Effects of methionine deficiencies on plasma levels of thyroid hormones, insulin-like growth factors-I and -II, liver and body weights, and feed intake in growing chickens

The Impact of Essential Amino Acids on the Gut Microbiota of Broiler Chickens

The research involving the beneficial aspects of amino acids being added to poultry feed pertaining to performance, growth, feed intake, and feed conversion ratio is extensive. Yet currently the effects of amino acids on the gut microbiota aren't fully understood nor have there been many studies executed in poultry to explain the relationship between amino acids and the gut microbiota. The overall outcome of health has been linked to bird gut health due to the functionality of gastrointestinal tract (GIT) for digestion/absorption of nutrients as well as immune response. These essential functions of the GI are greatly driven by the resident microbiota which produce metabolites such as butyrate, propionate, and acetate, providing the microbiota a suitable and thrive driven environment. Feed, age, the use of feed additives and pathogenic infections are the main factors that have an effect on the microbial community within the GIT. Changes in these factors may have potential effects on the gut microbiota in the chicken intestine which in turn may have an influence on health essentially affecting growth, feed intake, and feed conversion ratio. This review will highlight limited research studies that investigated the possible role of amino acids in the gut microbiota composition of poultry.

The Role of Amino Acids in Non-Enzymatic Antioxidant Mechanisms in Cancer: A Review

Currently, the antioxidant properties of amino acids and their role in the physicochemical processes accompanying oxidative stress in cancer remain unclear. Cancer cells are known to extensively uptake amino acids, which are used as an energy source, antioxidant precursors that reduce oxidative stress in cancer, and as regulators of inhibiting or inducing tumor cell-associated gene expression. This review examines nine amino acids (Cys, His, Phe, Met, Trp, Tyr, Pro, Arg, Lys), which play a key role in the non-enzymatic oxidative process in various cancers. Conventionally, these amino acids can be divided into two groups, in one of which the activity increases (Cys, Phe, Met, Pro, Arg, Lys) in cancer, and in the other, it decreases (His, Trp, Tyr). The review examines changes in the metabolism of nine amino acids in eleven types of oncology. We have identified the main nonspecific mechanisms of changes in the metabolic activity of amino acids, and described direct and indirect effects on the redox homeostasis of cells. In the future, this will help to understand better the nature of life of a cancer cell and identify therapeutic targets more effectively.

Enhancing Metabolism and Milk Production Performance in Periparturient Dairy Cattle through Rumen-Protected Methionine and Choline Supplementation

For dairy cattle to perform well throughout and following lactations, precise dietary control during the periparturient phase is crucial. The primary issues experienced by periparturient dairy cows include issues like decreased dry matter intake (DMI), a negative energy balance, higher levels of non-esterified fatty acids (NEFA), and the ensuing inferior milk output. Dairy cattle have always been fed a diet high in crude protein (CP) to produce the most milk possible. Despite the vital function that dairy cows play in the conversion of dietary CP into milk, a sizeable percentage of nitrogen is inevitably expelled, which raises serious environmental concerns. To reduce nitrogen emissions and their production, lactating dairy cows must receive less CP supplementation. Supplementing dairy cattle with rumen-protected methionine (RPM) and choline (RPC) has proven to be a successful method for improving their ability to use nitrogen, regulate their metabolism, and produce milk. The detrimental effects of low dietary protein consumption on the milk yield, protein yield, and dry matter intake may be mitigated by these nutritional treatments. In metabolic activities like the synthesis of sulfur-containing amino acids and methylation reactions, RPM and RPC are crucial players. Methionine, a limiting amino acid, affects the production of milk protein and the success of lactation in general. According to the existing data in the literature, methionine supplementation has a favorable impact on the pathways that produce milk. Similarly, choline is essential for DNA methylation, cell membrane stability, and lipid metabolism. Furthermore, RPC supplementation during the transition phase improves dry matter intake, postpartum milk yield, and fat-corrected milk (FCM) production. This review provides comprehensive insights into the roles of RPM and RPC in optimizing nitrogen utilization, metabolism, and enhancing milk production performance in periparturient dairy cattle, offering valuable strategies for sustainable dairy farming practices.

Optimal Standardized Ileal Digestible Total Sulfur Amino Acids to Lysine REQUIREMENTS Are Increased in Nursery Pigs Raised under Antibiotic-Free Feeding Regime

Simple Summary

Total sulfur amino acids play a critical role in numerous biological functions, including antioxidative status and immunity, as well as protein synthesis. Weaning pigs commonly face multiple stressors which can impair their gut integrity and growth performance. Antibiotic removal from the diets in weaning pigs can stimulate immune response and divert nutrients from growth to optimize immune function. The objective of the current two studies was to determine the optimal ratio of the standardized ileal digestible (SID) total sulfur amino acid to lysine (TSAA:Lys) in nursery pigs under an antibiotics-free feeding regime. The results demonstrated that the optimal SID TSAA:Lys for nursery pigs raised without antibiotics during the first 21 d post-weaning was 62 to 72% in terms of growth performance, whereas the optimal SID TSAA:Lys was approximately 58% in terms of growth performance in the late nursery phase.

Abstract

This study aimed to investigate the effect of increasing the standardized ileal digestible (SID) total sulfur amino acid to lysine (TSAA:Lys) on the growth performance of nursery pigs raised with or without antibiotics (AGP) and to determine the optimal SID TSAA:Lys in nursery pigs raised without AGP. In Exp. 1, 924 nursery pigs (7.9 ± 1.3 kg), blocked by initial BW and sex, were randomly allotted to one of six treatments, with seven pens per treatment and twenty-two pigs per pen. The treatments were arranged in a 2 × 3 factorial design, with two AGP levels (0 or 50 mg/kg Carbodox) and three levels of SID TSAA:Lys (51.0, 58.5 or 66.0%). In Exp. 2, 990 weaned piglets (5.1 ± 0.9 kg), blocked by initial BW and sex, were randomly allotted to one of five dietary treatments (SID TSAA:Lys at 51, 58, 65, 72 or 79%) in the absence of AGP, with nine pens per treatment and twenty-two pigs per pen. Competing heteroskedastic models including broken-line linear (BLL), broken-line quadratic (BLQ), and quadratic polynomial (QP) were fitted for the growth performance data to estimate the optimal TSAA:Lys. In Exp. 1, AGP supplementation increased (p < 0.05) ADG and ADFI during the 21 d period. Increasing SID TSAA:Lys in the diets with AGP did not affect growth performance; however, increasing SID TSAA:Lys in the diets without AGP resulted in a linear increase (p < 0.05) in ADG and G:F. In Exp. 2, the best-fitting models for ADG and G:F from d 0 to 21 post-weaning were BLL, which yielded the optimal SID TSAA:Lys of 62% and 72%, respectively. The best-fitting models for ADG and G:F from d 21 to 42 post-weaning were BLL, which yielded the optimal SID TSAA:Lys of 59% and 58%, respectively. In conclusion, SID TSAA to Lys requirements under an antibiotic-free feeding regime during the first 21 d post-weaning were 62% and 72% in terms of ADG and G:F, respectively, whereas an SID TSAA:Lys of approximately 58% was required to maximize ADG and G:F for the late nursery phase.

Methionine Deficiency Affects Liver and Kidney Health, Oxidative Stress, and Ileum Mucosal Immunity in Broilers

Methionine (Met) is the first limiting amino acid in broiler diets, but its unclear physiological effects hamper its effective use in the poultry production industry. This study assessed the effect of a Met-deficient (MD) diet on chicken liver and kidney health, exploring the associated mechanisms of antioxidant capacity and ileum mucosal immunity. Seventy-two broilers were administered either the control diet (0.46% Met in starter diet, 0.36% Met in grower diet) or the MD diet (0.22% Met in starter diet, 0.24% Met in grower diet). Liver and kidney samples were collected every 14 days for anatomical, histological, and ultrastructural analyses, accompanied by oxidative stress assessment. Meanwhile, T- and B-lymphocyte abundance and essential cytokine gene expression were measured in the ileum, the center of the gut–liver–kidney axis. Signs of kidney and liver injury were observed morphologically in the MD group at 42 days of age. Furthermore, aspartate aminotransferase, alanine aminotransferase, creatinine, and uric acid levels were decreased in the MD group compared with the control group, accompanied by decreased superoxide dismutase activity, increased malondialdehyde content, decreased numbers of T and B lymphocytes, and decreased cytokine expression in the ileum, such as IL-2, IL-6, LITAF, and IFN-γ. These results suggest that MD can induce kidney and liver injury, and the injury pathway might be related to oxidative stress and intestinal immunosuppression.

Effect of digestible amino acids to energy ratios on performance and yield of two broiler lines housed in different grow-out environmental temperatures

Two broiler lines, Line A and Line B, were fed experimental diets from 22 to 42 d with objectives to determine effects of digestible amino acids (AA) to metabolizable energy ratios on feed intake (FI), performance, and processing yield. Experimental diets were formulated to 3,150 kcal/kg with 5 levels of digestible lysine (dLys)—80, 90, 100, 110, and 120% of recommended AA level giving g dLys/Mcal values of 2.53, 2.85, 3.17, 3.48, and 3.80, respectively. All other AA were formulated to a fixed ratio to dLys. A total of 4,050 chicks were utilized in each trial (9 replicate pens for each AA level and each line; 45 chicks/pen) conducted twice: one in hot environmental temperature (HT) (24 h mean ∼85.3 °F; 80.9% RH) and another in cool environmental temperature (CT) (24 h mean ∼71.6 °F; 61.7% RH). Results showed that FI was not impacted by dietary AA levels in HT for both lines. Higher FI (P < 0.05) was observed in CT for lower dietary AA levels (<100% AA level) for both lines, with overall higher FI occurring in Line B. Higher FI for Line B was also accompanied by higher body weight in HT and CT. Treatment diets had quadratic effects on average daily gain (ADG), feed conversion ratio (FCR), and processing yields (breasts and tenders) in both HT and CT, with broilers in CT performing better (P < 0.05). The optimal response values for ADG in HT and CT were 89.72 g and 113.44 g occurring at 120 and 109.5% AA level, respectively. The optimal response values for FCR in HT and CT were 1.79 and 1.58 occurring at 120 and 117.5% AA level, respectively. The optimal response values for breast meat yield in HT and CT were 575.9 g and 776.5 g occurring at 112.6 and 114.5% AA level, respectively. The optimal response values for tender meat yield in HT and CT were 119.8 g and 154.9 g occurring at 120 and 115% AA level, respectively. Line A had a higher breast and tender yield % (of live weight) for both environmental temperatures which correlated to body composition data with higher % protein mass and % digestible AA retention. In this study, findings indicated that effects of increased digestible AA density on FI, performance, and processing yield are specific to strain and grow-out temperature, but the optimum response was attained for both lines with diets containing 110 to 120% AA levels (3.48–3.80 g dLys/Mcal) during the 22 to 42 d finisher period.

Effects of reducing dietary amino acid density and stocking density on growth performance, carcass characteristics, meat quality, and occurrence of white striping in broiler chickens

A 49-day trial was conducted to determine the impact of dietary amino acid (AA) density and stocking density (SD) on growth performance, carcass traits, meat quality, and white striping (WS) occurrence in broiler chickens. Two hundred eighty-eight Ross 308 male broilers consisting of 6 replicate cages with 8 broilers per replicate were used. Treatments were arranged in a 3 × 2 factorial and consisted of 3 AA densities (normal, 10, or 20% lower than normal) and 2 different SD (high 35 kg/m² or low 26 kg/m²). Breasts were classified as normal, moderate, and severe for WS. Data were analyzed as a completely randomized design using the GLM procedure. Decreasing AA density decreased overall growth performance, carcass, breast yields, and fillet dimensions linearly, while leg and rib cage yields increased linearly (P < 0.01). High SD decreased hot carcass, breast, wings, and rib cage weights in birds fed normal AA diets (P < 0.05). High SD increased the length of breast fillet (P < 0.05). Cooking loss, breast lightness (L∗), and redness (a∗) at 48 h postmortem increased linearly with decreasing AA density, while ultimate breast pH (pH_u) and nitrogen content decreased linearly (P < 0.05). The occurrence of normal, moderate, and severe WS fillets was 45.3, 49.1, and 5.6%, respectively. As the dietary AA density decreased, the occurrence of no WS breast fillets increased linearly, whereas the occurrence of moderate WS fillets and mean WS score decreased linearly (P < 0.05). SD did not affect the occurrence of WS. Severe WS fillets were heavier and had higher cranial thickness, pH_u, and fat content and lower yellowness (P < 0.05), but water-holding capacity, nitrogen content, L∗, and a∗ value did not differ among different WS scores. Taken together, WS occurrence and severity increased with higher growth rate. Growth depression created by lowering dietary AA density regardless of SD resulted in a decrease in mean WS score, but it also compromised the growth and meat quality.

Amino acid transportation, sensing and signal transduction in the mammary gland: key molecular signalling pathways in the regulation of milk synthesis

The mammary gland, a unique exocrine organ, is responsible for milk synthesis in mammals. Neonatal growth and health are predominantly determined by quality and quantity of milk production. Amino acids are crucial maternal nutrients that are the building blocks for milk protein and are potential energy sources for neonates. Recent advances made regarding the mammary gland further demonstrate that some functional amino acids also regulate milk protein and fat synthesis through distinct intracellular and extracellular pathways. In the present study, we discuss recent advances in the role of amino acids (especially branched-chain amino acids, methionine, arginine and lysine) in the regulation of milk synthesis. The present review also addresses the crucial questions of how amino acids are transported, sensed and transduced in the mammary gland.

Modelling Methionine Requirements of Fast- and Slow-Growing Chinese Yellow-Feathered Chickens during the Starter Phase

Simple Summary

In poultry production, consuming diets with low or excessive methionine levels leads to negative effects on growth performance. The requirements of methionine may differ among the fast and slow-growing breeds; therefore, the optimal dietary methionine level should be estimated for each. In this study, six dietary methionine levels were evaluated to estimate the optimal level for fast and slow-growing yellow feathered chicken breeds. The quadratic polynomial and exponential asymptotic regression showed that the optimal methionine requirements for maximal growth performance were 0.50% and 0.53% in the fast-growing breed, and 0.48% and 0.52% in the slow growing breed.

Abstract

Two experiments were carried out to investigate the dietary methionine requirement for fast and slow-growing Chinese yellow-feathered breeds during the starter phase, based on growth variables and regression models. In Experiment 1, a total of 2880 one-day-old Lingnan chicks (fast growing breed) were used to test the methionine requirement from 1 to 21 days of age for males and females separately. Of each gender, 1440 birds were allocated into 6 dietary methionine levels (0.28%, 0.32%, 0.37%, 0.43%, 0.50% and 0.63%), each with 6 pen replicates of 40 chicks. Experiment 2 had the same design with Guangxi chicks (slow growing breed) from 1 to 30 d of age. Results indicated that significant nonlinear or quadratic responses to increasing dietary methionine levels were observed in body weight, daily gain, feed intake and feed conversion ratio of both breeds. In summary, the quadratic polynomial regression showed that the optimal methionine requirements for maximal growth performance of Lingnan chickens were 0.52–0.58% in males, 0.51% in females, and 0.53% in mixed genders. The corresponding values for Guangxi breed were 0.53% in males by quadratic polynomial regression and 0.43% in females, and 0.48% to 0.49% in mixed sexes by exponential asymptotic models.

Dietary methionine restriction regulated energy and protein homeostasis by improving thyroid function in high fat diet mice

Methionine-restricted diets (MRD) show an integrated series of beneficial health effects, including improving insulin sensitivity, limiting fat deposition, and decreasing oxidative stress, and inflammation responses. We aimed to explore the systemic responses to a MRD in mice fed with a high fat (HFD) and clarify the possible mechanism. Mice were fed with a control diet (0.86% methionine + 4% fat, CON), HFD (0.86% methionine + 20% fat), or MRD (0.17% methionine + 20% fat) for 22 consecutive weeks. HFD-fed mice showed widespread systemic metabolic disorders and thyroid dysfunction. A MRD significantly increased energy expenditure (e.g. fatty acid oxidation, glycolysis, and tricarboxylic acid cycle metabolism), regulated protein homeostasis, improved gut microbiota functions, prevented thyroid dysfunction, increased plasma thyroxine and triiodothyronine levels, decreased plasma thyroid stimulating hormone levels, increased type 2 deiodinase (DIO2) activity, and up-regulated mRNA and protein expression levels of DIO2 and thyroid hormone receptor α1 in the skeletal muscle. These results suggest that a MRD can improve the metabolic disorders induced by a HFD, and especially regulate energy and protein homeostasis likely through improved thyroid function. Thus, reducing methionine intake (e.g. through a vegan diet) may improve metabolic health in animals and humans.

Effects of dietary methionine on growth performance, meat quality and oxidative status of breast muscle in fast- and slow-growing broilers

This experiment was conducted to investigate the effects of dietary methionine (Met) on growth performance, carcass traits, meat quality and oxidative status of breast muscle in fast- (Arbor Acres, AA) and slow- (Partridge Shank, PS) growing broilers from 1 to 42 d of age. The broilers were divided into a 2 × 3 factorial design with 6 replicates per treatment. Diets were formulated to contain low (LM, 0.35 and 0.31% during 1 to 21 and 22 to 42 d), adequate (AM, 0.50 and 0.44%) and high (HM, 0.65 and 0.57%) Met, respectively. The main effects showed that the AA broilers had superior (P < 0.05) growth performance and carcass traits compared with those of the PS broilers. The breast muscle of the AA broilers had lower (P < 0.05) drip loss and malondialdehyde (MDA) content but higher (P < 0.05) cooking loss and glutathione peroxidase (GPX) activity than that of the PS broilers. Compared with the LM diets, the AM and HM diets increased (P < 0.05) 42-d BW, ADG, eviscerated yield and breast muscle yield only in the AA broilers. The AA broilers fed the HM diets had higher (P < 0.05) pH but lower (P < 0.05) L*, cooking loss and ether extract content in breast muscle than those fed the LM diets. Compared with the LM diets, the HM diets resulted in strain-dependent changes (P < 0.05) in muscle oxidative status, with total antioxidant capacity (T-AOC) increased in the AA broilers, GPX activity increased and MDA content decreased in the PS broilers, and superoxide dismutase (SOD) activity increased in both strains of broilers. No differences were observed between the AM and HM diets except for T-AOC in breast muscle. In conclusion, the LM treatment negatively affected broiler growth performance, carcass traits, meat quality and oxidative status of breast muscle in a strain-dependent manner, particularly in the AA broilers, whereas the HM treatment had limited effects compared to the AM treatment.

Effects of dietary supplementation with fermented and non-fermented brown algae by-products on laying performance, egg quality, and blood profile in laying hens

Objective

This study was conducted to investigate the effects of dietary supplementation with fermented and non-fermented brown algae by-products on the laying performance, egg quality, relative organ weight, and blood profile of laying hens.

Methods

Hy-Line Brown chickens (n = 180; 70-week-old) were randomly divided into 5 groups with 4 replicates per group (3 hens per cage, 4 cages per replicate), and fed with 5 experimental diets, namely the basal control diet (CON) or the control diet supplemented with 0.5% brown seaweed (BS), 0.5% seaweed fusiforme (SF), 0.5% fermented brown seaweed (FBS), or 0.5% fermented seaweed fusiforme (FSF), for 4 weeks.

Results

Egg production rate and egg mass were greater in the BS group than in the other groups (p<0.05), and the SF and FSF groups had greater egg production than the control group (p<0.05). Egg weight was higher in the BS group than in the other groups (p<0.05). There were no differences in eggshell color, egg yolk color, eggshell strength, or eggshell thickness among the groups. There was no difference in Haugh units among the treatment groups, except for the FSF group, which had a significantly lower value (p<0.05). The non-fermented groups had greater relative organ weights, particularly the liver and cecum, than the other groups (p<0.05). Regarding blood profile, the supplemented-diet groups had higher albumin levels than the control group (p<0.05). The FBS group had higher total cholesterol and triglyceride levels than the other groups (p<0.05). The BS and FBS groups had higher glutamic pyruvic transaminase levels than the other groups (p<0.05).

Conclusion

This study demonstrated that dietary brown algae supplementation can improve egg-laying performance; however, supplementation with fermented seaweeds had no positive effect on the egg-laying performance of hens.

Effects of dietary methionine on productivity, reproductive performance, antioxidant capacity, ovalbumin and antioxidant-related gene expression in laying duck breeders

The study investigated whether dietary methionine (Met) affects egg weight and antioxidant status through regulating gene expression of ovalbumin (OVAL), nuclear factor erythroid 2 like 2 (Nrf2) and haem oxygenase 1 (HO-1) in laying duck breeders. Longyan duck breeders (n 540, 19 weeks) were randomly assigned to six treatments with six replicates of fifteen birds each. Breeders were fed diets with six Met levels (2·00, 2·75, 3·50, 4·25, 5·00 and 5·75 g/kg) for 24 weeks. The egg weight (g), egg mass (g/d), feed conversion ratio, hatchability, 1-d duckling weight, albumen weight, albumen proportion and OVAL mRNA level improved with dietary Met levels, whereas yolk proportion decreased (P<0·05). The weight of total large yellow follicles increased linearly (P<0·001) and quadratically (P<0·05) with dietary Met concentration, and their weight relative to ovarian weight showed a linear (P<0·05) effect. Dietary Met level had a linear (P<0·05) and quadratic (P<0·001) effect on the gene expression of glutathione peroxidase (GPX1), HO-1 and Nrf2, and quadratically (P<0·05) increased contents of GPX and total antioxidant capacity (T-AOC) in liver of duck breeders. In addition, maternal dietary Met enhanced gene expression of GPX1, HO-1 and Nrf2, increased contents of GPX and T-AOC and reduced carbonylated protein in the brains of hatchlings. Overall, dietary Met concentration affected egg weight and albumen weight in laying duck breeders, which was partly due to gene expression of OVAL in oviduct magnum. A diet containing 4·0 g Met/kg would achieve optimal hepatic GPX1 and Nrf2 expression, maximise the activity of GPX and minimise lipid peroxidation.

Marginal deficiencies of dietary arginine and methionine could suppress growth performance and immunological responses in broiler chickens

The present study was conducted to investigate the effects of different levels of dietary arginine (Arg) and methionine (Met) on performance, immune responses, and carcass characteristics of broiler chickens. A total of 540 day-old Ross 308 broiler chicks were randomly assigned into the nine experimental diets, consisting five replicates of 12 birds each. Dietary treatments included three different levels (90%, 100%, and 110% of National Research Council [NRC] specifications) of either dietary Arg or Met, which were fed to the birds according to a 3 × 3 factorial arrangement of treatments during a 42 days feeding trial. Results showed that supplementation of Arg and Met into the deficient-diets increased (p < .01) weight gains during all trial periods. Although average daily feed intake (ADFI) was not influenced by dietary treatments, increasing Arg up to 100% of NRC recommendations improved (p < .05) feed conversion ratio (FCR) throughout the trial period. Similarly, supplementation of deficient-diets with Met improved FCR values. There was a significant (p < .01) Arg × Met interaction for ADFI during the starter period; increasing the dietary Arg level increased ADFI when the diets were deficient in Met, while had an opposite effect in diets containing higher dietary Met levels. On the other hand, dietary Met fortification improved (p = .067) FCR values to a greater extent in 110% Arg-diets during the entire trial period. Although different levels of Arg and Met had no marked effects on carcass yield and abdominal fat percentage, supplemental Arg up to 100% of NRC values increased (p < .01) the relative weights of spleen and bursa of Fabricius. Furthermore, bursa weight was affected by Arg × Met interaction (p < .01), so that supplemental Arg level of 100% of NRC increased the relative bursa weight in birds that were fed diets containing 90% and 110% of Met. Serum uric acid level was decreased (p < .05) as a result of dietary Arg fortification up to 110% of NRC recommended values. Supplementation of deficient-diets with Met decreased (p < .05) serum cholesterol level. Although Newcastle antibody titer was not affected by dietary Arg or Met levels, Arg fortification of deficient-diets increased (p < .001) antibody responses against infectious bronchitis (IBV) and bursal (IBD) disease viruses. Similarly, Met supplementation of deficient-diets increased IBD antibody titer. There were significant (p < .05) Arg × Met interactions for IBV and IBD titers; Met fortification of 110% Arg-diets was more effective in increasing antibody titers. An increase in dietary Met level up to 100% of NRC values increased (p < .001) serum concentration of γ-globulins. The present findings imply that supplemental Arg could affect feed efficiency and antibody responses when the diets were already fortified with a sufficient Met level.

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.

High-Methionine Diet Attenuates Severity of Arthritis and Modulates IGF-I Related Gene Expressions in an Adjuvant Arthritis Rats Model

Rheumatoid arthritis, a synthesized form of adjuvant arthritis exhibited throughout many animal species, inhibits liver function and circulation of IGF-I and contributes to the degradation of skeletal muscle mass. One of the primary goals of the present study is determining whether a high-Methionine (high-Met) diet is capable of reducing the adverse effects of arthritis, namely, loss of body mass. Following adjuvant injection, forty arthritic rats were randomly assigned to either a control group with a basal diet or a high-Met group with the same basal diet + 0.5% Methionine. After 14 days all rats were terminated. The high-Met group exhibited an increase in body weight and food intake in comparison with the control group (P < 0.05). High-Met diet debilitated arthritis-induced surges in the gastrocnemius in both atrogin-1 and the MuRF1 expressions; however, it was observed to have little to no effect on atrogin-1 and MuRF1 gene expression in soleus. At the same time, high-Met diet rats experienced a rise in IGF-I, with lowering of IGFBP-3 gene expression in the gastrocnemius and the soleus. These data suggest that arthritis severity can be partly attenuated by high-Met diet.

Circulating levels of insulin-like growth factor-1 and associated binding proteins in plasma and mRNA expression in tissues of growing pigs on a low threonine diet

The aim was to determine whether dietary threonine levels affected hepatic insulin-like growth factor-1 (IGF-1) mRNA expression as well as plasma IGF-1 concentration and IGF binding protein (IGFBP) profile in growing pigs. Two male 6-week-old pigs from each of seven litters were used. Each littermate was assigned to one of two diets, control or low threonine (LT), providing per kg 14·3 MJ digestible energy in both diets, 170 g protein in the control diet and 167 g protein in the LT diet. The control diet contained all essential amino acids in the recommended amounts, including 8·2 g threonine per kg. The LT diet was similar but contained only 5·1 g threonine per kg. Pigs were pair-fed these diets for 3 weeks. Growth rate and food efficiency of pigs given the LT diet were significantly lower than those of pigs given the control diet (P 0·001). Plasma IGF-1 concentration of pigs given the LT diet was proportionately 0·44 lower than that of pigs given the control diet (P 0·01). Plasma free threonine concentration of pigs given the LT diet was lower than that of the pigs given the control diet (P 0·001). Plasma IGFBP2 level of pigs given the LT diet was significantly higher than that of pigs given the control diet (P 0·05). Pigs given the LT diet had a significantly lower plasma IGFBP3 level compared with their littermates given the control diet (P 0·05) suggesting that clearance rate of circulating IGF-1 was higher in the LT group. Dietary threonine level did not affect IGF-1 mRNA abundance in the liver. It is concluded that lower plasma IGF-1 level caused by reduced dietary threonine level may have been partly due to increased clearance rate of circulating IGF-1 but not due to IGF-1 gene expression in the liver.

Methionine deficiency leads to hepatic fat accretion via impairment of fatty acid import by carnitine palmitoyltransferase I

1. To clarify the underlying mechanism of hepatic fat accretion due to methionine (Met) deficiency in broiler chickens, the present study investigated the effect of Met deficiency on the hepatic carnitine palmitoyltransferase (CPT) system, which imports fatty acids into mitochondria. 2. Fifteen-d-old male meat-type chickens were fed on either a control diet (containing 0.52 g/100 g Met) or a Met-deficient diet (containing 0.27 g Met/100 g). After a 10-d feeding period, the birds were killed by decapitation and their livers excised to determine hepatic CPT1 and CPT2 mRNA levels and for the related hepatic fatty acid-supported mitochondrial respiration to be measured. 3. Met deficiency decreased body weight gain and feed efficiency and increased hepatic lipid content compared to the control group. Whereas the hepatic CPT2 mRNA level in the Met-deficient group remained unchanged compared to that of the control group, the CPT1 mRNA level was decreased in the Met-deficient group and CPT1-dependent hepatic mitochondrial respiration was impaired. 4. Our results suggest that the hepatic lipid accretion that occurs in response to Met deficiency might be attributable to the impairment of CPT1-mediated fatty acid import into mitochondria.

Thermal stress induces changes in gene expression and blood parameters in high and low feed efficiency meat quail

In this study, we analysed markers of stress, plasma creatinine and T3 content, and insulin-like growth factor I (IGF-I), growth hormone receptor (GHR), uncoupling protein (UCP), adenine nucleotide translocase (ANT) and cytochrome c oxidase subunit III (COX III) mRNA expression in the liver and muscle of high (0.22 g/g) and low (0.14 g/g) feed efficiency (FE) meat quail at three different air temperatures, comfortable, heat and cold stress, for 24 h. High FE quail presented higher plasma T3 and lower creatinine levels. IGF-I mRNA expression was higher in the livers of high FE quail than in the livers of low FE quail under both comfortable and cold stress conditions. In the muscle, regardless of the environment, high FE birds showed higher IGF-I mRNA expression. High FE birds also showed higher GHR mRNA expression under comfortable conditions. Regarding the environment, higher expression was observed in birds at comfortable conditions, and lower expression in birds under heat stress. UCP mRNA expression in the liver was lower in high FE birds and higher under heat stress compared with the other conditions. Low and high FE birds showed greater ANT mRNA expression in the muscle under cold stress. Greater mRNA COX III expressions were observed in the liver and muscle of quails under comfortable conditions. Our results suggest that temperature affects the expression of genes related to growth and mitochondrial energy production, and quail with different FEs respond differently to environmental stimuli. In comfortable conditions, high FE animals show higher IGF-I mRNA expression and plasma T3 and lower creatinine content.

Methionine improves the performance and breast muscle growth of broilers with lower hatching weight by altering the expression of genes associated with the insulin-like growth factor-I signalling pathway

The present study aimed to investigate the responses of broilers with different hatching weights (HW) to dietary methionine (Met). A total of 192 1-d-old Arbor Acres broiler chicks with different HW (heavy: 48·3 (sem 0·1) g and light: 41·7 (sem 0·1) g) were allocated to a 2 (HW) × 2 (Met) factorial arrangement with six replicates of eight chicks. Control starter (1-21 d) and finisher (22-42 d) diets contained 0·50 and 0·43 % Met, respectively. Corresponding values for a high-Met treatment were 0·60 and 0·53 %. Light chicks had poorer (P< 0·05) growth performance and breast muscle weight and lower (P< 0·05) insulin-like growth factor-I (IGF-I) concentration and mRNA level in breast muscle than heavy chicks when both were fed the control diets. High-Met diets improved performance and promoted breast muscle growth and IGF-I concentration in light chicks (P< 0·05). Increased IGF-I and target of rapamycin (TOR) mRNA levels as well as decreased eIF4E-binding protein 1 (4EBP1), atrogin-1 and forkhead box O 4 (FOXO4) mRNA levels were induced by high-Met diets in light chicks (P< 0·05). In conclusion, the Met requirement of broilers might depend on their HW and Met levels used in the control diets in the present study were adequate for heavy chicks but inadequate for light chicks, resulting in poorer performance and breast muscle growth, which were improved by increasing dietary Met supply presumably through alterations in IGF-I synthesis and gene expression of the TOR/4EBP1 and FOXO4/atrogin-1 pathway.

Pathology of bursae of Fabricius in methionine-deficient broiler chickens

The purpose of this 42-day study was to investigate the effects of methionine (Met) deficiency on immune function by determining the relative weight, morphological and ultrastructural changes of bursae of Fabricius, cell cycle, and apoptosis of bursa cells. One hundred and twenty one-day-old avian broilers were randomly divided into two groups and fed on a control diet (starter diet, Met 0.50%; grower diet, Met 0.40%) and Met-deficient diet (starter diet, Met 0.26%; grower diet, Met 0.28%) for six weeks. The relative weight of bursae was decreased with Met deficiency when compared to that of the control group. Lesions were also observed in the Met-deficient group. Histopathologically, the numbers of lymphocytes in the follicles were decreased. Ultrastructurally, the mitochondria of lymphocytes were swollen in the Met-deficient group. As measured by flow cytometry, bursal cells in the G₀G₁ phase were significantly higher (P < 0.01), and bursal cells in the S, G₂M phases and proliferating index were obviously lower (P < 0.01) with Met deficiency than in the control group. Moreover, the percentage of apoptotic cells in the bursae were significantly increased in Met-deficient birds (P < 0.01). It was concluded that Met deficiency restrained the development of the bursae of Fabricius and affected the humoral immunity of the chickens.

Expression of genes involved in the somatotropic, thyrotropic, and corticotropic axes during development of Langshan and Arbor Acres chickens

We investigated changes in mRNA expression of the somatotropic, thyrotropic, and corticotropic axes of Langshan (LS) and Arbor Acres (AA) broiler chickens during embryonic and postnatal development. We found an inverse expression profile between pituitary growth hormone (GH) and hepatic GH receptor mRNA [postnatal d (P)28 to P42], insulin-like growth factor (IGF)-I, and IGF-IR (P0 to P42), respectively. Hepatic IGF-I was a major point of control in the GH-IGF axis from P0 to P28. Pituitary GH-releasing hormone receptor may serve an autocrine-paracrine function from P0 to P28, and hypothalamic ghrelin may affect growth by stimulating the release of hepatic IGF-I from embryonic d (E)8 to P28. Hypothalamic ghrelin might interact with corticotropin-releasing hormone (CRH) from P0 to P28. Hepatic IGF-binding protein-2 regulated growth by regulating hepatic IGF-II bioavailability from P0 to P42. Hepatic IGF-binding protein-5 was an important IGF mediator. A coexpression profile was found between hypothalamic GH-releasing hormone (E10 to E16 and P0 to P42), somatostatin (SS; P0 to P28), thyrotropin-releasing hormone (E10 to E16 and P0 to P28), ghrelin (P0 to P42), and pituitary GH mRNA, hypothalamic SS (P0 to P28), corticotropin-releasing hormone (P0 to P42), thyrotropin-releasing hormone (E10 to E18 and P0-P42), and thyroid-stimulating hormone-beta mRNA, respectively. Moreover, AA chickens were fed a nutrient-rich AA diet (as a control group) and LS chickens were fed either a less nutritious LS diet or the AA diet. Langshan and AA chickens fed the same AA diet showed no differences in pituitary GH, hypothalamic SS, ghrelin, hepatic IGF-I, or GH receptor mRNA. Our data indicate that select genes may show parallel expression during certain periods of development, and that differences in BW and gene expression respond differently to nutrient intake in LS and AA chickens. Our findings may help improve the molecular breeding of chickens.

Effects of lysine deficiencies on plasma levels of thyroid hormones, insulin-like growth factors I and II, liver and body weights, and feed intake in growing chickens

Adequate (1.10%) and deficient (0.88, 0.66, and 0.53%) levels of Lys were fed to broiler chicks from 9 to 23 d of age. Groups fed the control diet (1.10% Lys) were also pair-fed daily with each deficient group. Compared with the free-fed control, graded decreases in feed intake occurred as the deficiency worsened, and these were significantly different with 0.66 and 0.53% Lys. Growth decreased significantly with each deficient level of Lys compared with the free-fed control and was always significantly lower than in the pair-fed control groups in each set. Plasma triiodothyronine (T3) was elevated in chicks fed 0.88 and 0.66% lysine but not with 0.53% when compared with the full-fed control treatment. However, in deficient chicks receiving 0.66 and 0.53% Lys, T3 levels were significantly higher compared with their pair-fed controls. Plasma T4 was not significantly different between any treatments. Liver weights decreased significantly at each level of Lys deficiency, but most of the differences disappeared when expressed relative to body weight. Plasma insulin-like growth factor (IGF)-I decreased significantly with the most severe Lys deficiency. However, it decreased to a similar degree in the pair-fed controls, showing that this effect was primarily due to the lower feed intake. Plasma IGF-II levels did not differ between any treatments. No correlations were evident between thyroid hormones and IGF-I or IGF-II values. We concluded that the primary effect of Lys deficiency was an elevation in plasma T3 levels without accompanying changes in plasma T4. No effect of the Lys deficiency per se on plasma IGF-I and IGF-II and liver weights relative to body weights was found.

Optical quality changes of the ocular lens during induced parr-to-smolt metamorphosis in Rainbow Trout (Oncorhynchus mykiss). Ocular lens optical quality during induced salmonid metamorphosis

The effect of an induced salmonid parr-to-smolt metamorphosis ('smoltification') on the optical quality of the ocular lens was studied. In two separate experiments, rainbow trout (Oncorhynchus mykiss) parr were fed thyroxine in their diet to induce the metamorphosis. Lenses were excised at regular samplings during the treatment period and optically scanned using a custom scanning laser monitor. Radioimmunoassay was used to measure serum titers of thyroxine and 3,5,3'-triiodo-L: -thyronine. It was found that lens optical quality was consistently negatively correlated with 3,5,3'-triiodo-L: -thyronine levels, but not with thyroxine levels. To test if thyroid hormones are directly responsible for the change in optical quality, rainbow trout lenses were cultured for 72 h in a medium containing 3,5,3'-triiodo-L: -thyronine, but no effect was observed. The significance of these findings in the contexts of the fishes' visual capabilities and smolting physiology is discussed.