The amino acid composition of tissue protein is affected by the total sulfur amino acid supply in growing pigs

An Estimation of the Requirements of the Standardized Ileal Digestible Tryptophan, Valine, Isoleucine and Methionine on Young Pigs' (Up to 50 kg) Feed Efficiency: A Meta-Regression Analysis

Currently, the NRC amino acid (AA) requirements for pigs published in 2012 are used as a reference in variable swine industries. However, recent results in several articles suggest that the standardized ileal digestible (SID) AA-lysine (Lys) ratio significantly evolved over the last two decades, while some publications report inconsistent outcomes. Therefore, the present study used a meta-regression analysis to assess the relative ratio to lysine to maximize the feed efficiency of four essential amino acids (tryptophan, valine, isoleucine, and methionine) in pig diets. According to the PRISMA guidelines, articles examining the target AA requirement using a basal diet supplemented with varying levels of crystalline AA (tryptophan, valine, isoleucine, or methionine) were identified across Scopus, PubMed, and Science Direct. As a result, 23, 22, 16, and 9 articles using tryptophan, valine, isoleucine, and methionine were selected and categorized into experiments for inclusion in our meta-analysis. The results suggested that the requirements of tryptophan, valine, isoleucine, and methionine in our meta-regression analysis were superior to NRC recommendations, regardless of the regression models and the growth phases with significant RSQ values (RSQ ≈ 1). Also, the QUAD and CLP regression models emphasized higher requirements than the LP model for the great majority of amino acids and growth phases. The results of the QUAD and CLP models were selected as estimations of the amino acid requirements for pigs under challenged conditions, whereas the LP model was chosen to estimate the amino acid requirements of genetically improved pigs under a modern housing system. The results of this meta-regression analysis could be used to refresh the information on the NRC amino acids (AA) requirements for swine.

Increased Sulphur Amino Acids Consumption as OH-Methionine or DL-Methionine Improves Growth Performance and Carcass Traits of Growing-Finishing Pigs Fed under Hot Conditions

This study aimed to evaluate the impact of DL-Methionine (DL-Met) or OH-Methionine (OH-Met) when supplemented beyond the usually accepted requirements in sulfur amino acids (SAA) on the performance and carcass traits of growing-finishing pigs. Two hundred mixed sex pigs were distributed in a randomized block (body weight and sex), under a 2 × 2 factorial design with two methionine sources, DL-methionine, or OH-Methionine and two methionine doses (100% SAA or 120% of the SAA level present in the control). Diets were formulated to meet amino acids recommendations of the Brazilian Tables for Poultry and Swine (2017), except for SAA, which varied with the methionine doses. Daily feed intake, daily weight gain, and feed conversion were evaluated. Moreover, the carcasses were measured electronically for fat thickness (FT), longissimus dorsi muscle depth (LD), and lean meat (%). During the growing phase II (92 till 122 days of age), daily feed intake (p < 0.001) and daily weight gain (p < 0.05) increased with the high SAA levels. High SAA levels also provided greater daily weight gain during the entire period of the trial (0.90 versus 0.86 kg; p < 0.05) No significant interaction was observed between the methionine source and the SAA level for any carcass traits. However, animals that received OH-Met had greater (p < 0.05) loin depth (58.37 versus 55.21 mm) and those that received higher doses of methionine presented heavier (p < 0.05) carcass weight (78.16 versus 74.70 kg), and more (p < 0.05) lean meat weight (43.69 versus 41.90 kg). Taken together, these results demonstrated that supplementation of high sulfur amino acids levels under hot conditions provided heavier carcasses and more lean meat.

Feeding Strategies to Reduce Nutrient Losses and Improve the Sustainability of Growing Pigs

The efficiency of pig production using nutrients has increased over the years. Still, better efficiency of nutrient utilization can be achieved by feeding pigs with diets adjusted to their estimated requirements. An increase in nutrient efficiency of utilization represents economic gains while maximizing environmental performance. The objective of this paper is to review the impact of different methods of diet formulation that provide farm animals with the amount of nutrients to satisfy their needs while minimizing nutrient excretion and greenhouse gas emissions. Diet formulation is one tool that can help to maximize nitrogen and energy utilization by decreasing crude protein content in diets. The use of local feedstuff and non-human-edible products (e.g., canola meal) associated with synthetic amino acid inclusion in the diet are valuable techniques to reduce carbon footprint. Precision feeding and nutrition is another powerful tool that allows not only daily tailoring of diets for maximal nutrient efficiency of utilization but also to reduce costs and improve nitrogen efficiency of utilization. In this review, we simulated through mathematical models the nitrogen and energy efficiency of utilization resulting from crude protein reduction in the diet. An 8% crude protein reduction in the diet can increase nitrogen efficiency of utilization by 54% while costing 11% less than a control diet without synthetic amino acids. The same reduction in crude protein represented a major improvement in available energy due to the decrease of energetic losses linked to protein deamination. Urinary and hindgut fermentation energy losses were 24% lower for pigs fed with low-protein diets when compared to control diets. In terms of modern feeding techniques and strategies, precision feeding and nutrition can decrease nitrogen excretion by 30% when compared to group phase feeding. The benefits of feeding pigs with low-protein diets and precision feeding techniques are additive and might result in a 61% nitrogen efficiency of utilization. There is room for improvement in the way nutrient requirements are estimated in pigs. Improving the understanding of the variation of nutrient utilization among pigs can contribute to further environmental gains.

Flash dietary methionine supply over growth requirements in pigs: Multi-facetted effects on skeletal muscle metabolism

Dietary methionine affects protein metabolism, lean gain and growth performance and acts in the control of oxidative stress. When supplied in large excess relative to growth requirements in diets for pigs, positive effects on pork quality traits have been recently reported. This study aimed to decipher the molecular and biochemical mechanisms affected by a dietary methionine supply above growth requirements in the loin muscle of finishing pigs. During the last 14 days before slaughter, crossbred female pigs (n = 15 pigs/diet) were fed a diet supplemented with hydroxy-methionine (Met5; 1.1% of methionine) or not (CONT, 0.22% of methionine). Blood was sampled at slaughter to assess key metabolites. At the same time, free amino acid concentrations and expression or activity levels of genes involved in protein or energy metabolism were measured in the longissimus lumborum muscle (LM). The Met5 pigs exhibited a greater activity of creatine kinase in plasma when compared with CONT pigs. The concentrations of free methionine, alpha-aminobutyric acid, anserine, 3-methyl-histidine, lysine, and proline were greater in the LM of Met5 pigs than in CONT pigs. Expression levels of genes involved in protein synthesis, protein breakdown or autophagy were only scarcely affected by the diet. Among ubiquitin ligases, MURF1, a gene known to target creatine kinase and muscle contractile proteins, and OTUD1 coding for a deubiquitinase protease, were up-regulated in the LM of Met5 pigs. A lower activity of citrate synthase, a reduced expression level of ME1 acting in lipogenesis but a higher expression of PPARD regulating energy metabolism, were also observed in the LM of Met5 pigs compared with CONT pigs. Principal component analysis revealed that expression levels of many studied genes involved in protein and energy metabolism were correlated with meat quality traits across dietary treatments, suggesting that subtle modifications in expression of those genes had cumulative effects on the regulation of processes leading to the muscle transformation into meat. In conclusion, dietary methionine supplementation beyond nutritional requirements in pigs during the last days before slaughter modified the free amino acid profile in muscle and its redox capacities, and slightly affected molecular pathways related to protein breakdown and energy metabolism. These modifications were associated with benefits on pork quality traits.

AMPK-mTOR pathway is involved in glucose-modulated amino acid sensing and utilization in the mammary glands of lactating goats

Background

The local supply of energy-yielding nutrients such as glucose seems to affect the synthesis of milk components in the mammary gland (MG). Thus, our study was conducted to investigate the effects of locally available MG glucose supply (LMGS) on amino acid (AA) sensing and utilization in the MG of lactating dairy goats. Six dosages of glucose (0, 20, 40, 60, 80, and 100 g/d) were infused into the MG through the external pudendal artery to investigate the dose-dependent changes in mammary AA uptake and utilization (Exp.1) and the changes in mRNA and protein expression of the AMPK-mTOR pathway (Expt.2).

Results

In Exp.1, total milk AA concentration was highest when goats were infused with 60 g/d glucose, but lower when goats were infused with 0 and 100 g/d glucose. Increasing LMGS quadratically changed the percentages of α_S2-casein and α-lactalbumin in milk protein, which increased with infusions from 0 to 60 g/d glucose and then decreased with infusions between 60 and 100 g/d glucose. The LMGS changed the AA availability and intramammary gland AA utilization, as reflected by the mammary AA flux indexes. In Exp.2, the mRNA expression of LALBA in the MG increased quadratically with increasing LMGS, with the highest expression at dose of 60 g/d glucose. A high glucose dosage (100 g/d) activated the general control nonderepressible 2 kinase, an intracellular sensor of AA status, resulting in a reduced total milk AA concentration.

Conclusions

Our new findings suggest that the lactating MG in dairy goats may be affected by LMGS through regulation of the AA sensory pathway, AA utilization and protein synthesis, all being driven by the AMPK-mTOR pathway.

Genotype and dietary lysine deficiency affect carcass and muscle amino acid composition of pigs growing from 10 to 25 kg body weight

Amino acid (AA) composition of body protein is considered constant although there are evidences that AA pattern in pigs may be altered by different factors. Pigs with different body composition and protein deposition rates-like fatty and lean pigs-may differ in AA composition, with possible consequences on their AA requirements. This work investigates effects of genotype and dietary lysine deficiency on AA composition of carcass and muscles of Iberian and Landrace × Large White pigs. Twenty-eight barrows (10 kg body weight [BW]), 14 from each breed, were used. They were randomly assigned to two experimental diets according to a factorial arrangement (two breeds × two diets). Diets were isonitrogenous and isoenergetic (200 ± 1 g CP/kg dry matter (DM); 14.7 ± 0.1 MJ ME/kg DM) and with identical chemical composition except for lysine concentration (10.9 and 5.20 g lysine/kg DM, for lysine-adequate (AL) diet and lysine-deficient (DL) diet respectively). Pigs were individually housed, and daily feed allowance was adjusted on a weekly basis according to BW. Pigs were slaughtered at 25 kg BW. Isoleucine, valine and phenylalanine concentration were higher in carcass protein of Iberian pigs (p < .01). In longissimus muscle, higher concentration of arginine, isoleucine, phenylalanine, lysine and valine (p < .001-p < .05), and lower of methionine (p < .001) were detected in Iberian pigs, whereas phenylalanine, leucine, lysine, threonine and methionine concentration decreased and arginine increased (p < .001-p < .05) when pigs were fed DL diet. Genotype and lysine deficiency effects were moderate in the AA composition of protein of biceps femoris muscle. The results show that AA proportions in protein of carcass and longissimus muscle can be influenced by pig genotype and conditions of lysine shortage. The biceps femoris muscle, with different functional and metabolic properties, shows more constant AA composition than longissimus, which seem to prevail independent from genotype or nutritional challenges.

Effects of lysine deficiency on carcass composition and activity and gene expression of lipogenic enzymes in muscles and backfat adipose tissue of fatty and lean piglets

The purpose of this study was to investigate potential mechanisms involved in fat deposition promoted by dietary lysine deficiency, particularly intramuscular fat (IMF), and differential responses between fatty and lean pigs. Carcass traits and lipogenic enzyme activities and gene expression levels in muscles and adipose tissue were investigated in Iberian (fatty) and Landrace × Large White (LDW) pigs under identical feeding level (based on body weight (BW)) and management conditions. Twenty-eight barrows of 10 kg initial BW, 14 per breed, were fed two isoproteic (200 g CP /kg DM) and isocaloric (14.7 MJ metabolizable energy/kg DM) diets with identical composition except for the lysine content (1.09% for diet adequate in lysine and 0.52% for diet deficient in lysine). At a BW of 25 kg, pigs were slaughtered. Compared with pigs fed the lysine-adequate diet, in both genotypes lysine-deficient diet led to lower carcass protein concentration, lower relative proportions of leaner components (loin, ham and shoulder; P < 0.01), and higher carcass fatty components and carcass lipid concentration (P < 0.001). Irrespective of diet, the activity and gene expression of lipogenic enzymes (fatty acid synthase (FAS), malic enzyme (ME) and glucose-6-phosphate dehydrogenase (G6PDH)) were greater in Iberian than in LDW pigs, particularly in adipose tissue where transcriptional regulators involved in the control of adipogenesis and lipogenesis were also upregulated in Iberian animals. In backfat tissue, there was a small decrease induced by or no effects of lysine-deficient diet on the activity and gene expression of lipogenic enzymes, nor in gene expression levels of upstream regulators of lipogenesis and adipogenesis. In longissimus muscle, the activity of FAS, G6PDH and ME increased with lysine deficiency in both genotypes (P < 0.01) and an upregulation of gene expression of lipogenic enzymes was specifically observed in Iberian pigs (P < 0.05 to P < 0.001). In biceps femoris muscle of lysine-deficient pigs, the activity of FAS and ME enzymes increased, ME1 gene was upregulated (added to FASN gene in the case of Iberian pigs; P < 0.01 to P < 0.001) and PPARA gene was downregulated (P < 0.05). The results show that in both fatty and lean pigs, the effect of lysine deficiency on lipid metabolism was tissue-specific, with an activation of lipogenesis in longissimus and biceps femoris muscle but no apparent stimulation in backfat adipose tissue. Suitable feeding protocols including lysine-deficient diets should be designed for each pig type in order to increase intramuscular lipids without penalizing the growth of lean carcass components.

Endogenous Amino Acid Losses from the Gastrointestinal Tract of the Adult Human-A Quantitative Model

Background

The loss of endogenous (nondietary) amino acids (AAs) from the gastrointestinal tract (GIT) is an important component underlying the adult human dietary requirement for protein and essential AAs (EAAs). Although data with regard to endogenous AA losses to the end of the small intestine have been published, to our knowledge there are no direct measures of colonic endogenous AA losses.

Objective

The objective was to derive quantitative estimates for daily endogenous protein and EAAs lost from the colon of the adult human.

Methods

A factorial model was developed for the prediction of endogenous AA losses across the adult human GIT. Estimates of AAs entering the upper GIT lumen were combined with relative protein synthesis rates in the colon to predict colonic AA losses. The AA composition of human colonic endogenous protein was calculated by estimating the relative contributions of epithelial cell protein and mucin protein on the basis of published data for cell shedding in the pig small intestine, small intestinal protein synthesis rates in pigs and humans, and human upper and lower GIT surface areas. Colonic AA losses were summed with empirical estimates of ileal AA losses in humans to estimate total daily GIT endogenous AA losses.

Results

Colonic AA loss was estimated to total 3.5 g/d in the adult male human, comprising 33% of total GIT endogenous AA loss (10.2 g/d). GIT essential AA losses accounted for 25-97% of the current recommended daily AA requirement for adult humans. For threonine, colonic losses were 54% of total GIT threonine losses, which were 97% of the current recommended daily threonine requirement.

Conclusions

Colonic endogenous AA losses represent a significant fraction of total GIT endogenous AA losses. The requirement of the GIT for EAAs to replace AAs lost via the gut lumen comprises a substantial proportion of the Recommended Daily Intake of AAs.

Dietary CP and amino acid restriction has a different impact on the dynamics of protein, amino acid and fat deposition in entire male, castrated and female pigs

Breeding efforts over the last decades altered markedly empty body (EB) composition of pigs. This study aimed to re-evaluate the dynamics of changes in the composition and deposition rate of fat, protein and amino acids (AA) in the EB from birth to 140 kg BW depending on the dietary CP and AA supply in a current pig genotype. In the experiment 66 entire male, 58 castrated and 66 female Swiss Large White pigs were used. From 20 kg BW onwards, they had either ad libitum access to a control (C) diet or a diet (LP) compared to diet C only 80% of CP, lysine, methione+cystine, threonine and tryptophan. The EB composition was determined at birth on eight boars and eight females, at 10 and 20 kg BW on two boars, two castrates and two females, and at 20 kg intervals from 40 to 140 kg BW, on four pigs per gender and dietary treatment. Each EB fraction was weighed and analysed for protein, fat and AA profile. The AA-to-lysine ratio was calculated and the different chemical component contents were fitted to allometric regressions. Overall, C-boars had the greatest EB protein and AA content and deposition rates, and lowest fat content and deposition rates. At the beginning of the grower period, LP-castrates and females displayed the lowest protein and AA and the highest fat deposition rates. However, compared with their counterparts in the C-group, in LP-castrates and females protein and AA deposition rates were greater above 64 and 40 kg EB weight, respectively, whereas fat deposition rates was lower above 80 kg EB weight. Thus, there seems a great potential to optimise protein and AA efficiency especially in the finisher period in castrates and females. Important individual variations were found in the essential AA-to-lysine ratio of the EB. Phenylalanine and threonine-to-lysine ratios decreased with increasing EB weight. Valine- and threonine-to-lysine ratios in C-castrates and C-females were 5% and 4% greater than recently reported by the National Research Council (NRC) whereas cysteine-, methionine- and tyrosine-to-lysine ratios were lower by 34%, 25% and 10%, respectively. The clear differences found between the EB AA-to-lysine ratios in the present study and the NRC might partly be explained by the genotype and the temporal changes in the relative weight of each EB fraction or changes in the AA profile. Nevertheless, these findings on changes in the essential AA profile of tissue protein warrant further studies.

Protein structural changes during processing of vegetable feed ingredients used in swine diets: implications for nutritional value

Protein structure influences the accessibility of enzymes for digestion. The proportion of intramolecular β-sheets in the secondary structure of native proteins has been related to a decrease in protein digestibility. Changes to proteins that can be considered positive (for example, denaturation and random coil formation) or negative (for example, aggregation and Maillard reactions) for protein digestibility can occur simultaneously during processing. The final result of these changes on digestibility seems to be a counterbalance of the occurrence of each phenomenon. Occurrence of each phenomenon depends on the conditions applied, but also on the source and type of the protein that is processed. The correlation between denaturation enthalpy after processing and protein digestibility seems to be dependent on the protein source. Heat seems to be the processing parameter with the largest influence on changes in the structure of proteins. The effect of moisture is usually limited to the simultaneous application of heat, but increasing level of moisture during processing usually increases structural changes in proteins. The effect of shear on protein structure is commonly studied using extrusion, although the multifactorial essence of this technology does not allow disentanglement of the separate effects of each processing parameter (for example, heat, shear, moisture). Although most of the available literature on the processing of feed ingredients reports effects on protein digestibility, the mechanisms that explain these effects are usually lacking. Clarifying these mechanisms could aid in the prediction of the nutritional consequences of processing conditions.

Splanchnic tissues respond differently when piglets are offered a diet 30 % deficient in total sulfur amino acid for 10 days

PURPOSE

A deficient total sulfur amino acid (TSAA) supply has been reported to differently affect the amino acid composition of tissues, but limited information is available about its effects on the morphology and metabolic properties of splanchnic tissues.

METHODS

The amino acid composition, protein metabolism, glutathione concentration of the liver, proximal and distal jejunum, ileum and kidneys, and intestinal architecture were compared in 42-day-old piglets pair-fed either a diet deficient (TSAA-; 28 % deficiency) or sufficient (TSAA+) in TSAA for 10 days.

RESULTS

The supply of TSAA had no effect on tissue weights, but influenced the amino acid composition in a tissue-dependent manner. Compared with animals receiving diet TSAA+, the concentrations of Met and Ser were higher in liver protein of TSAA- animals while the Cys concentration in protein was lower in the liver but higher in the distal jejunum. The TSAA supply had no effect on protein synthesis and proteolytic activities of tissues. Villus width and surface, and crypt surface were lower in the proximal jejunum of TSAA- versus TSAA+ pigs. Crypt surface in the ileum of TSAA- pigs was higher. Pigs receiving diet TSAA- had lower GSH and GSSG concentrations in the liver and proximal jejunum, but the GSH/GSSG ratio was decreased only in the liver.

CONCLUSIONS

A greater nutritional priority appears to be given to splanchnic tissues so that its growth and protein metabolism can be maintained when the TSAA supply is limiting. The amino acid composition, glutathione status, and intestinal mucosa architecture are affected in a tissue-dependent manner.