Valine requirement of nursery pigs

The biological functions and metabolic pathways of valine in swine

Valine is an essential amino acid and a type of branched-chain amino acid. Due to the involvement of branched-chain amino acids in various metabolic pathways, there has been a surge of interests in valine nutrition and its role in animal physiology. In pigs, the interactions between valine and other branched-chain amino acids or aromatic amino acids are complex. In this review, we delve into the interaction mechanism, metabolic pathways, and biological functions of valine. Appropriate valine supplementation not only enhances growth and reproductive performances, but also modulates gut microbiota and immune functions. Based on past observations and interpretations, we provide recommended feed levels of valine for weaned piglets, growing pigs, gilts, lactating sows, barrows and entire males. The summarized valine nutrient requirements for pigs at different stages offer valuable insights for future research and practical applications in animal husbandry.

The Linear-Logistic Model: A Novel Paradigm for Estimating Dietary Amino Acid Requirements

This study aimed to determine whether current methods for estimating AA requirements for animal health and welfare are sufficient. An exploratory data analysis (EDA) was conducted, which involved a review of assumptions underlying AA requirements research, a data mining approach to identify animal responses to dietary AA levels exceeding those for maximum protein retention, and a literature review to assess the physiological relevance of the linear-logistic model developed through the data mining approach. The results showed that AA dietary levels above those for maximum growth resulted in improvements in key physiological responses, and the linear-logistic model depicted the AA level at which growth and protein retention rates were maximized, along with key metabolic functions related to milk yield, litter size, immune response, intestinal permeability, and plasma AA concentrations. The results suggest that current methods based solely on growth and protein retention measurements are insufficient for optimizing key physiological responses associated with health, survival, and reproduction. The linear-logistic model could be used to estimate AA doses that optimize these responses and, potentially, survival rates.

Evaluation of branched-chain amino acid interactions in 10 to 20 kg nursery pigs using a central composite design

Two groups of 240 pigs (PIC 337 × 1050, PIC Genus, Hendersonville, TN) were used to investigate the interactions between leucine, isoleucine, and valine on the growth performance of approximately 10 to 20 kg nursery pigs. At weaning, pigs were placed into 40 pens with three barrows and three gilts per pen and fed a common diet for 3 wk. On day 21 postweaning, pens were randomly assigned to 1 of 15 dietary treatments in a central composite design. Diets were formulated to various levels of standardized ileal digestible (SID) Leu, Ile, and Val by supplementing L-Leu, L-Ile, and L-Val. Levels of the branched-chain amino acids, expressed as ratios to SID Lys, ranged from 98% to 180%, 46% to 64%, and 51% to 78% for Leu, Ile, and Val, respectively. Diets were formulated to be iso-Lys, isonitrogenous, and isocaloric. Pig weights and feed intake were measured for the 21-d experiment to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (G:F). Growth performance data were analyzed using the lm() function in R version 4.2.2 (R Core Team, 2022). The second-order polynomial model included the linear and quadratic effects of Leu, Ile, and Val, their three two-way interactions, and initial body weight. Pen was the experimental unit, and parameters were considered significant at P ≤ 0.10. A linear and quadratic effect of Val was observed for ADG and G:F (P < 0.001). There was an interaction between Leu and Ile for ADG (P = 0.069) and G:F (P = 0.032), where increasing Leu and decreasing Ile, and the inverse, improved ADG and G:F. However, growth and efficiency were negatively impacted as Leu and Ile increased in the diet. There was an interaction between Leu and Val for ADFI (P = 0.060), where Leu negatively impacted feed intake at low levels of Val but had little impact as Val increased above NRC (2012) recommendations. In conclusion, Val linearly and quadratically impacted ADG and G:F, regardless of Leu and Ile levels in the diet, while ADG and G:F were reduced with high levels of Leu and Ile, which was resolved as either Leu or Ile was reduced. Furthermore, ADFI was negatively impacted by increased Leu when Val was below NRC (2012) recommendations but was not affected by Leu at higher Val levels. Together, the results of this experiment emphasize the complexity of amino acid metabolism in nursery pigs and the importance of considering potential interactions among amino acids when conducting requirement studies.

The Diversity, Composition, and Metabolic Pathways of Archaea in Pigs

Simple Summary

Archaea is identified as the key link in the interaction between gut microbiota and host metabo-lism. Studies on human and mice have reported archaea, especially methanogenic archaea, makes an important impact on the energy harvesting capacity of the host by improving fermentation. But, in pigs, the metabolic potential of archaea at different production stages are still largely unknown. Herein, we re-analyzed 276 metagenomic samples to explore the diversity, composi-tion, and potential functions of archaea in pigs. The results showed significant regional variations in archaeal composition. Furthermore, the Metacyc pathway related to hydrogen consumption (METHANOGENESIS-PWY) was only observed in archaeal reads, and archaea may be involved in carbohydrate metabolism and de novo synthesis of some kinds of essential amino acid. Overall, metagenomic re-analysis revealed that the composition and functional potential of archaea in the swine gut and suggested that archaea may make an important function in pigs.

Abstract

Archaea are an essential class of gut microorganisms in humans and animals. Despite the substantial progress in gut microbiome research in the last decade, most studies have focused on bacteria, and little is known about archaea in mammals. In this study, we investigated the composition, diversity, and functional potential of gut archaeal communities in pigs by re-analyzing a published metagenomic dataset including a total of 276 fecal samples from three countries: China (n = 76), Denmark (n = 100), and France (n = 100). For alpha diversity (Shannon Index) of the archaeal communities, Chinese pigs were less diverse than Danish and French pigs (p < 0.001). Consistently, Chinese pigs also possessed different archaeal community structures from the other two groups based on the Bray–Curtis distance matrix. Methanobrevibacter was the most dominant archaeal genus in Chinese pigs (44.94%) and French pigs (15.41%), while Candidatus methanomethylophilus was the most predominant in Danish pigs (15.71%). At the species level, the relative abundance of Candidatus methanomethylophilus alvus, Natrialbaceae archaeon XQ INN 246, and Methanobrevibacter gottschalkii were greatest in Danish, French, and Chinese pigs with a relative abundance of 14.32, 11.67, and 16.28%, respectively. In terms of metabolic potential, the top three pathways in the archaeal communities included the MetaCyc pathway related to the biosynthesis of L-valine, L-isoleucine, and isobutanol. Interestingly, the pathway related to hydrogen consumption (METHANOGENESIS-PWY) was only observed in archaeal reads, while the pathways participating in hydrogen production (FERMENTATION-PWY and PWY4LZ-257) were only detected in bacterial reads. Archaeal communities also possessed CAZyme gene families, with the top five being AA3, GH43, GT2, AA6, and CE9. In terms of antibiotic resistance genes (ARGs), the class of multidrug resistance was the most abundant ARG, accounting for 87.41% of archaeal ARG hits. Our study reveals the diverse composition and metabolic functions of archaea in pigs, suggesting that archaea might play important roles in swine nutrition and metabolism.

Meta-regression analysis to predict the influence of branched-chain and large neutral amino acids on growth performance of pigs1

A meta-analysis was conducted to evaluate the effects of branched-chain amino acids (BCAA), their interactions, and interactions with large neutral amino acids (LNAA) to develop prediction equations for growth performance of pigs. Data from 25 papers, published from 1995 to 2018, for a total of 44 trials and 210 observations were recorded in a database. Diets were reformulated using the NRC (2012) loading values to estimate nutrient concentrations. The response variables were average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F). The predictor variables tested included average body weight (BW), crude protein, neutral detergent fiber, Ile:Lys, Leu:Lys, Val:Lys, BCAA:Lys, Ile:Leu, Val:Leu, Ile:Val, (Ile+Val):Leu, Trp:Lys, Leu:Trp, Ile:Trp, Val:Trp, BCAA:Trp, Met:Lys, Leu:Met, Ile:Met, Val:Met, BCAA:Met, His:Lys, Leu:His, Ile:His, Val:His, BCAA:His, Thr:Lys, Leu:Thr, Ile:Thr, Val:Thr, BCAA:Thr, (Phe+Tyr):Lys, Leu:(Phe+Tyr), Ile:(Phe+Tyr), Val:(Phe+Tyr), BCAA:(Phe+Tyr), LNAA:Lys, Leu:LNAA, Ile:LNAA, Val:LNAA, and BCAA:LNAA. Amino acids were expressed on standardized ileal digestible basis. The MIXED procedure of SAS (SAS Institute Inc., Cary, NC) was used to develop the equations. The inverse of squared SEM was used to account for heterogeneous errors using the WEIGHT statement. Models were selected with a step-wise manual forward selection. In order to be included in the final model, predictor variables had to be statistically significant (P < 0.05) and provide an improvement of at least 2 points in Bayesian information criterion. The optimum equations were: ADG, g = - 985.94 + (15.2499 × average BW (kg)) - (0.08885 × average BW × average BW) + (1.063 × Leu:Lys) + (20.2659 × Ile:Lys) - (0.1479 × Ile:Lys × Ile:Lys) + (9.2243 × (Ile+Val):Leu) - (0.03321 × (Ile+Val):Leu × (Ile+Val):Leu) - (0.4413 × Ile:Trp); G:F, g/kg = 648.3 - (6.2974 × average BW (kg)) + (0.02051 × average BW × average BW) + (0.5396 × Ile:Lys) + (1.7284 × Val:Lys) - (0.00795 × Val:Lys × Val:Lys) - (1.7594 × Met:Lys); and ADFI, kg = predicted ADG/predicted G:F. Overall, the prediction equations suggest that increasing Leu:Lys negatively impacts ADG due to a reduction in G:F and ADFI caused by insufficient levels of other BCAA and LNAA relative to Leu. According to the model, the addition of Val, Ile, and Trp, alone or in combination, has the potential to counteract the negative effects of high dietary Leu concentrations on growth performance.

The response of weaned piglets to dietary valine and leucine

Valine (Val) is considered to be the fifth-limiting amino acid in a maize-soyabean meal diet for pigs. Excess leucine (Leu) levels often occur in commercial diets, which may attenuate the effect of Val deficiency because of an increased oxidation of Val. The objective of the present experiment was to determine the effect of increasing concentrations of Leu on the response of young piglets to dietary Val. In all, 75 Large White×Landrace entire male pigs, 44 days of age and with a mean starting weight of 13.5 kg, were used. Three of these were sacrificed at the start to determine their mean initial chemical composition. A summit feed first limiting in Val was serially diluted with a non-protein diluent to produce a series of five digestible Val concentrations of 11.9, 10.1, 8.3, 6.6 and 4.8 g/kg, with a sixth treatment being added to test that the feeds were limiting in Val. Three identical Val series, each with six levels of Val, were supplemented with increasing amounts of Leu (23, 45 and 67 g/kg), thus 18 treatments in total. All pigs were killed at the end of the trial after 18 days for analysis of water, protein, lipid and ash in the carcass. The levels of Val and Leu and their interaction significantly influenced all the measurements taken in the trial. Daily gain in liveweight, water and protein, and feed conversion efficiency all increased with dietary Val content, whereas feed intake decreased as both Val and Leu contents increased. The deleterious effect of increased Leu on feed intake and growth was more marked at lower levels of Val. Supplementing the feed with the lowest Val content with additional Val largely overcame the effect of excess Leu. The efficiency of utilisation of Val for protein growth was unaffected by the level of Leu in the feed, the primary response to excess Leu being a reduction in feed intake. An intake of around 9 g Val/day yielded maximal protein growth during the period from 44 to 62 days of age in pigs of the genotype used in this trial.

An estimate of the leucine requirement for young pigs

Three pig trials were done to estimate an objective requirement of young (10 to 20 kg) pigs for leucine (Leu). Within each trial, four or five replicates of five pigs were given ad libitum access to their experimental diet for a period of 21 (trial 1) or 19 days (trials 2 and 3). A Leu-deficient diet (177 g crude protein per kg) based on maize, peanut meal, lactose, sucrose, dried whey, maize starch, soya-bean meal (SBM), and gelatin was used in these trials. Trial 1 showed that the Leu-deficient diet supplemented with Leu produced responses in weight gain and gain/food ratio that were similar (P > 0·10) to that obtained from a maize-SBM-whey positive-control diet containing 213 g crude protein (CP) per kg. Trials 2 and 3 utilized graded levels of crystalline L-Leu to determine the minimal Leu requirement in young pigs. Both trials showed linear increases (P < 0·05) in weight gain and gain/food as a result of Leu supplementation. Closer examination of the data revealed no significant change in gain/food or PUN responses above 11·2 g/kg total Leu in trial 2, or in weight gain or PUN values above 11·5 g/kg total Leu in trial 3. These data indicate that the Leu requirement of young pigs is probably not greater than 11·5 g/kg (10·5 g/kg true digestible), which equates to approximately 0·72 g true digestible Leu per MJ metabolizable energy. The ideal ratio of Leu to Lys appears to be close to 1: 1 for pigs in the weight range of 10 to 20 kg.

Practical starter pig amino acid requirements in relation to immunity, gut health and growth performance

Immune system activation begins a host of physiological responses. Infectious agents are recognized by monocytes and macrophages which in turn stimulate cytokine production. It is the hormone-like factors called cytokines that orchestrate the immune response. The classic responses observed with immune system activation and cytokine production include: anorexia, fever, lethargy, recruitment of other immune cells, and phagocytosis. While production of immune system components is known to require some amino acids, increases in amino acid requirements are more than offset by the associated decrease in protein accretion and increased muscle protein degradation that also accompanies immune system activation. However, the biggest impact of cytokine production is a decrease in feed intake. Therefore, as feed intake decreases, the energy needed to drive protein synthesis is also decreased. This suggests that diets should still be formulated on a similar calorie:lysine ratio as those formulated for non-immune challenged pigs. The evidence is sparse or equivocal for increasing nutrient requirements during an immune challenge. Nutritionists and swine producers should resist the pressure to alter the diet, limit feed, or add expensive feed additives during an immune challenge. While immune stimulation does not necessitate changes in diet formulation, when pigs are challenged with non-pathogenic diarrhea there are potential advantages on gut health with the increased use of crystalline amino acids rather than intact protein sources (i.e., soybean meal). This is because reducing crude protein decreases the quantity of fermentable protein entering the large intestine, which lowers post weaning diarrhea. It also lowers the requirement for expensive specialty protein sources or other protein sources such as soybean meal that present immunological challenges to the gut. The objective of this review is two-fold. The first is to discuss immunity by nutrition interactions, or lack thereof, and secondly, to review amino acid requirement estimates for nursery pigs.

The Interaction Between Dietary Valine and Tryptophan Content and Their Effect on the Performance of Piglets

Four experimental diets for newly weaned pigs were formulated: (1) low valine and low tryptophan; (2) low valine and high tryptophan; (3) high valine and low tryptophan and (4) high valine and high tryptophan. Dietary standardized ileal digestible (SID) lysine content was 1.06 g/kg. The SID valine to SID lysine ratio was 0.58 and 0.67 for the low and high valine diets, respectively, and SID tryptophan to SID lysine ratios were 0.19 and 0.22 for the low and high tryptophan diets, respectively. In total, 64 pens of 6 pigs (3 barrows and 3 gilts) were divided over the four experimental treatments. No interaction between dietary supply of valine and tryptophan was observed (P > 0.1 for all parameters). Increasing the dietary valine content increased the daily feed intake, daily gain and gain:feed (P < 0.001 for all three parameters). Increasing the dietary tryptophan content improved gain:feed during the first 2 weeks (P < 0.05) and overall (P < 0.05). Valine supply had a greater effect on performance results than tryptophan supply. It may thus be beneficial to provide a diet with an optimal dietary concentration of valine even if other amino acids are at suboptimal dietary levels.

Estimation of the standardized ileal digestible valine-to-lysine ratio in 13- to 32-kilogram pigs

Three experiments were conducted to determine the optimum standardized ileal digestible Val-to-Lys (SID Val:Lys) ratio for 13- to 32-kg pigs. In Exp. 1, 162 pigs weaned at 17 d of age (8 pens/treatment) were used, and a Val-deficient basal diet containing 0.60% l-Lys·HCl, 1.21% SID Lys, and 0.68% SID Val was developed (0.56 SID Val:Lys). Performance of pigs fed the basal diet was inferior to a corn-soybean meal control containing only 0.06% l-Lys·HCl, but was fully restored with the addition of 0.146% l-Val to the basal diet (68% SID Val:Lys). In Exp. 2, 54 individually housed barrows (21.4 kg) were utilized in a 14-d growth assay. Pigs were offered a similar basal diet (1.10% SID Lys), ensuring Lys was marginally limiting with no supplemental l-Val (55% SID Val:Lys). The basal diet was fortified with 4 graded levels of l-Val (0.055% increments) up to a ratio of 75% SID Val:Lys. In Exp. 3, 147 barrows (13.5 kg) were fed identical diets, only with 1 additional level at a SID Val:Lys of 80% and fed for 21 d. In Exp. 2 and 3, a high protein, control diet was formulated to contain 1.10% SID Lys and 0.20% l-Lys·HCl. In Exp. 2, linear effects on ADG (713, 750, 800, 796, and 785 g/d; P = 0.05) and G:F (P = 0.07) were observed with increasing SID Val:Lys, characterized by improvements to a ratio of 65% and a plateau thereafter. In Exp. 3, quadratic improvements in ADG (600, 629, 652, 641, 630, and 642 g/d; P = 0.08) and G:F (P = 0.07) were observed with increasing SID Val:Lys, as performance increased to a ratio of 65% but no further improvement to a ratio of 80%. Pigs fed the control diet did not differ from those fed a ratio of 65% SID Val:Lys in Exp. 2, but did have improved G:F in Exp. 3 (P = 0.03). To provide a more accurate estimate of the optimum SID Val:Lys, data from Exp. 2 and 3 were combined. With single-slope broken-line methodology, the minimum ratio estimate was 64 and 65% SID Val:Lys for ADG and G:F, respectively. With combined requirement estimates, the data indicate that a SID Val:Lys of 65% seems adequate in maintaining performance for pigs from 13 to 32 kg.

The effect of cysteine analogues on the excretion of urinary sulphate in the rat following cysteine administration

A major pathway for the production of sulphate within the mammalian body is known to be via the oxidative degradation of the sulphur moiety within the amino acid, L-cysteine. The ability of two structurally similar sulphur-containing drugs, the anti-rheumatic agent, D-penicillamine, and the mucoactive compound, S-carboxymethyl-L-cysteine, to interfere with this sulphate production was investigated. Co-administration to the male rat of D-penicillamine (p.o.) and S-carboxymethyl-L-cysteine (p.o.) with [35S]-L-cysteine (i.p.) led to a significant decrease in the subsequent urinary elimination of inorganic sulphate whilst having no measurable effect on organic sulphate excretion. The co-administration of L-valine, an amino acid not containing sulphur, had no effect. It is not known where, within the complex sequence of events surrounding the degradation of cysteine to sulphate, that D-penicillamine or S-carboxymethyl-L-cysteine may interact.

Isoleucine requirement of growing (25 to 45 kg) pigs

Three pig bioassays and two digestibility trials were conducted to determine the true digestible Ile requirement for maximal weight gain and minimal plasma urea nitrogen (PUN) of growing (25 to 45 kg) pigs. In Exp. 1, an Ile-deficient basal diet was developed and confirmed to be markedly deficient in Ile, yet fully efficacious when fortified with surfeit Ile. This diet contained corn, red blood cells, and soybean meal as Ile sources, and was analyzed to contain 15.5% crude protein, 0.34% Ile, and 0.95% lysine; metabolizable energy was calculated to be 3,430 kcal/kg. True digestibility of Ile in the basal diet was 89% based on digestibility trials in ileal-cannulated pigs and cecectomized roosters. The first growth trial (Exp. 2) involved six dose levels of true digestible Ile (0.38 to 0.58%), which resulted in a quadratic (P < 0.02) response in weight gain by growing pigs over a 21-d period. The weight-gain data were fitted to both a single-slope broken line and a quadratic fit, and when the quadratic response curve was superimposed on the broken line, the point at which the quadratic curve first intersected the plateau of the broken line occurred at 0.50% true digestible Ile. This (objective) requirement estimate was similar to that determined by taking 90% of the upper asymptote of the quadratic fitted line. In Exp. 3, a replicated 5 x 5 Latin square, five barrows (square 1) and five gilts (square 2) together with five 4-d feeding periods and five levels of true digestible Ile were utilized. A linear (P < 0.01) decrease in PUN occurred as Ile was incremented, with an apparent plateau occurring at 0.50% true digestible Ile. The results of these experiments suggest that the true digestible Ile requirement of grower (25 to 45 kg) pigs is 0.50% of the diet, or 1.46 g/Mcal of metabolizable energy, somewhat higher than the 1.38 g/Mcal metabolizable energy estimated by the 1998 National Research Council Subcommittee on Swine Nutrition.