The relevance of functional amino acids to support the health of growing pigs

Plasma proteomic analysis reveals key pathways associated with divergent residual body weight gain phenotype in beef steers

We utilized plasma proteomics profiling to explore metabolic pathways and key proteins associated with divergent residual body weight gain (RADG) phenotype in crossbred (Angus × Hereford) beef steers. A group of 108 crossbred growing beef steers (average BW = 282.87 ± 30 kg; age = 253 ± 28 days) were fed a high-forage total mixed ration for 49 days in five dry lot pens (20-22 beef steers per pen), each equipped with two GrowSafe8000 intake nodes to determine their RADG phenotype. After RADG identification, blood samples were collected from the beef steers with the highest RADG (most efficient; n = 15; 0.76 kg/d) and lowest RADG (least efficient; n = 15; -0.65 kg/d). Plasma proteomics analysis was conducted on all plasma samples using a nano LC-MS/MS platform. Proteins with FC ≥ 1.2 and false-discovery rate-adjusted p-values (FDR) ≤ 0.05 were considered significantly differentially abundant. The analysis identified 435 proteins, with 59 differentially abundant proteins (DAPs) between positive and negative-RADG beef steers. Plasma abundance of 38 proteins, such as macrophage stimulating 1 and peptidase D was upregulated (FC ≥ 1.2, FDR ≤ 0.05) in positive-RADG beef steers, while 21 proteins, including fibronectin and ALB protein were greater (FC < 1.2, FDR ≤ 0.05) in negative-RADG beef steers. The results of the Gene Ontology (GO) analysis of all the DAPs showed enrichment of pathways such as metabolic processes, biological regulation, and catalytic activity in positive-RADG beef steers. Results of the EuKaryotic Orthologous Groups (KOG) analysis revealed increased abundance of DAPs involved in energy production and conversion, amino acid transport and metabolism, and lipid transport and metabolism in positive-RADG beef steers. The results of this study revealed key metabolic pathways and proteins associated with divergent RADG phenotype in beef cattle which give more insight into the biological basis of feed efficiency in crossbred beef cattle.

Increased Dietary Trp, Thr, and Met Supplementation Improves Performance, Health, and Protein Metabolism of Weaned Piglets under Mixed Management and Poor Housing Conditions

A sanitary challenge was carried out to induce suboptimal herd health while investigating the effect of amino acids supplementation on piglet responses. Weaned piglets of high sanitary status (6.33 ± 0.91 kg of BW) were distributed in a 2 × 2 factorial arrangement into two similar facilities with contrasting sanitary conditions and two different diets. Our results suggest that increased Trp, Thr, and Met dietary supplementation could support the immune systems of piglets under a sanitary challenge. In this manner, AA+ supplementation improved the performance and metabolism of piglets under mixed management and poor sanitary conditions. No major temporal microbiome changes were associated with differences in performance regardless of sanitary conditions or diets. Since piglets often become mixed in multiple-site production systems and facility hygiene is also often neglected, this study suggests that increased Trp, Thr, and Met (AA+) dietary supplementation could contribute to mitigating the side effects of these harmful risk factors in modern pig farms.

Effects of increasing dietary arginine supply during the three first weeks after weaning on pig growth performance, plasma amino acid concentrations, and health status

A total of 425 weaned pigs (Exp. 1: 225 pigs [5.8 ± 0.9 kg]; Exp. 2: 200 pigs [6.1 ± 1.2 kg]) were used to determine the optimal dietary standardized ileal digestible (SID) arginine (Arg) level in early nursery diets based on growth and health responses. The basal diet in Exp.1 was formulated to meet SID Arg recommendation (0.66%; NRC, 2012) and in Exp. 2, SID Arg was set to simulate current industry practices for feeding nursery pigs (1.15 %). Basal diets were supplemented with 0.3%, 0.6%, 0.9%, and 1.2% of l-arginine to provide five levels of dietary SID Arg. Experimental diets were fed during phases I (days 0 to 7) and II (days 8 to 21) with common diets until market. Feed disappearance and body weight (BW) were measured on days 7, 14, 21, and 43. Final BW was recorded at first removal of pigs for market. Pen fecal score was assigned daily from days 0 to 21. Plasma immunoglobulin A (IgA) was determined on days 0, 7, and 14 and amino acids (AAs) concentration and plasma urea nitrogen (PUN) on days 0 and 14. Orthogonal polynomial contrasts were used to determine the linear and quadratic effects of dietary Arg. Optimal SID Arg was determined by fitting the data with piecewise regression, using growth performance as the primary response variable. In Exp. 1, dietary Arg linearly increased (P < 0.1) BW, average daily gain (ADG), and gain to feed ratio (G:F) ratio on day 21, as well as reduced (χ2 = 0.004) the percentage of pigs that lost weight (PLW) in week 1 by 29%. Dietary Arg resulted in linear improvement (P = 0.082) of ADG for the overall nursery period and quadratic improvement (P < 0.1) of final BW at marketing. In Exp. 2, dietary Arg linearly increased (P < 0.05) ADG and average daily feed intake (ADFI) in week 1, BW and ADFI (P < 0.1) on day 14, as well as reduced (χ2 ≤ 0.001) PLW in week 1. From days 0 to 21, G:F was improved quadratically (P < 0.1). Dietary Arg linearly increased (P < 0.1) ADG and BW on day 43. Dietary Arg supplementation decreased the incidence (χ2 < 0.05) of soft and watery feces during the first weeks after weaning and lower concentration of plasma IgA on days 7 and 14. Dietary Arg linearly and/or quadratically influenced plasma AA concentrations (P < 0.05), including an increase in Arg, Leu, Phe, Val, citrulline, ornithine, and PUN concentrations. Overall, weaned pigs exhibit optimal nursery growth performance and health when provided with dietary SID Arg ranging from 1.5% to 1.9%. This dietary range contributes to a reduction in the occurrence of fall-back pigs and improvements in final BW at marketing.

Size matters: lower body weight pigs have a different response to immune challenge and amino acids supplementation above the estimated requirement compared to heavy pigs

The immune response varies between pigs, as not all pigs have the same response to a stressor. This variation may exist between individuals due to body weight (BW) or body composition, which may impact the capacity for coping with an immune challenge (IC). Tryptophan (Trp), threonine (Thr), and methionine (Met) requirements might also play a considerable part in supporting immune system activation while reducing variation between pigs; however, the latter has yet to be reported. This exploratory study investigated the effect of initial BW (light vs. heavy-weight) and supplementation of Trp, Thr, and Met above National Research Council (NRC) requirements on feeding behavior and the coping capacity of growing pigs under an IC. Eighty gilts were categorized into 2 groups according to BW: light-weight (LW, 22.5 kg) and heavy-weight pigs (HW, 28.5 kg). Both BW groups were group-housed for a 28-d trial in a good or poor sanitary condition (SC). Pigs within a poor SC were orally inoculated with 2 × 109 colony units of Salmonella Typhimurium, and fresh manure from a pig farm was spread on the floor. Pigs within good SC were not inoculated, nor was manure spread. Two diets were provided within each SC: control (CN) or supplemented (AA+) with Trp, Thr, and Met at 120% of NRC recommended levels. A principal component analysis was performed in R, and a feeding behavior index was calculated in SAS. Results showed that LW and HW pigs were clustered separately on day 0, where LW pigs had a positive correlation with body lipid percentage (r = 0.83), and HW pigs had a positive correlation with body protein percentage (r = 0.75). After the IC, the cluster configuration changed, with diets influencing LW more than HW pigs within poor SC. On day 14, LW fed AA + diet in poor SC was clustered separately from LW pigs fed CN diet, whereas LW fed AA + and CN diets in good SC were clustered together. For feeding behavior, in both analyzed periods (period 1: days 7 to 14; period 2: days 21 to 28), LW had lower total feed intake and shorter meals than HW pigs (P < 0.10), independent of the SC. Furthermore, LW pigs fed AA + diet had a more regular feed intake pattern than those fed CN diet, while a more irregular pattern was observed for HW pigs fed AA + diet than CN diet at period 2. These findings suggest that supplementing Trp, Thr, and Met above requirements may be a nutritional strategy for LW pigs under IC by improving feed intake regularity and reducing the probability of being susceptible to IC.

A blend of bacillus-fermented soybean meal, functional amino acids, and nucleotides improves nutrient digestibility, bolsters immune response, reduces diarrhea, and enhances growth performance in weaned piglets

This study investigated the effects of a blend of bacillus-fermented soybean meal, functional amino acids, and nucleotides (Functional protein blend-FP Blend) as a replacement for animal protein sources in a weaner pig diet without antibiotic growth promoters on nutrient digestibility, blood profiles, intestinal morphology, diarrhea incidence, and growth performance. A total of 288 crossbred weaned piglets [♂ Duroc x ♀ (Yorkshire × Landrace)] with an average body weight (BW) of 6.89 ± 0.71 kg were randomly allocated to 6 groups based on initial BW and sex (8 replicate pens per treatment; 3 gilts and 3 barrows/pen). The experiment lasted for 5 wk. Dietary treatments included PC [standard diet with 3% fish meal (FM) and 2% plasma protein (PP)], NC (nonanimal protein, AP), T1 (3% FM replaced with 5% FP Blend), T2 (3% FM and 1% PP replaced with 5% FP Blend), T3 (2% PP replaced with 5% FP Blend), and T4 (3% FM and 2% PP replaced with 5% FP Blend). Data were analyzed using Minitab version 17 software. Key results indicated that FP Blend improved the apparent ileal digestibility (AID) coefficient of dry matter, gross energy, lysine, and valine in T4 compared with NC treatment (P < 0.05), whereas AID coefficient of crude protein and other amino acids remained constant (P > 0.05). Compared with NC diet, the weaned pigs fed T4 diet reduced malondialdehyde, serum IL8, TNF-α, and increased IgG (P < 0.05), while showing no effect on serum IL6, IL10, white blood cells, IgA, and endotoxin (P > 0.05). Furthermore, FP blend significantly increased villus height in the duodenum and ileum in T4 compared with NC (P < 0.05). The average daily gain (ADG) was highest in T4 (502.73 g/d), followed by T1 (477.96 g/d) and T2 (475.85 g/d), compared with PC (450.86 g/d) and NC (439.79 g/d). T4's ADG significantly differed from PC and NC (P < 0.001), whereas no significant differences were observed in T1, T2, and T3 (P > 0.05). The feed conversion ratio (FCR) was significantly lower in T4 (1.45) compared with PC (1.57) and NC (1.59) (P < 0.001), with no significant differences among other groups. In conclusion, FP Blend demonstrated efficacy in improving nutrient digestibility, optimizing intestinal morphology, bolstering immune responses, reducing diarrhea incidence, alleviating the adverse effects of weaning stress, and enhancing growth performance of weaned piglets.

Effects of Protease in Soybean Meal-Reduced Diets on Growth Performance, Nutrient Digestibility, and Intestinal Health of Weaned Piglets

This experiment was conducted in weaned piglets to determine the effects of exogenous protease to low soybean meal (SBM) diets on growth performance, diarrhea rate, nutrient digestibility, and intestinal morphology. Seventy-two Duroc × Landrace × Yorkshire weaned barrows (21-day-old, 5.88 ± 0.95 kg) were randomly divided into four treatments with six replicates in each following a 2 × 2 factorial arrangement of SBM levels (0 to 14 d, 9%, 7.5%; 15 to 42 d, 20%, 18.5%) and protease (0 or 150 mg/kg) for a 42-day trial. Fecal samples were collected on days 11 to 14 and 38 to 42 of the experiment, and serum, intestinal tissue, and chyme samples were taken at the end of the experiments. Adding protease in low SBM diets had a significant increase in ADG (p < 0.05) and a decrease in F/G (p < 0.05). Protease significantly reduced the diarrhea rate (p < 0.05). Low SBM level decreased the apparent total tract digestibility (ATTD) of crude protein (CP) and ash (p < 0.05) but increased the ATTD of dry matter (DM), ash, organic matter (OM), and CP after the addition of protease (p < 0.05). The apparent ileal digestibility (AID) of aspartic acid (Asp), threonine (Thr), serine (Ser), alanine (Ala), lysine (Lys), and total amino acids (AAs) were significantly increased by protease supplementation (p < 0.05). Both the SBM-reduced and protease-added diets lead to lower albumin (ALB), albumin/globulin (A/G), and urea nitrogen (UREA) (p < 0.05), but greater globulin (GLOB) with low SBM diets (p < 0.05). The SBM-reduced and protease-added diets decreased the duodenum pH, respectively (p < 0.05). The protease increased the villus:crypt (V:C) in the duodenum and ileum, and ileal villus length (p < 0.05). In conclusion, the dietary supplementation of 150 mg/kg protease improved the intestinal health and performance of the weaned piglets and reversed the negative effect of a 1.5% SBM reduction in nutrient utilization, intestinal pH, and intestinal morphological parameters of weaned piglets.

The use of functional amino acids in different categories of pigs - A review

The present review deals with a particularly important topic: the use of functional amino acids in different categories of pigs. It is especially relevant in the context of the current efforts to reduce the use of antibiotics in pig farming and the search for possible alternatives to replace them. The review is based on the definition that functional amino acids (FAAs) are classified as dispensable amino acids, but with additional biological functions, i.e., not only are they used for protein formation, but they are also involved in regulating essential metabolic pathways to improve health, survival, growth, and development. We describe the mechanism of action of individual FAAs and their potential use in pigs, including glutamate, glutamine, arginine, branched-chain amino acids (i.e., leucine, isoleucine, and valine), tryptophan and glycine. The work is divided into three parts. The first part deals with the FAAs and their role in the overall health of sows and their offspring. The second part describes the use of functional amino acids in piglets after weaning. Part three examines the use of functional amino acids in growing and fattening pigs and their impact on meat quality.

Review: A systematic review of the effects of functional amino acids on small intestine barrier function and immunity in piglets

The need to reduce the use of antibiotics and zinc oxide at the pharmacological level, while preserving the performance of postweaning piglets, involves finding adequate nutritional strategies which, coupled with other preventive strategies, act to improve the sustainability of the piglet-rearing system. Amino acids (AAs) are the building blocks of proteins; however, they also have many other functions within the body. AA supplementation, above the suggested nutritional requirement for piglets, has been investigated in the diets of postweaning piglets to limit the detrimental consequences occurring during this stressful period. A systematic review was carried out to summarise the effects of AAs on gut barrier function and immunity, two of the parameters contributing to gut health. An initial manual literature search was completed using an organised search strategy on PubMed, utilising the search term " AND ". These searches yielded 302 articles (published before October 2021); 59 were selected. Based on the method for extracting data (synthesis of evidence), this review showed that L-Arginine, L-Glutamine and L-Glutamate are important functional AAs playing major roles in gut morphology and immune functions. Additional benefits of AA supplementation, refereed to a supplementation above the suggested nutritional requirement for piglets, could also be observed; however, data are needed to provide consistent evidence. Taken together, this review showed that supplementation with AAs during the weaning phase supported a plethora of the physiological functions of piglets. In addition, the data reported confirmed that each amino acid targets different parameters related to gut health, suggesting the existence of potential synergies among them.

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.

Impact of L-Arginine and L-Glutamine supplementation on growth performance and immune status in weanling pigs challenged with Escherichia coli F4

Arginine (ARG) and Glutamine (GLN) have been reported to play significant roles in protein metabolism, immunity, and intestinal health in weanling pigs. The present study investigated the independent and interactive effect of supplementing ARG and GLN on pigs immune status and growth performance following an Escherichia coli F4 challenge. A total of 240 mixed-sex pigs (24 ± 2 d old; 7.3 ± 0.1 kg BW) were used in a 42-d experiment after selection for E. coli F4 susceptibility. The pigs were group-housed (3 pigs per pen), and pens were randomly assigned to five experimental treatments (N = 16 pens per treatment). Experimental treatments were: 1) a wheat-barley-soybean meal-based basal diet (CTRL), 2) a basal diet with 2500 mg/kg zinc oxide (ZnO), 3) a basal diet + 0.5% Glutamine (0.5% GLN), 4) basal diet + 0.5% Arginine (0.5% ARG), and 5) basal diet with 0.5% Glutamine + 0.5% Arginine (0.5% GLN + ARG). All Pigs were inoculated with E. coli F4 on days 7, 8, and 9 post-weaning. Rectal swabs were taken from each pig and plated on blood agar plates for E. coli F4 presence. Blood and fecal samples were taken to determine the acute phase response and selected fecal biomarkers for the immune response. Growth performance and fecal scores were recorded. Fecal swabs resulted in no positive pig for E. coli F4 before inoculation and 73.3% positive postinoculation. Diarrhea incidence during days 7 to 14 was significantly lower for the ZnO treatment (P < 0.05). The haptoglobin level on day 3 was lower than days 10 and 20, irrespective of treatment (P < 0.05). The albumin level was lower on day 20 compared to days 3 and 10 (P < 0.05). There was no treatment effect on albumin levels regardless of sampling day (P > 0.05). The PigMAP was lowest on day 3 and highest on day 10 (P < 0.05). We did not observe significant treatment differences (P > 0.05) in myeloperoxidase and calprotectin. Pancreatitis-associated protein was higher in the ZnO (P = 0.001) treatment than in the other treatments. Fecal IgA tended (P = 0.10) to be higher in the ZnO and 0.5% ARG treatments. There were no performance differences, except during days 0 to 7, where the ZnO treatment was lower in average daily gain and average daily feed intake (P < 0.001), while feed efficiency (G:F) FE was similar across treatments. In summary, no improved performance was observed with either ARG, glutamate, or both. The immune response results showed that the E. coli F4 challenge may have exacerbated the acute phase response; hence, the benefits of dietary treatments did not go beyond immune repair and reduction in inflammation.

Impact of dietary supplementation of l-Arginine, l-Glutamine, and the combination of both on nursing performance of multiparous sows

Dietary supplementation with arginine (Arg) or glutamine (Gln) has been considered as an option to improve nursing performance in reproductive sows. This study investigated whether a low-level supplementation of Arg or Gln or a blend of both could modify milk nutrients and improve piglets' growth beyond weaning. Seventy-two multiparous sows were assigned to four groups: one group fed a control diet, three treatment groups fed the control diet supplemented with either 0.35% Arg, 0.35% Gln, or both, from day 108 of gestation until weaning at day 26 of lactation. Immediately after birth, the litters were cross fostered to 13 piglets and monitored until 2 wk after weaning. Sows body condition and litter growth were assessed. Colostrum and milk samples were collected for nutrient analyses. Plasma concentrations of insulin-like growth factor 1 (IGF-1) around weaning were determined in sows and two representative piglets per litter. Supplementing Gln or the combination of Arg and Gln had no effect on the parameters studied. Arg supplementation increased weaning weight, while decreasing the variation of piglet weights 2 wk after weaning. There was no correlation with plasma IGF-1 since the hormone was not altered in sows or piglets. The colostral concentration of fat tended to increase in the Arg-group, whereas protein, lactose, energy, and polyamine concentrations remained unaffected. Milk samples obtained on day 12 and 25 of lactation were not influenced by dietary treatment. The data indicate that there might be a window of opportunity, explicitly at the onset of lactation, for dietary intervention by maternal dietary Arg supplementation.

Physiological and Metabolic Adaptation to Heat Stress at Different Altitudes in Yaks

Yaks have strong adaptability to extremely cold and hypoxic conditions but are susceptible to high ambient temperature when yaks are raised in low-altitude areas during the high-temperature season. Twenty-four adult male yaks with similar weights and ages were randomly divided into TN (Thermoneutral, altitude = 3464 m), LHS (Light heat stress, altitude = 1960 m), and MHS (Medium heat stress, altitude = 906 m) groups to evaluate adaptation strategies to HS. Non-targeted and targeted metabolomics were applied to investigate the effects of different extents of HS on yaks. LHS- and MHS-yaks showed higher rectal temperatures and respiratory rates than TN-yaks. MHS-yaks had higher levels of red blood cells (RBCs), hemoglobin (Hb), whole blood relative index of middle shear at a shear rate of 5 S-1 (WMS), whole blood relative index of high shear at a shear rate of 200 S-1 (WHS), Casson viscosity (CV), middle shear flow resistance at a shear rate of 5 S-1 (MSFR), and high shear flow resistance at a shear rate of 200 S-1 (HSFR) as compared to TN- and LHS-yaks. Differential metabolites and metabolic pathways, including fatty acid metabolism, lipid metabolism, glucose metabolism, and amino acid metabolism, were altered by HS. Metabolites in the glucose metabolism pathway in LHS- and MHS-yaks were lower than those in TN-yaks. However, LHS-yaks showed higher levels of metabolites in the HIF-1 signaling pathway compared to TN- and MHS-yaks. Most of the tricarboxylic acid cycle (TCA) intermediates and fatty acids were significantly decreased in MHS-yaks compared to the other two groups. As a whole, yaks raised at a low altitude (25.6 °C) suffered from severe HS, but they adapted to HS with vasodilatation for dissipating heat and the increased antioxidants and metabolite levels of energy substrates.

Formulating Diets for Improved Health Status of Pigs: Current Knowledge and Perspectives

Our understanding of nutrition has been evolving to support both performance and immune status of pigs, particularly in disease-challenged animals which experience repartitioning of nutrients from growth towards the immune response. In this sense, it is critical to understand how stress may impact nutrient metabolism and the effects of nutritional interventions able to modulate organ (e.g., gastrointestinal tract) functionality and health. This will be pivotal in the development of effective diet formulation strategies in the context of improved animal performance and health. Therefore, this review will address qualitative and quantitative effects of immune system stimulation on voluntary feed intake and growth performance measurements in pigs. Due to the known repartitioning of nutrients, the effects of stimulating the immune system on nutrient requirements, stratified according to different challenge models, will be explored. Finally, different nutritional strategies (i.e., low protein, amino acid-supplemented diets; functional amino acid supplementation; dietary fiber level and source; diet complexity; organic acids; plant secondary metabolites) will be presented and discussed in the context of their possible role in enhancing the immune response and animal performance.

Functional amino acid supplementation attenuates the negative effects of plant-based nursery diets on the response of pigs to a subsequent Salmonella Typhimurium challenge

Functional amino acids (FAA) attenuate the effects of Salmonella challenge in pigs. However, this may be affected by protein source (PS). The objective of the present study was to determine the effects of nursery dietary PS and FAA supplementation on growth performance and immune status of pigs subsequently challenged with Salmonella Typhimurium (ST). Thirty-two weanling pigs (8.7 ± 0.23 kg) were assigned to a feeding program for 31 d in a 2 × 2 factorial arrangement. Factors were dietary PS (plant-based [PB] vs. animal-based [AB]) and FAA profile (basal [FAA-] or supplemented [FAA+; Thr, Met, and Trp at 120% of requirements]). Pigs were subsequently placed on a common grower diet and, after a 7-d adaptation, were inoculated with ST and monitored for 7 d postinoculation. Growth performance, rectal temperature, fecal score, gut health, ST shedding score, intestinal colonization and translocation, and blood parameters of acute-phase response and antioxidant balance were measured pre- and postinoculation. Data were analyzed with a 2 (AB vs. PB) × 2 (FAA- vs. FAA+) factorial arrangement of treatments and differences between means were considered significant at P ≤ 0.05. Postinoculation fecal score was worse, ST shedding, cecal myeloperoxidase, and cecal and colonic ST colonization were greater in PB compared to AB pigs (P < 0.05). Translocation of ST to spleen was decreased by FAA+ (P < 0.05), regardless of dietary PS. Postinoculation, AB pigs had greater average daily gain compared to PB-FAA- (P < 0.05). Pigs fed AB-FAA- showed increased average daily feed intake compared to PB-FAA- pigs (P < 0.05) and feed efficiency was increased in AB-FAA+ compared to PB-FAA- pigs (P < 0.05). Feeding PB ingredients in nursery diets seems to increase susceptibility of pigs to Salmonella. Moreover, FAA supplementation partially attenuated the negative effects of PB diets on the response of pigs to ST challenge.

Urea Nitrogen Metabolite Can Contribute to Implementing the Ideal Protein Concept in Monogastric Animals

Simple Summary

Can urea nitrogen metabolite contribute to implementing the ideal protein concept in monogastric animals? This work aims to critically analyse how this metabolite can contribute to accurately implementing the ideal protein concept in monogastric animals, particularly in pig, poultry, and rabbit nutrition. This information will contribute to evaluating its potential and limitations as biomarker, as well as to standardizing the use of this metabolite in precise amino acidic monogastric nutrition.

Abstract

The ideal protein concept refers to dietary protein with an amino acid profile that exactly meets an animal’s requirement. Low-quality protein levels in the diet have negative implications for productive and reproductive traits, and a protein oversupply is energetically costly and leads to an excessive N excretion, with potentially negative environmental impact. Urea Nitrogen (UN), which corresponds to the amount of nitrogen in the form of urea circulating in the bloodstream, is a metabolite that has been widely used to detect amino acid imbalances and deficiencies and protein requirements. This review aims to critically analyse how UN can contribute to accurately implementing the ideal protein concept in monogastric animals, particularly in pig, poultry, and rabbit nutrition (14,000 animals from 76 published trials). About 59, 37, and 4% of trials have been conducted in pigs, poultry, and rabbits, respectively. UN level was negatively correlated to main performance traits (Pearson Correlation Coefficient [PCC] of −0.98 and −0.76, for average daily gain and feed conversion ratio, respectively), and lower UN level was related to higher milk yield and concentration. High level of UN was positively correlated to N excretion (PCC = 0.99) and negatively correlated to protein retention (PCC = −0.99). Therefore, UN in blood seems to be a proper indicator of amino acid imbalance in monogastric animals. Great variability in the use of UN was observed in the literature, including uses as determination medium (blood, plasma, or serum), units, and feeding system used (ad libitum or restricted), among others. A standardization of the methods in each of the species, with the aim to harmonize comparison among works, is suggested. After review, UN measurement in plasma and, whenever possible, the utilization of the same nutritional methodology (ad libitum conditions or restriction with blood sampling after refeeding at standardised time) are recommended. More studies are necessary to know the potential of UN and other bioindicators for amino acid deficiencies evaluation to get closer to the ideal protein concept.

Invited review: strategic adoption of antibiotic-free pork production: the importance of a holistic approach

The discovery of the use of antibiotics to enhance growth in the 1950s proved to be one of the most dramatic and influential in the history of animal agriculture. Antibiotics have served animal agriculture, as well as human and animal medicine, well for more than seven decades, but emerging from this tremendous success has been the phenomenon of antimicrobial resistance. Consequently, human medicine and animal agriculture are being called upon, through legislation and/or marketplace demands, to reduce or eliminate antibiotics as growth promotants and even as therapeutics. As explained in this review, adoption of antibiotic-free (ABF) pork production would represent a sea change. By identifying key areas requiring attention, the clear message of this review is that success with ABF production, also referred to as "no antibiotics ever," demands a multifaceted and multidisciplinary approach. Too frequently, the topic has been approached in a piecemeal fashion by considering only one aspect of production, such as the use of certain feed additives or the adjustment in health management. Based on the literature and on practical experience, a more holistic approach is essential. It will require the modification of diet formulations to not only provide essential nutrients and energy, but to also maximize the effectiveness of normal immunological and physiological capabilities that support good health. It must also include the selection of effective non-antibiotic feed additives along with functional ingredients that have been shown to improve the utility and architecture of the gastrointestinal tract, to improve the microbiome, and to support the immune system. This holistic approach will require refining animal management strategies, including selection for more robust genetics, greater focus on care during the particularly sensitive perinatal and post-weaning periods, and practices that minimize social and environmental stressors. A clear strategy is needed to reduce pathogen load in the barn, such as greater emphasis on hygiene and biosecurity, adoption of a strategic vaccine program and the universal adoption of all-in-all-out housing. Of course, overall health management of the herd, as well as the details of animal flows, cannot be ignored. These management areas will support the basic biology of the pig in avoiding or, where necessary, overcoming pathogen challenges without the need for antibiotics, or at least with reduced usage.

Influence of the Gut Microbiome on Feed Intake of Farm Animals

With the advancement of microbiome research, the requirement to consider the intestinal microbiome as the “last organ” of an animal emerged. Through the production of metabolites and/or the stimulation of the host’s hormone and neurotransmitter synthesis, the gut microbiota can potentially affect the host’s eating behavior both long and short-term. Based on current evidence, the major mediators appear to be short-chain fatty acids (SCFA), peptide hormones such as peptide YY (PYY) and glucagon-like peptide-1 (GLP-1), as well as the amino acid tryptophan with the associated neurotransmitter serotonin, dopamine and γ-Aminobutyrate (GABA). The influence appears to extend into central neuronal networks and the expression of taste receptors. An interconnection of metabolic processes with mechanisms of taste sensation suggests that the gut microbiota may even influence the sensations of their host. This review provides a summary of the current status of microbiome research in farm animals with respect to general appetite regulation and microbiota-related observations made on the influence on feed intake. This is briefly contrasted with the existing findings from research with rodent models in order to identify future research needs. Increasing our understanding of appetite regulation could improve the management of feed intake, feed frustration and anorexia related to unhealthy conditions in farm animals.

Functional amino acid supplementation postweaning mitigates the response of normal birth weight more than for low birth weight pigs to a subsequent Salmonella challenge

Previous work has shown that dietary supplementation with key functional amino acids (FAA) improves growth performance and immune status of disease-challenged normal birth weight (NBW) pigs. It is not known whether FAA supplementation attenuates the effects of a subsequent disease challenge or whether this response is similar in low birth weight (LBW) pigs. The objective was to determine the effects of birth weight and FAA supplementation during the postweaning period in Salmonella-challenged pigs. Thirty-two LBW (1.08 ± 0.11 kg) and NBW (1.58 ± 0.11 kg) pigs were assigned to a nursery feeding program at weaning (25 d) for 31 days in a 2 × 2 factorial arrangement. Factors were birth weight category (LBW vs. NBW) and basal (FAA-) or supplemented FAA profile (FAA+; Thr, Met, and Trp at 120% of requirements). At d 31, pigs were placed onto a common grower diet and, after a 7-d adaptation period, were inoculated with Salmonella Typhimurium (ST; 2.2 × 10⁹ colony-forming units/mL) and monitored for 7-d postinoculation. Growth performance, rectal temperature, fecal score, indicators of gut health, ST shedding score in feces, intestinal ST colonization and translocation, and blood parameters of acute-phase response and antioxidant balance were measured pre- and postinoculation. Inoculation with ST increased temperature and fecal score, and the overall rectal temperature was higher in LBW compared to NBW pigs (P < 0.05). Postinoculation (d 7), reduced:oxidized glutathione was increased in NBW compared to LBW pigs (P < 0.05). Salmonella shedding and translocation to spleen were lower in NBW-FAA+ compared to NBW-FAA- pigs (P < 0.05). Postinoculation average daily gain was higher in NBW-FAA+ (P < 0.05) compared to the other groups. Postinoculation haptoglobin, superoxide dismutase, and colonic myeloperoxidase were increased in LBW-FAA- pigs (P < 0.05). Ileal alkaline phosphatase was decreased in LBW compared to NBW (P < 0.05). Overall, FAA supplementation represents a potential strategy to mitigate the effect of enteric disease challenge in NBW, but not LBW pigs.

The "ideal protein" concept is not ideal in animal nutrition

Amino acids (AAs) are required for syntheses of proteins and low-molecular-weight substances with enormous physiological importance. Since 1912, AAs have been classified as nutritionally essential amino acids (EAAs) or nonessential amino acids (NEAAs) for animals. EAAs are those AAs that are either not synthesized or insufficiently synthesized de novo in the organisms. It was assumed that all NEAAs (now known as AAs that are synthesizable in animal cells de novo [AASAs]) were formed sufficiently in animals and were not needed in diets. However, studies over the past three decades have shown that sufficient dietary AASAs (e.g. glutamine, glutamate, glycine, and proline) are necessary for the maximum growth and optimum health of pigs, chickens, and fish. Thus, the concept of "ideal protein" (protein with an optimal EAA pattern that precisely meets the physiological needs of animals), which was originally proposed in the 1950s but ignored AASAs, is not ideal in animal nutrition. Ideal diets must provide all physiologically and nutritionally essential AAs. Improved patterns of AAs in diets for swine and chickens as well as zoo and companion animals have been proposed in recent years. Animal-sourced feedstuffs supply abundant EAAs and AASAs (including glutamate, glutamine, glycine, proline, 4-hydroxyproline, and taurine) for diets of swine, poultry, fish, and crustaceans to improve their growth, development, reproduction, and health, while sustaining global animal production. Nutritionists should move beyond the "ideal protein" concept to consider optimum ratios and amounts of all proteinogenic AAs in diets for mammals, birds, and aquatic animals, and, in the case of carnivores, also taurine.

Functional roles of taurine, L-theanine, L-citrulline, and betaine during heat stress in poultry

Heat stress (HS) is an important environmental stress factor affecting poultry production on a global scale. With the rise in ambient temperature and increasing effects of global warming, it becomes pertinent to understand the effects of HS on poultry production and the strategies that can be adopted to mitigate its detrimental impacts on the performance, health, welfare, immunity, and survival of birds. Amino acids (AAs) have been increasingly adopted as nutritional modifiers in animals to ameliorate the adverse effects of HS. They are essential for protein synthesis, growth, maintenance, reproduction, immunity, stress response, and whole-body homeostasis. However, HS tends to adversely affect the availability, transport, absorption, and utilization of these AAs. Studies have investigated the provision of these AAs to poultry during HS conditions, and variable findings have been reported. Taurine, L-theanine, and L-citrulline are non-essential amino acids that are increasingly gaining attention as nutritional supplements in HS animals. Similarly, betaine is an amino acid derivative that possesses favorable biological properties which contributes to its role as a functional additive during HS. Of particular note, taurine is negligible in plants, while betaine, L-theanine, and L-citrulline can be found in selected plants. These nutrients are barely found in feed ingredients, but their supply has been shown to elicit important physiological roles including anti-stress effects, anti-oxidative, anti-inflammatory, gut promoting, and immunomodulatory functions. The present review provides information on the use of these nutritionally and physiologically beneficial nutrients as functional additives to poultry diets during HS conditions. Presently, although several studies have reported on the positive effects of these additives in human and murine studies, however, there is limited information regarding their utilization during heat stress in poultry nutrition. Therefore, this review aims to expound on the functional properties of these nutrients, their potentials for HS alleviation, and to stimulate further researches on their biological roles in poultry nutrition.

Feeding intact proteins, peptides, or free amino acids to monogastric farm animals

For terrestrial farm animals, intact protein sources like soybean meal have been the main ingredients providing the required amino acids (AA) to sustain life. However, in recent years, the availability of hydrolysed protein sources and free AA has led to the use of other forms of AA to feed farm animals. The advent of using these new forms is especially important to reduce the negative environmental impacts of animal production because these new forms allow reducing the dietary crude protein content and provide more digestible materials. However, the form in which dietary AA are provided can have an effect on the dynamics of nutrient availability for protein deposition and tissue growth including the efficiency of nutrient utilization. In this literature review, the use of different forms of AA in animal diets is explored, and their differences in digestion and absorption rates are focused on. These differences affect the postprandial plasma appearance of AA, which can have metabolic consequences, like greater insulin response when free AA or hydrolysates instead of intact proteins are fed, which can have a profound effect on metabolism and growth performance. Nevertheless, the use and application of the different AA forms in animal diets are important to achieve a more sustainable and efficient animal production system in the future, as they allow for a more precise diet formulation and reduced negative environmental impact. It is, therefore, important to differentiate the physiological and metabolic effects of different forms of AA to maximize their nutritional value in animal diets.

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.

A mix of functional amino acids and grape polyphenols promotes the growth of piglets, modulates the gut microbiota in vivo and regulates epithelial homeostasis in intestinal organoids

Weaning is a challenging period for gut health in piglets. Previous studies showed that dietary supplementations with either amino acids or polyphenols promote piglet growth and intestinal functions, when administered separately. Thus, we hypothesized that a combination of amino acids and polyphenols could facilitate the weaning transition. Piglets received during the first two weeks after weaning a diet supplemented or not with a mix of a low dose (0.1%) of functional amino acids (L-arginine, L-leucine, L-valine, L-isoleucine, L-cystine) and 100 ppm of a polyphenol-rich extract from grape seeds and skins. The mix of amino acids and polyphenols improved growth and feed efficiency. These beneficial effects were associated with a lower microbiota diversity and a bloom of Lactobacillaceae in the jejunum content while the abundance of Proteobacteria was reduced in the caecum content. The mix of amino acids and polyphenols also increased the production by the caecum microbiota of short-chain fatty acids (butyrate, propionate) and of metabolites derived from amino acids (branched-chain fatty acids, valerate, putrescine) and from polyphenols (3-phenylpropionate). Experiments in piglet jejunum organoids revealed that the mix of amino acids and polyphenols upregulated the gene expression of epithelial differentiation markers while it reduced the gene expression of proliferation and innate immunity markers. In conclusion, the supplementation of a mix of amino acids and polyphenols is a promising nutritional strategy to manage gut health in piglets through the modulation of the gut microbiota and of the epithelial barrier.

Use of low dosage amino acid blends to prevent stress-related piglet diarrhea

Weaning is a challenging period for piglets associated with reduced feed intake, impairment of gut integrity, and diarrhea. Previous studies demonstrate that supplementation with single functional amino acids (AA) promote piglets' performance due to the improvement of intestinal health. Thus, we hypothesized that a combination of functional AA provided beyond the postulated requirement for growth could facilitate the weaning transition. Ninety piglets, initially stressed after weaning by 100 min overland transport, received a control diet or the same diet supplemented with a low-dosed (0.3%) mixture of AA (AAB-1: L-arginine, L-leucine, L-valine, L-isoleucine, L-cystine; AAB-2: L-arginine, L-leucine, L-valine, L-isoleucine, L-cystine, and L-tryptophan) for 28 days. Fecal consistency was ranked daily, growth performance was assessed weekly. On days 1 and 14 of the trial, blood samples were collected from a subset of 10 piglets per group to assess concentrations of insulin-like growth factor 1. After 28 days of feeding, tissues were obtained from the same piglets to analyze gut morphology and relative mRNA expression of genes related to gut function. Even if the stress response as indicated by rectal temperature was not different between the groups, pigs supplemented with AAB-2 showed firmer feces after weaning and less days with diarrhea compared to control. Furthermore, the jejunal expression of the MUC-2 gene was reduced (P < 0.05) in group AAB-2. Both AA mixtures increased crypt depth in the duodenum. Collectively, the given results indicate that 0.3% extra AA supplementation might alleviate postweaning diarrhea but did not alter growth performance of weanling piglets.

Assessment of Biolog EcoplateTM method for functional metabolic diversity of aerotolerant pig fecal microbiota

Abstract

In the last decades, gut microbiota and its role in mammal host development and health have been increasingly investigated. Metabolites produced by gut microbiota can affect intestinal homeostasis and immune system maturity and activation, and in turn, they can influence the health and growth performance of livestock. Therefore, a better understanding of the functional metabolic capability of the gut microbiota would be appreciated by the scientific community. In this study, the Biolog^TM Ecoplates technology was applied for studying the metabolic potential of the aerotolerant microbial community of pig fecal samples, evaluating the interference of different storage conditions and cell concentrations. The length of time for which a fecal sample maintained detectable and unchanged microbial metabolic activity was also investigated. Two assays aimed to evaluate differences in the metabolic activities between fresh and snap-frozen fecal samples at different dilutions and at different lengths of times of preservation at −80°C were carried out. The biodiversity and the predicted functionality of the entire bacterial community through a targeted metagenomic approach were also explored. The results highlighted that snap freezing of fecal samples preserved the metabolic activity of the microbial community when compared to fresh feces. Sample storage at −80 °C did not significantly affect the metabolic activity of the microbial community, which was stable for 150 days. Furthermore, the highest metabolic activity was detected with 1:2 to 1:5 dilutions of the stock suspension. Biolog^TM Ecoplates technology is a rapid and useful method to explore microbial communities’ metabolism in animal fecal samples contributing to investigate host animal physiology.

Key points

• Freezing of samples can preserve the functional activity of the aerotolerant microbial community for 150 days.

• The concentration of microbial cells strongly influences metabolic activity detection.

• Sequencing coupled with the Biolog^TMEcoplates could be a strategy to evaluate the metabolic potential of the microbiota of the fecal sample.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00253-021-11449-x.

A longer adaptation period to a functional amino acid-supplemented diet improves growth performance and immune status of Salmonella Typhimurium-challenged pigs

We recently showed that dietary supplementation with key functional amino acids (FAA) improves growth performance and immune status of Salmonella Typhimurium (ST)-challenged pigs. It is not known if ST-challenged pigs will benefit from a longer adaptation period to FAA. The objective of this study was to evaluate the effects of different adaptation periods to diets containing FAA above requirements for growth on performance and immune response of weaned pigs subsequently challenged with ST. A total of 32 mixed-sex weanling pigs (11.6 ± 0.3 kg) were randomly assigned to 1 of 4 dietary treatments, being a basal amino acid (AA) profile fed throughout the experimental period (FAA-) or a functional AA profile (FAA+; Thr, Met, and Trp at 120% of requirements) fed only in the postinoculation (FAA+0), for 1 wk pre- and postinoculation (FAA+1), or throughout the experimental period (FAA+2). After a 14-d adaptation period, pigs were inoculated with ST (2.15 × 109 CFU/mL). Growth performance, body temperature, fecal score, acute-phase proteins, oxidant/antioxidant balance, score for ST shedding in feces and intestinal colonization, and fecal and digesta myeloperoxidase (MPO) were measured pre- and postinoculation. Postinoculation body temperature and fecal score, serum haptoglobin, plasma superoxide dismutase (SOD), malondialdehyde (MDA), and fecal MPO were increased while serum albumin and plasma reduced glutathione (GSH):oxidized glutathione (GSSG) were reduced compared to pre-inoculation (P < 0.05). Average daily gain and G:F were greater in FAA+2 pigs compared to FAA- pigs (P < 0.05). Serum albumin was higher in FAA+2 and FAA+1 compared to FAA+0 and FAA- pigs (P < 0.05) while FAA+2 pigs had lower haptoglobin compared to FAA- (P < 0.05). Plasma SOD was increased and GSH:GSSG was decreased in FAA- pigs compared to the other treatments (P < 0.05). Score for ST shedding in feces was progressively lower from d 1 to 6 regardless of treatment (P < 0.05) and was lower in FAA+2 pigs compared to FAA- and FAA+0 (P < 0.05). Counts of ST in colon digesta were higher in FAA- and FAA+0 pigs compared to FAA+2 (P < 0.05). Fecal and colonic digesta MPO were lower in FAA+2 and FAA+1 pigs compared to FAA- (P < 0.05). These results demonstrate a positive effect of a longer adaptation period to FAA-supplemented diets on performance and immune status of weaned pigs challenged with Salmonella.

Selection for feed efficiency elicits different postprandial plasma metabolite profiles in response to poor hygiene of housing conditions in growing pigs

This study was conducted to compare postprandial plasma concentrations of insulin, energy-related metabolites, and amino acids measured after a 6-week challenge consisting of exposure to good or poor hygiene of housing conditions of 24 growing pigs divergently selected for low-RFI (LRFI) and high-RFI (HRFI). Blood indicators of immune responses were assessed from samples collected before 0 (W0), and 3 (W3), and 6 weeks (W6) after pigs transfer to their respective hygiene of housing conditions. Plasma haptoglobin concentrations and blood neutrophil granulocyte numbers were greater in poor than in good hygiene of housing conditions at W3. Plasma concentrations of total immunoglobulin G were greater (p = 0.04) in poor than in good hygiene of housing conditions at W6. At W6, pigs were fitted with an intravenous catheter for serial blood samplings. Low-RFI pigs had greater insulin (p < 0.001) and lower triglyceride (p = 0.04) average plasma concentrations than HRFI pigs in both conditions. In poor hygiene of housing conditions, the peaks of insulin and glucose were observed earlier and that of insulin was greater in LRFI than in HRFI pigs. Irrespective of genetic line, average plasma concentrations of histidine, isoleucine, leucine, methionine, threonine, valine, and alanine were greater in poor compared with good hygiene of housing conditions. Only HRFI pigs had greater lysine, asparagine, proline, and tyrosine plasma concentrations in poor than in good hygiene of housing conditions. Conversely, arginine, tryptophan, proline, and tyrosine plasma concentrations were lower only for LRFI pigs housed in poor hygiene conditions. Our results suggest that, contrary to HRFI, LRFI pigs increase or maintain their utilization of tryptophan, arginine, and lysine when housed in poor hygiene conditions. This indicates that this difference may contribute to the better capacity of LRFI to cope with poor hygiene of housing conditions.

Amino Acids in Swine Nutrition and Production

Amino acids are the building blocks of proteins in animals, including swine. With the development of new analytical methods and biochemical research, there is a growing interest in fundamental and applied studies to reexamine the roles and usage of amino acids (AAs) in swine production. In animal nutrition, AAs have been traditionally classified as nutritionally essential (EAAs) or nutritionally nonessential (NEAAs). AAs that are not synthesized de novo must be provided in diets. However, NEAAs synthesized by cells of animals are more abundant than EAAs in the body, but are not synthesized de novo in sufficient amounts for the maximal productivity or optimal health (including resistance to infectious diseases) of swine. This underscores the conceptual limitations of NEAAs in swine protein nutrition. Notably, the National Research Council (NRC 2012) has recognized both arginine and glutamine as conditionally essential AAs for pigs to improve their growth, development, reproduction, and lactation. Results of recent work have also provided compelling evidence for the nutritional essentiality of glutamate, glycine, and proline for young pigs. The inclusion of so-called NEAAs in diets can help balance AAs in diets, reduce the dietary levels of EAAs, and protect the small intestine from oxidative stress, while enhancing the growth performance, feed efficiency, and health of pigs. Thus, both EAAs and NEAAs are needed in diets to meet the requirements of pigs. This notion represents a new paradigm shift in our understanding of swine protein nutrition and is transforming pork production worldwide.

Functional amino acid supplementation, regardless of dietary protein content, improves growth performance and immune status of weaned pigs challenged with Salmonella Typhimurium

High dietary protein may increase susceptibility of weaned pigs to enteric pathogens. Dietary supplementation with functional amino acids (FAA) may improve growth performance of pigs during disease challenge. The objective of this study was to evaluate the interactive effects of dietary protein content and FAA supplementation above requirements for growth on performance and immune response of weaned pigs challenged with Salmonella. Sixty-four mixed-sex weanling pigs (13.9 ± 0.82 kg) were randomly assigned to dietary treatments in a 2 × 2 factorial arrangement with low (LP) or high protein (HP) content and basal (AA-) or FAA profile (AA+; Thr, Met, and Trp at 120% of requirements) as factors. After a 7-d adaptation period, pigs were inoculated with either a sterile saline solution (CT) or saline solution containing Salmonella Typhimurium (ST; 3.3 × 109 CFU/mL). Growth performance, body temperature, fecal score, acute-phase proteins, oxidant/antioxidant balance, ST shedding score in feces and intestinal colonization, fecal and digesta myeloperoxidase (MPO), and plasma urea nitrogen (PUN) were measured pre- and postinoculation. There were no dietary effects on any measures pre-inoculation or post-CT inoculation (P > 0.05). Inoculation with ST increased body temperature and fecal score (P < 0.05), serum haptoglobin, plasma superoxide dismutase (SOD), malondialdehyde (MDA), PUN, and fecal MPO, and decreased serum albumin and plasma reduced glutathione (GSH):oxidized glutathione (GSSG) compared with CT pigs (P < 0.05). ST-inoculation reduced average daily gain (ADG) and feed intake (ADFI) vs. CT pigs (P < 0.05) but was increased by AA+ vs. AA- in ST pigs (P < 0.05). Serum albumin and GSH:GSSG were increased while haptoglobin and SOD were decreased in ST-inoculated pigs fed AA+ vs. AA- (P < 0.05). PUN was higher in HP vs. LP-fed pigs postinoculation (P < 0.05). Fecal ST score was increased in ST-inoculated pigs on days 1 and 2 postinoculation and declined by day 6 (P < 0.05) in all pigs while the overall score was reduced in AA+ vs. AA- pigs (P < 0.05). Cecal digesta ST score was higher in HP vs. LP-fed pigs and were lower in AA+ compared with AA- fed pigs in the colon (P < 0.05). Fecal and digesta MPO were reduced in ST pigs fed AA+ vs. AA- (P < 0.05). These results demonstrate a positive effect of FAA supplementation, with minimal effects of dietary protein, on performance and immune status in weaned pigs challenged with Salmonella.

Yellow emission N-doped fluorescent carbon dots as fluorescent nanoprobes for the detection of L-threonine in real samples

High quantum yield carbon dots and their applications in the detection of L-threonine.

Impacts of Amino Acids on the Intestinal Defensive System

The intestine interacts with a diverse community of antigens and bacteria. To keep its homeostasis, the gut has evolved with a complex defense system, including intestinal microbiota, epithelial layer and lamina propria. Various factors (e.g., nutrients) affect the intestinal defensive system and progression of intestinal diseases. This review highlights the current understanding about the role of amino acids (AAs) in protecting the intestine from harm. Amino acids (e.g., arginine, glutamine and tryptophan) are essential for the function of intestinal microbiota, epithelial cells, tight junction, goblet cells, Paneth cells and immune cells (e.g., macrophages, B cells and T cells). Through the modulation of the intestinal defensive system, AAs maintain the integrity and function of the intestinal mucosa and inhibit the progression of various intestinal diseases (e.g., intestinal infection and intestinal colitis). Thus, adequate intake of functional AAs is crucial for intestinal and whole-body health in humans and other animals.

Toward better estimates of the real-time individual amino acid requirements of growing-finishing pigs showing deviations from their typical feeding patterns

Pigs exposed to stressors might change their daily typical feeding intake pattern. The objective of this study was to develop a method for the early identification of deviations from an individual pig's typical feeding patterns. In addition, a general approach was proposed to model feed intake and real-time individual nutrient requirements for pigs with atypical feeding patterns. First, a dynamic linear model (DLM) was proposed to model the typical daily feed intake (DFI) and daily gain (DG) patterns of pigs. Individual DFI and DG dynamics are described by a univariate DLM in conjunction with Kalman filtering. A standardized tabular cumulative sum (CUMSUM) control chart was applied to the forecast errors generated by DLM to activate an alarm when a pig showed deviations from its typical feeding patterns. The relative feed intake (RFI) during a challenge period was calculated. For that, the forecasted individual pig DFI is expressed as its highest DFI relative to the intake during pre-challenge period. Finally, the DLM and RFI approaches were integrated into the actual precision-feeding model (original model) to estimate real-time individual nutrient requirements for pigs with atypical feeding patterns. This general approach was evaluated with data from two studies (130 pigs, at 35.25 ± 3.9 kg of initial BW) that investigated during 84 days the effect of precision-feeding systems for growing-finishing pigs. The proposed general approach to estimating real-time individual nutrient requirements (updated model) was evaluated by comparing its estimates with those generated by the original model. For 11 individuals out of 130, the DLM did not fit the observed data well in a specific period, resulting in an increase in the sum of standardized forecast errors and in the number of time steps that the model needed to adapt to the new patterns. This poor fit can be identified by the increase in the CUMSUM with a consequent alarm generated. The results of this study show that the updated model made it possible to reduce intra-individual variation for the estimated lysine requirements in comparison with the original model, especially for individuals with atypical feeding patterns. In conclusion, the DLM in conjunction with CUMSUM could be used as a tool for the online monitoring of DFI for growing-finishing pigs. Moreover, the proposed general approach allows the estimation of real-time amino acid requirements and accounts for the reduced feed intake and growth potential of pigs with atypical feeding patterns.

Diet complexity and l-threonine supplementation: effects on nutrient digestibility, nitrogen and energy balance, and body composition in nursery pigs

This study was conducted to investigate the effects of dietary complexity and l-Thr supplementation on energy and nutrient utilization in nursery pigs. Thirty-two nursery pigs (7.23 ± 0.48 kg) were randomly assigned to a 2 × 2 factorial treatment arrangement based on diet complexity (complex vs. simple) with different levels of l-Thr supplementation. The complex diet contained animal protein sources (e.g., fish meal and plasma) and a dairy product (e.g., dried whey) to mimic a conventional nursery diet. The simple diet was formulated with corn, wheat, and soybean meal. Both diets were supplemented with l-Thr to contain either 100% or 115% (SUP Thr) of the estimated standardized ileal digestible Thr requirement for 9 kg body weight pigs (NRC, 2012). The pigs were individually housed in metabolism crates and fed an experimental diet ad libitum for a 7-d adaptation period and 5 d of total but separate urine and fecal collection. On day 14, all pigs were euthanized to determine body composition. The diet complexity, l-Thr supplementation, and their interactions were considered main effects. Pigs fed the complex diet tended to exhibit greater (P < 0.10) apparent total tract digestibility (ATTD) of ash and urinary energy output than those fed the simple diet. The complex diet had greater (P < 0.05) digestible energy and net energy contents than the simple diet. Furthermore, the complex diet-fed pigs had lower (P < 0.05) plasma urea nitrogen concentration on day 14 than simple diet-fed pigs. The SUP Thr decreased (P < 0.05) ATTD of acid detergent fiber but trended (P < 0.10) toward a decrease in urinary nitrogen (N) output and an increase in N retention and body N mass. In conclusion, the simple diet for nursery pigs had lower digestible and net energy contents than a complex diet. The SUP Thr can improve N utilization and body protein deposition, irrespective of diet complexity.

Composition of amino acids and related nitrogenous nutrients in feedstuffs for animal diets

We analyzed the composition of amino acids (AAs) in oligopeptides, proteins, and the free pool, as well as creatine, agmatine, polyamines, carnosine, anserine, and glutathione, in animal- and plant-derived feedstuffs. Ingredients of animal origins were black soldier fly larvae meal (BSFM), chicken by-product meal, chicken visceral digest, feather meal, Menhaden fishmeal, Peruvian anchovy fishmeal, Southeast Asian fishmeal, spray-dried peptone from enzymes-treated porcine mucosal tissues, poultry by-product meal (pet-food grade), spray-dried poultry plasma, and spray-dried egg product. Ingredients of plant origins were algae spirulina meal, soybean meal, and soy protein concentrate. All animal-derived feedstuffs contained large amounts of all proteinogenic AAs (particularly glycine, proline, glutamate, leucine, lysine, and arginine) and key nonproteinogenic AAs (taurine and 4-hydroxyproline), as well as significant amounts of agmatine, polyamines, creatine, creatinine, creatine phosphate, and glutathione. These nitrogenous substances are essential to either DNA and protein syntheses in cells or energy metabolism in tissues (particularly the brain and skeletal muscle). Of note, chicken by-product meal, poultry by-product meal, and spray-dried poultry plasma contained large amounts of carnosine and anserine (potent antioxidants). Compared with most of the animal-derived feedstuffs, plant-derived feedstuffs contained much lower contents of glycine and proline, little 4-hydroxyproline, and no creatine, creatinine, creatine phosphate, carnosine or anserine. These results indicate the unique importance of animal-source feedstuffs in improving the feed efficiency, growth and health of animals (including fish and companion animals). Because soy protein concentrate is consumed by infants, children and adults, as are BSFM and algae for children and adults, our findings also have important implications for human nutrition.

Dose-response of different dietary leucine levels on growth performance and amino acid metabolism in piglets differing for aminoadipate-semialdehyde synthase genotypes

Dose-response studies of dietary leucine (Leu) in weaners are needed for a proper diet formulation. Dietary Leu effect was assessed in a 3-weeks dose-response trial with a 2 (genotype) x 5 (diets) factorial arrangement on one-hundred weaned pigs (9 to 20 kg body weight (BW)). Pigs differed for a polymorphism at the aminoadipate-semialdehyde synthase (AASS) gene, involved in lysine (Lys) metabolism. Pigs received experimental diets (d7 to d28) differing for the standardized ileal digestible (SID) Leu:Lys: 70%, 85%, 100%, 115%, 130%. Daily feed intake (ADFI), daily gain (ADG) and feed:gain (F:G) in all pigs and ADG and F:G in two classes of BW were analyzed using regression analysis with curvilinear-plateau (CLP) and linear quadratic function (LQ) models. Amino acid (AA) concentrations in plasma, liver, muscle and urine were determined. AASS genotype did not affect the parameters. Dietary Leu affected performance parameters, with a maximum response for ADG and F:G between 100.5% and 110.7% SID Leu:Lys, higher than the usually recommended one, and between 110.5% and 115.4% and between 94.9% and 110.2% SID Leu:Lys for ADG for light and heavy pigs respectively. AA variations in tissues highlighted Leu role in protein synthesis and its influence on the other branched chain AAs.

Postprandial insulin and nutrient concentrations in lipopolysaccharide-challenged growing pigs reared in thermoneutral and high ambient temperatures1

The aim of this study was to evaluate the associated effects of ambient temperature and inflammation caused by repeated administration of Escherichia coli lipopolysaccharide (LPS) on insulin, energy, and AA metabolism. Twenty-eight pigs were assigned to one of the two thermal conditions: thermoneutral (24 °C) or high ambient temperature (30 °C). The experimental period lasted 17 d, which was divided into a 7-d period without LPS (days -7 to -1), and a subsequent 10-d LPS period (days 1 to 10) in which pigs were administered 5 repeated injections of LPS at 2-d intervals. Postprandial profiles of plasma insulin and nutrients were evaluated through serial blood samples taken on days -4 (P0), 4 (P1), and 8 (P2). Before the LPS-challenge (P0), postprandial concentrations of glucose, lactate, Gln, Ile, Leu, Phe, Tyr, and Val were greater in pigs kept at 24 °C than at 30 °C (P < 0.05). In contrast, Arg, Asp, Gly, His, and Met postprandial concentrations at P0 were lower at 24 °C than at 30 °C (P < 0.05). At both 24 and 30 °C conditions, pigs had greater postprandial concentrations of insulin (P < 0.01) and lower concentrations of NEFA (P < 0.01) and α-amino nitrogen (P < 0.05) at P1 and P2 than at P0. Compared with P0, postprandial concentrations of glucose were greater (P < 0.05) at P1 in pigs kept at 24 °C, and at P1 and P2 in pigs kept at 30 °C. At both ambient temperatures, pigs had lower (P < 0.05) postprandial concentrations of Ala, Gly, His, Ile, Leu, Pro, Ser, Thr, Trp, and Val at P1 and P2 than at P0. Arginine postprandial concentration at P1 was lower than at P0 in pigs kept at 24 °C (P < 0.05), whereas no difference was observed in pigs at 30 °C. Relative to P0, Gln and Tyr concentrations were lower at P1 and P2 in pigs kept at 24 °C (P < 0.01), whereas lower Gln concentration was observed only at P2 (P < 0.01) and lower Tyr only at P1 (P < 0.01) in pigs kept at 30 °C. Our study shows a hyperglycemic and hyperinsulinemic state in LPS-challenged pigs and a greater magnitude of this response in pigs kept at 30 °C. Furthermore, LPS caused important changes in BCAA, His, Thr, and Trp profiles, suggesting the role these AA in supporting the inflammatory response. Finally, our results suggest that LPS-induced effects on postprandial profiles of specific AA (Arg, Gln, Phe, and Tyr) may be modulated by ambient temperature.

Methodology and application of Escherichia coli F4 and F18 encoding infection models in post-weaning pigs

The enterotoxigenic Escherichia coli (ETEC) expressing F4 and F18 fimbriae are the two main pathogens associated with post-weaning diarrhea (PWD) in piglets. The growing global concern regarding antimicrobial resistance (AMR) has encouraged research into the development of nutritional and feeding strategies as well as vaccination protocols in order to counteract the PWD due to ETEC. A valid approach to researching effective strategies is to implement piglet in vivo challenge models with ETEC infection. Thus, the proper application and standardization of ETEC F4 and F18 challenge models represent an urgent priority. The current review provides an overview regarding the current piglet ETEC F4 and F18 challenge models; it highlights the key points for setting the challenge protocols and the most important indicators which should be included in research studies to verify the effectiveness of the ETEC challenge.

Based on the current review, it is recommended that the setting of the model correctly assesses the choice and preconditioning of pigs, and the timing and dosage of the ETEC inoculation. Furthermore, the evaluation of the ETEC challenge response should include both clinical parameters (such as the occurrence of diarrhea, rectal temperature and bacterial fecal shedding) and biomarkers for the specific expression of ETEC F4/F18 (such as antibody production, specific F4/F18 immunoglobulins (Igs), ETEC F4/F18 fecal enumeration and analysis of the F4/F18 receptors expression in the intestinal brush borders). On the basis of the review, the piglets’ response upon F4 or F18 inoculation differed in terms of the timing and intensity of the diarrhea development, on ETEC fecal shedding and in the piglets’ immunological antibody response. This information was considered to be relevant to correctly define the experimental protocol, the data recording and the sample collections. Appropriate challenge settings and evaluation of the response parameters will allow future research studies to comply with the replacement, reduction and refinement (3R) approach, and to be able to evaluate the efficiency of a given feeding, nutritional or vaccination intervention in order to combat ETEC infection.