responded to the SAA deficiencies, whereas the extra choline and cystine did not stimulate remethylation or down-regulate trans-sulfuration. Our data also suggest the capacity of P. monodon to synthesise taurine, being significantly affected by the cystine level in the 30 % SAA-limiting diets. Further research is warranted to better understand the metabolic regulation of taurine synthesis in shrimp and of the observed Met-sparing effects.

Proteomic analysis on the alteration of protein expression in gills of ayu (Plecoglossus altivelis) associated with salinity change

Gill is the primary osmoregulatory organ for euryhaline fish to acclimate salinity change. The effect of salinity on gill proteome in ayu, Plecoglossus altivelis, was investigated by two-dimensional gel electrophoresis (2-DE) and matrix assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF-MS/MS). Eight of eighteen altered proteins were successfully identified. They are involved in osmoregulation, cytoskeleton, energy metabolism, and stress response. Our results showed that vinculin, echinoderm microtubule-associated protein like protein 1, pyruvate kinase, betaine-homocysteine methyltransferase (BHMT), transaldolase, glyceraldehyde 3-phosphate dehydrogenase, and heat shock protein 70 (HSP70) were down-regulated, whereas cofilin was up-regulated when ayu transferred from fresh water (FW) to brackish water (BW). Partial cDNA sequences of BHMT, HSP70, Na(+)/K(+) ATPase (NKA) alpha-subunit and 18S rRNA genes were subsequently determined and used for 2-DE data verification by real-time PCR. Gill BHMT and HSP70 mRNAs decreased significantly in BW-transferred ayu, while NKA alpha-subunit mRNA had no significant change. It was suggested that cell volume-regulatory response, especially the protection by the BHMT/betaine system might play an important role in ayu acclimation to salinity change.

Potential nutritional and physiological functions of betaine in livestock

The present review summarises the potential nutritional and physiological functions of betaine as a feed additive in relation to performance criteria in livestock production. Betaine, the trimethyl derivative of the amino acid glycine, is a metabolite of plant and animal tissues. In plants, betaine is particularly synthesised and accumulated as an osmoprotectant against salt and temperature stress. In animals, betaine is the product of choline oxidation or it originates from nutritional sources. Over the past decades, numerous studies have been carried out to investigate the potential effects of betaine supplementation on animal performance. Due to its chemical structure, betaine shows the characteristics of a dipolar zwitterion resulting in osmoprotective properties. Promoting effects on the intestinal tract against osmotic stress occurring during diarrhoea or coccidiosis have been reported following betaine supplementation in pigs and poultry. There is also some evidence that dietary betaine may improve the digestibility of specific nutrients. As a product of choline oxidation, betaine is involved in transmethylation reactions of the organism. Betaine as a methyl donor provides its labile methyl groups for the synthesis of several metabolically active substances such as creatine and carnitine. Supplementation with betaine may decrease the requirement for other methyl donors such as methionine and choline. There is also some evidence for enhanced methionine availability after dietary supplementation of betaine resulting in improved animal performance. Alterations in the distribution pattern of protein and fat in the body have been reported following betaine supplementation. A more efficient use of dietary protein may result from a methionine-sparing effect of betaine, but also direct interactions of betaine with metabolism-regulating factors have to be considered. Though the mode of action of betaine as a carcass modifier remains open, there is, however, growing evidence that betaine could have a positive impact both on animal performance and carcass quality.

Effect of betaine on growth hormone pulsatile secretion and serum metabolites in finishing pigs

An experiment was conducted to investigate the effect of dietary betaine (0%, 0.125%) on growth performance, growth hormone (GH) pulsatile secretion and serum metabolites in crossbred finishing pigs. Three replications of eight pigs (four barrows and four gilts) were used for each treatment, and blood samples for the determination of GH pulsatile secretion were collected every 15 min for 3 h. The results showed that betaine supplementation resulted in 5.45% (p<0.05) increase in average daily gain, whereas average daily feed intake and feed to gain ratio were not affected. Serum basal GH level, mean GH level and GH pulse amplitude were elevated by 41.79% (p<0.01), 48.98% (p<0.01) and 35.05% (p<0.05), respectively, with betaine treatment, but GH pulse frequency and pulse duration remained unchanged (p>0.05). Serum urea nitrogen concentration in pigs fed betaine was 21.58% lower than that of controls (p<0.01), whereas total protein level was significantly increased with betaine supplementation (p<0.05). The study suggests that betaine could promote growth by enhancing GH secretion in finishing pigs.

Homocysteine Remethylation in Broilers Fed Surfeit Choline or Betaine and Varying Levels and Sources of Methionine from Eight to Twenty-Two Days of Age

Experiments were conducted to assess the effect of surfeit choline (CHOL) or betaine (BET) on growth performance and homocysteine (HCY) remethylation of young broilers fed graded levels of DL-Met (DLM) or 2-hydroxy-4-(methylthio) butanoic acid (HMB). In Experiment 1, a corn-peanut meal diet deficient in Met (0.25% digestible) and Cys (0.28% digestible) was fed; treatments were formulated to contain graded levels (0, 0.04, or 0.08%) of Met from DLM or 0.04% HMB (adjusted for 88% purity) that were fed in the presence or absence of surfeit isomethyl CHOL (0.25%) or BET (0.28%). In Experiment 2, identical treatments were used, but an additional level of HMB (0.08%) was fed, and the basal diet was adequate in Cys (0.43% digestible). There was no overall effect of CHOL or BET on growth performance in Experiments 1 and 2 (P > 0.05); a significant improvement (P < 0.05) in weight gain and feed efficiency did occur with CHOL and BET addition to the basal diet in Experiment 2. In both experiments, weight gain increased linearly (P < 0.05) with the addition of DLM or HMB. Slope ratio methodology was used to assess HMB efficacy in Experiment 2. In the presence of adequate Cys, HMB efficacy was 81.3%; addition of surfeit BET or CHOL had minimal effect on efficacy. The stable isotope study revealed that CHOL and BET addition to diets deficient in Met and Cys or Met alone increased HCY remethylation. It also showed that CHOL and BET have greater influence on folate-dependent remethylation of HCY (via Met synthase) than on BET-dependent remethylation (via BET-HCY methyltransferase) and that levels of CHOL and BET and type of S amino acid deficiency effect remethylation and HMB efficacy.

Dietary betaine supplementation affects energy metabolism of pigs

The effect of dietary betaine supplementation on energy partitioning in growing pigs under energy-restricted dietary conditions was assessed. The effect of betaine on the adaptation in energy metabolism of pigs over time after a change in diet and housing also was studied. Six groups of 14 group-housed barrows were assigned to one of two experimental diets: control or betaine-supplemented (0 or 1.29 g/kg of feed). Diets were corn- and soybean meal-based and were formulated to be limiting in energy content but sufficient in amino acids. The experiment comprised a 3-wk adaptation and a 3-wk experimental period. At the start of the experimental period, initial BW was 46 kg, each group of pigs was housed in a climate-controlled respiration chamber, and all pigs were subjected to a change in diet. During the experimental period, diets were diluted with 10% oat hulls. Pigs were fed at 2.5 times the energy requirements for maintenance, and during the experimental period, heat production, energy, and nitrogen balances were measured weekly. Metabolizibility of energy did not differ (P > 0.10) between diets. Averaged over the experimental period, betaine reduced heat production (P < 0.05) and energy requirements for maintenance (P < 0.10) and consequently increased energy retention (P < 0.10). Moreover, the difference in heat production between diets increased with time (P < 0.05). Similarly, the effect of betaine on the energy requirements for maintenance changed with time (P < 0.05). Maintenance requirements were similar in wk 1 and were decreased by betaine supplementation by 5.5% during wk 3 (477 vs. 452 kJ/[kg(0.75) x d]). Results of this study show that dietary betaine supplementation affects energy partitioning by growing pigs. However, based on the observed time-related changes in energy partitioning, it was concluded that dietary betaine supplementation did not influence adaptation by pigs to a change in housing and diet.

Betaine does not improve performance of laying hens when the diet contains adequate choline

An experiment was conducted with Hy-Line W36 hens to determine possible benefits from adding betaine to the diet of commercial laying hens. There was no benefit from the substitution of betaine for choline as measured by egg production, egg weight, egg content, or weight gain.