Thr Requirement Research Articles

Dietary threonine influences antioxidant capacity and immune status in juvenile largemouth bass (Micropterus salmoides)

As a restricted amino acid, threonine (Thr) deficiency reduces antioxidant and immune capacity in fish. In the present study, six diets containing different Thr levels (1.39 %, 1.71 %, 1.95 %, 2.28 %, 2.58 %, and 2.65 %) were fed to largemouth bass (15±0.1 g) for 60 days. The present results showed that neither growth nor whole-body composition was affected by different Thr levels. And low dietary Thr levels (1.39 %) significantly decreased serum total protein (TP) and albumin (ALB) levels, but increased alkaline phosphatase (ALP) levels. And 1.39 % Thr diet significantly decreased liver catalase (CAT) activity but increased malonaldehyde (MDA) levels, and the maximum total antioxidant capacity (T-AOC) was observed in response to the 1.95 % Thr diet. Liver proapoptotic factors (bax and caspase9) were significantly elevated in fish fed the 1.39 % Thr diet. The nuclear factor κB (nf-κb) and the NF-κB-mediated inflammatory cytokines were significantly increased in fish fed the 1.39 % Thr diet. The mRNA levels of protein kinase R (PKR)-like endoplasmic reticulum kinase (perk), eukaryotic translation initiation factor 2 (eif2α), activating transcription factor 4 (atf4), and C/EBP-homologous protein (chop), which are factors in the PERK/ATF4/CHOP pathway, one of the unfolded protein response (UPR) signaling pathways, were significantly increased by the 1.39 % Thr diet. The present study showed that low dietary Thr levels caused oxidative damage, reduced immunity, might affected PERK-ATF4-CHOP signaling to induce apoptosis, and via NF-κB signaling to trigger an inflammatory response in largemouth bass. Based on the TP, ALB, CAT, and MDA levels, the dietary Thr requirements for juvenile largemouth bass were estimated to be 2.18 %, 2.29 %, 1.92 %, and 1.88 %. Furthermore, these findings provided a new perspective that low dietary amino acid levels may trigger apoptosis and inflammatory responses in fish through the UPR signaling pathway.

PSV-17 Threonine Requirements for Post-Weaning Pig in Individual Precision Nutrition Programs: a Meta-Analysis

Abstract Threonine (Thr) is generally the second limiting amino acid (AA) in growing pig diets, and it has a vital role in supporting intestinal functions and the immune system. Additionally, providing pigs with the correct AA requirements decreases nitrogen excretion and improves growth performance. This study aimed to determine standardized ileal digestibility (SID) Thr requirements for individual post-weaned pigs. Additionally, the Thr supplementation effect on average daily gain (ADG) of weaning and growing [7.3 – 51.5 kg of body weight (BW)] pigs under a sanitary challenge was evaluated. Eleven papers published from 1993 to 2015 composed the dataset used to determine the SID Thr requirement in the nursery phase, and five studies conducted from 2014 to 2020 composed the enteric sanitary challenge dataset. The SID Thr was obtained from publications when available or estimated based on the ingredient composition using EvaPig software. The average individual pig SID Thr requirements were estimated by bootstrapping 1,000 repetitions of a linear-plateau mixed model where all parameters were considered random as a function of the trial code. A general positive-definite matrix was used to represent the between-factors covariance using the nlme package of the R software. The effect of supplementing SID Thr above the requirement to attenuate ADG losses during a challenge was evaluated by an effect size analysis using a mixed model of the R Metafor package. Due to the low number of studies assessing pigs’ response to enteric challenges, a P < 0.25 was considered significant. In the post-weaning (14 kg average BW), the estimated ADG was 457 g/d (411 to 493 g/d) as a function of SID Thr individual requirement, which was 4.71 g/d for the average pig, with the least demanding pig requiring 4.4 g/d and the most demanding one requiring 5.1 g/d. For challenged pigs, the across-study heterogeneity was moderate (Higgs index = 36%). Increasing Thr intake by 18% above the estimated requirement attenuated (P = 0.15) ADG losses by 0.7 standard deviations (60 g) compared with pigs fed diets meeting Thr requirements. For pigs in individual precision feeding, the SID Thr requirement is estimated to be 1.03 g per 100 g of ADG for post-weaned pigs. The increase of SID Thr intake by 18% attenuated the ADG losses by 19% compared with non-supplemented pigs with enteric challenges.

Dietary threonine and lysophospholipid supplement in broiler chickens: effect on productive performance, carcass variables, cecal microbiota activity, and jejunal morphology.

The objective of this experiment was to investigate the efficacy of lysophospholipid (LPL) in combination with different levels of threonine (Thr) on productive performance, jejunal morphometric variables, cecal microbial population, and carcass characteristics of male broiler chickens. Four hundred 1-day-old male broiler chicks were distributed into eight experimental groups with five replicates, each of ten birds. Factors were two levels of 0 or 0.1% Lipidol as LPL supplement and four inclusion amount of Thr (100, 105, 110, or 115% of requirements) in the diets. During 1 to 35days, inclusion of LPL supplementation in diets improved the body weight gain (BWG) and feed conversion ratio (FCR) of broilers (P < 0.05). Besides, FCR was significantly greater in the birds fed with 100% Thr compared to the other inclusion rates of Thr (P < 0.05). The jejuna villus length (VL) and crypt depth (CD) were greater in the birds fed with LPL-supplemented diets (P < 0.05) while the greatest VH/CD and villus surface was observed in the birds fed with 105% of dietary Thr (P < 0.05). In cecal microbiota composition, Lactobacillus population was lower in broilers which received diet containing 100% Thr compared to the other group receiving more than 100% Thr (P < 0.05). In conclusion, inclusion of LPL supplements and amounts greater than Thr requirement in diet improved productive performance and jejunal morphology of male broiler chickens.

The dietary requirement for threonine in juvenile olive flounder (Paralichthys olivaceus)

This study was conducted to determine dietary threonine (Thr) requirement for juvenile olive flounder (Paralichthys olivaceus). A total of 450 juvenile fish (23.2 ± 0.4 g) were randomly distributed to 18 tanks (215 L) with 25 fish per tank. Experimental diets included with graded levels of Thr at 0.0%, 0.4%, 0.8%, 1.2%, 1.6%, and 2.0% were assigned for triplicate groups of fish and fed two times daily to apparent satiation for 12 weeks. Weight gain, specific growth rate, feed intake, feed utilization and survival were significantly (p &lt; 0.05) increased in fish fed with dietary Thr levels over 0.8%, and no significant differences were observed between 0.8% to 2.3% levels. Non-specific immune parameters of serum lysozyme, myeloperoxidase activity, antiprotease activity, and total immunoglobulin were significantly increased by dietary Thr over 0.8%. Based on the broken-line regression analysis, the Thr requirement for the optimum growth and immune response in olive flounder is likely to be 1.03% in the diet.

Physiological Functions of Threonine in Animals: Beyond Nutrition Metabolism.

Threonine (Thr), an essential amino acid for animals and the limiting amino acid in swine and poultry diets, which plays a vital role in the modulation of nutritional metabolism, macromolecular biosynthesis, and gut homeostasis. Current evidence supports that the supplementation of Thr leads to benefits in terms of energy metabolism. Threonine is not only an important component of gastrointestinal mucin, but also acts as a nutritional modulator that influences the intestinal immune system via complex signaling networks, particularly mitogen-activated protein kinase (MAPK) and the target of the rapamycin (TOR) signal pathway. Threonine is also recognized as an indispensable nutrient for cell growth and proliferation. Hence, optimization of Thr requirement may exert a favorable impact on the factors linked to health and diseases in animals. This review focuses on the latest reports of Thr in metabolic pathways and nutritional regulation, as well as the relationship between Thr and relevant physiological functions.

The optimum threonine requirement in diets of juvenile hybrid grouper ( epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂ )

A six-week growth trial was conducted to evaluate the optimum threonine (Thr) requirement in diets of juvenile hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂). Six isoenergetic, isoproteic and isolipidic diets were formulated to contain 5.4, 7.5, 10.3, 11.5, 13.7 and 15.2 g/kg dry matter dietary Thr levels. Results showed that and fish fed 5.4 g/kg dietary Thr had the lowest weight gain percentage (WG%) or protein productive value (PPV) among all experimental treatments. Analysis by the quadratic regression indicated that the optimum Thr requirement for maximum WG% or PPV in diets for hybrid grouper was estimated to be 11.48 or 13.55 g/kg of dry matter. The mRNA expression of hepatic growth hormone receptor 1 (GHR1) in fish fed 11.5 and 13.7 g/kg dietary Thr was higher than that of fish fed other dietary Thr levels. Fish fed 5.4 g/kg dietary Thr had the lowest whole-body protein contents and the lowest expression of hepatic target of rapamycin (TOR), ribosomal protein S6 kinase 1 (S6 K1) among all experimental groups. In conclusion, the optimum dietary Thr requirement for best growth of hybrid grouper was estimated to be 11.48 g/kg dry matter (corresponding to 23.27 g/kg dietary protein).

Nutritional requirement of meat-type Japanese quail: Threonine

Threonine (Thr), the third limiting amino acid in conventional poultry diets, plays a vital role in growth performance and immunocompetence of gastrointestinal tract and tissue protection. A dose-response experiment was conducted to estimate the Thr requirements of growing meat-type Japanese quail using growth performance parameters as response criteria and estimating the break-point as the minimum requirement by fitting different broken line models into the data. Five increments of Thr including 7.38, 8.38, 9.38, 10.38, and 11.38 g Thr/kg of diet were used from 7 to 21 days of age. in the second and third week of age. A total of 375, 7-day old quail chicks were randomly allotted to one of five experimental diets each with 5 replicate pens each and 15 birds per pen. Feed intake (FI), weight gain (WG), feed conversion ratio (FCR), dressing (DRS), breast meat yield (BMY), thigh meat yield (TMY), and relative weight of bursa of Fabricius (BURS) were measured and used to fit regression models. Depending on different broken line models, the Thr requirements for optimum WG, FCR, TMY, DRS, and BURS ranged from 8.68 to 11.36, 10.25–10.38, 7.35–8.05, 10.16–10.33, and 9.38–10.71 g/kg of diet, respectively. The highest required amount of Thr was for WG (11.36 g/kg) followed by BURS (10.71 g/kg) and FCR (10.38 g/kg) using broken line models. Desirability function analysis for performance estimated the maximum WG and lowest FCR at 11.38 g Thr/kg of diet. Principal component analysis showed that FCR had the highest correlation with dietary Thr followed by WG. The moderate high eigenvalue of BURS provides evidence for immunocompetence contribution of dietary Thr in growing quail. Based on this experiment, the higher levels of Thr titrations may be needed than 11.38 g/kg to fit spline models. Overall, the estimated Thr by desirability function would be more reliable estimation than those estimated by broken line models.

PSXI-31 Program Chair Poster Pick: Determination of the threonine requirement in adult and senior Labrador Retrievers using the indicator amino acid oxidation technique

Abstract Although nutrient profiles for canines have been developed in the past, the need to update amino acid (AA) requirements has gained importance as genetic selection changes the recommended nutrients. Correctly feeding AA to canines can have enormous effects, considering a deficiency or excess of such nutrient can lead to weight loss, disease, or in some cases, death. Amino acid requirements can be determined through the nitrogen balance or indicator amino acid oxidation (IAAO) methods. In this experiment, the IAAO technique was used to determine the threonine (Thr) requirement in Labrador retrievers. A total of six dogs (6 adult and 6 senior) were subjected to six diets with varying levels of Thr, ranging from deficient to excess. Diets were formulated to 1.6x NRC values for all indispensable amino acids. The control diet was fed for two days, followed by a day in which the test diet was fed, a tracer AA was supplied, and breath samples were collected. On test day, a priming dose of L-[1-13C]phenylalanine (Cambridge Isotope Laboratories, Inc.) based on the subject’s body weight was first supplied, followed by [1-13C]Phe doses every thirty minutes, spanning a four hour period. A respiration mask was placed on each subject every thirty minutes (Oxymax, Columbus Instruments), 13CO2 was collected, and enrichment was determined by isotope ratio mass spectrometry (IRMS). Results for IRMS were converted to atom percent excess (APE) and analyzed using a piecewise model of best fit (JMP® Pro 15). The segmented line regression showed that the Thr mean and population requirements were determined to be 1.21 ± 0.24 and 0.92 ± 0.17 g/1000kcal (mean ± 2SD) for adult and senior dogs, respectively. As the pet food industry becomes more specialized in diets relating to aging, and diseased canines, updating the amino acid requirements related to such animals is increasingly important.

Intestinal Health and Threonine Requirement of Growing Pigs Fed Diets Containing High Dietary Fibre and Fermentable Protein

Simple SummaryDietary components, such as fibre and protein, have significant impacts on nutrient requirements and intestinal health in pigs. The objectives of this study were to investigate the interactive effects of dietary fibre and fermentable protein on threonine requirement for protein deposition in growing pigs and to determine how these factors affect markers of intestinal health. In this study we used the nitrogen-balance approach to study the influence of high protein diets combined with high fibre on threonine requirement for protein deposition. We further used gene expression, fermentation metabolites (short and branched chain fatty acid concentration), and serum antioxidant status in these pigs as markers of intestinal health and function. We demonstrate that high fibre will indeed increase threonine requirement for protein deposition but can mitigate the negative effects of fermentable protein metabolites on intestinal health. These results will have implications for the development of dietary strategies to improve growth and overall health in pigs, including adjustments to dietary fibre, protein, and amino acid content that maximize pig growth, nutrient utilization, and intestinal health.Dietary fibre (DF) and fermentable crude protein (fCP) are dietary factors which affect nutrient utilization and intestinal health in pigs. A nitrogen (N)-balance study was conducted to determine the impact of DF and fCP on threonine (Thr) requirement for protein deposition (PD) and indicators of intestinal health. A total of 160 growing pigs (25 kg) were randomly assigned to 1 of 20 dietary treatments in a 2 × 2 × 5 factorial arrangement in a randomized complete block design with dietary fibre (low (LF) or high fibre (HF)], fCP [low (LfCP) or high fCP (HfCP)) and Thr (0.52, 0.60, 0.68, 0.76, or 0.82% standardized ileal digestible) as factors. Then, 4-day total urine and fecal collection was conducted, and pigs were euthanized for intestinal tissue and digesta sampling. Feeding high DF, regardless of fCP content, increased Thr requirement for PD (p < 0.05). High fCP, regardless of DF content, reduced Thr requirement for PD. Serum antioxidant capacity increased as dietary Thr level increased (p < 0.05). Cecal digesta short-chain fatty acids (SCFA) increased (p < 0.05) with HF and branched-chain fatty acids (BCFA) increased with HfCP and reduced with HF (p < 0.05). HfCP reduced (p < 0.05) mucin-2 (MUC2) expression in the colon of the HF but not the LF fed pigs and HF increased MUC2 in the LfCP but not the HfCP fed pigs. Feeding HF diet increased (p < 0.05) expression of zonula occludens-1 in the LfCP with no effect on HfCP fed pigs. Ammonia concentration in both cecum and colon increased (p < 0.05) in the HfCP fed pigs. Overall, high DF reduced the negative impact of HfCP on intestinal health, as indicated by alterations in SCFA and BCFA production and gut barrier gene expression. While increased dietary Thr content is required for PD in pigs fed high DF, feeding high fCP reduced Thr requirements.

Diet complexity and l-threonine supplementation: effects on growth performance, immune response, intestinal barrier function, and microbial metabolites in nursery pigs.

The aim of this study was to investigate the effects of diet complexity and l-Thr supplementation level on the growth performance, immune response, intestinal barrier function, and microbial metabolites in nursery pigs. Thirty-two weaned pigs (body weight 7.23 ± 0.48 kg) were randomly assigned to dietary treatments in a 2 × 2 factorial arrangement based on diet complexity (complex or simple) and dietary Thr content. The complex diet contained fish meal, plasma protein, and dried whey to mimic a conventional nursery diet. The simple diet was formulated with corn, wheat, and soybean meal and did not contain any animal products. l-Thr was supplemented to each diet to supply either 100% (STD Thr) or 115% (SUP Thr) of the NRC (2012) requirement for standardized ileal digestible Thr. Pigs were individually housed and fed experimental diets ad libitum for 14 d. Diet complexity, dietary Thr content, and their interactions were considered the main effects. Pigs fed the simple diet had greater (P < 0.05) plasma interleukin (IL)-10 and IL-6 concentrations compared with those fed the complex diet on days 7 and 14, respectively. Simple diet-fed pigs tended to show greater (P < 0.10) expression of genes encoding for tumor necrosis factor-α, claudin-1, and zonula occludens-1 in the jejunum compared with complex diet-fed pigs. The simple diet-fed pigs had greater (P < 0.05) concentrations of NH3-N in the jejunum digesta than did complex diet-fed pigs. The SUP Thr increased (P < 0.05) villus height and goblet cell (GC) density in villi and crypts in the jejunum and deepened (P < 0.05) crypts in the proximal colon. The SUP Thr resulted in the upregulation (P < 0.05) of occludin gene expression and a tendency toward the downregulation (P = 0.10) of IL-6 gene expression in the jejunum. Interactions (P < 0.05) between diet complexity and l-Thr supplementation level were observed in GC density in the crypt, NH3-N concentration in the jejunum, and the contents of acetate, propionate, and total volatile fatty acids in the colon. In conclusion, feeding a simple diet to nursery pigs resulted in systemic and intestinal inflammation. The SUP Thr diet did not normalize the simple diet-induced inflammation but improved gut integrity. SUP Thr seems to have greater benefits with a simple diet than with a complex diet. Therefore, SUP Thr in a simple diet could be a beneficial nutritional strategy for enhancing gut health.

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.

Adult dogs of different breed sizes have similar threonine requirements as determined by the indicator amino acid oxidation technique

Threonine (Thr) requirements for immature (growing) Beagles have been determined, but little knowledge is available on Thr requirements for maintenance in mature dogs. Moreover, differences of Thr requirements among different breeds or sizes of adult dogs have not been investigated. The objective of the present study was to determine Thr requirements in adult dogs of three different breeds using the indicator amino acid oxidation (IAAO) technique. In total, 13 adult dogs were used, 4 Miniature Dachshunds (5.8 ± 0.4 kg body weight [BW]; 3 spayed and 1 neutered), 4 spayed Beagles (9.3 ± 0.6 kg BW), and 5 neutered Labrador Retrievers (30.5 ± 1.7 kg BW). Dogs were fed a Thr-deficient diet (Thr = 0.23%) and randomly allocated to receiving one of seven concentrations of Thr supplementation (final Thr concentration in experimental diets was 0.23%, 0.33%, 0.43%, 0.53%, 0.63%, 0.73%, and 0.83%; as fed basis) for 2 d. After 2 d of adaptation to the experimental diets, dogs underwent individual IAAO studies. During the IAAO studies, total daily feed was divided into 13 equal meals; at the sixth meal, dogs were fed a bolus of l-[1-13C]-Phenylalanine (Phe) (9.40 mg/kg BW), and thereafter, l-[1-13C]-Phe (2.4 mg/kg BW) was supplied with every meal. Before feeding the next experimental diet, dogs were fed a Thr-adequate basal diet for 4 d (Thr = 0.80% as fed basis) in known amounts that maintained individual dog BW. Total production of 13CO2 during isotopic steady state was determined by enrichment of 13CO2 in breath samples and total production of CO2 measured using indirect calorimetry. The mean requirements for Thr, defined as the breakpoint, and the 95% confidence interval (CI) were determined using a two-phase linear regression model. For Miniature Dachshunds, the two-phase model was not significant, and Thr requirements could not be determined. Mean Thr requirements for Beagles and Labradors were 72.2 and 64.1 mg/kg BW on an as-fed basis, respectively. The requirement for Thr between these two dog breeds was not different (P > 0.10). Thus, the data for Beagles and Labradors were pooled and a mean requirement for Thr was determined at 66.9 mg/kg BW, and the 95% CI was estimated at 84.3 mg/kg BW. In conclusion, estimated Thr requirements for Beagles and Labradors did not differ, and these recommendations are higher than those suggested by NRC (2006) and AAFCO (2014) for adult dogs at maintenance.

Effect of dietary threonine on growth performance and muscle growth, protein synthesis and antioxidant-related signalling pathways of hybrid catfish Pelteobagrus vachelli♀ × Leiocassis longirostris♂.

The experiment was conducted to investigate the effects of dietary threonine (Thr) on growth performance and muscle growth, protein synthesis and antioxidant-related signalling pathways of hybrid catfish Pelteobagrus vachelli♀ × Leiocassis longirostris♂. A total of 1200 fish (14·19 (se 0·13) g) were randomly distributed into six groups with four replicates each, fed six diets with graded level of Thr (9·5, 11·5, 13·5, 15·4, 17·4 and 19·3 g/kg diets) for 56 d. Results showed (P < 0·05) that dietary Thr (1) increased percentage weight gain, specific growth rate, feed efficiency and protein efficiency ratio; (2) up-regulated growth hormone (GH), insulin-like growth factor 1 (IGF-1), proliferating cell nuclear antigen, myogenic regulation factors (MyoD, Myf5, MyoG and Mrf4) and myosin heavy chain (MyHC) mRNA levels; (3) increased muscle protein content via regulating the protein kinase B/target of rapamycin signalling pathway and (4) decreased malondialdehyde and protein carbonyl contents, increased catalase, glutathione-S-transferase, glutathione reductase and GSH activities, up-regulated mRNA levels of antioxidant enzymes related to NFE2-related factor 2 and γ-glutamylcysteine ligase catalytic subunit. These results suggest that Thr has a potential role to improve muscle growth and protein synthesis, which might be due to the regulation of GH-IGF system, muscle growth-related gene, antioxidative capacity and protein synthesis-related signalling pathways. Based on the quadratic regression analysis of specific growth rate, the Thr requirement of hybrid catfish (14·19-25·77 g) was estimated to be 13·77 g/kg of the diet (33·40 g/kg of dietary protein).

Estimating the optimal threonine requirement for 25–50 kg pigs fed a mixture of soluble and insoluble dietary fibre

A study was conducted to estimate the threonine (Thr) requirement of pigs fed high-fibre diets. Average daily gain (ADG) and gain to feed (G:F) were linearly and quadratically increased (P < 0.01) ...

Threonine Requirements in Dietary Low Crude Protein for Laying Hens under High-Temperature Environmental Climate.

Simple SummaryThe threonine (Thr) requirement of laying hens in a high-temperature climate is scarcely referred in the review of literature. Therefore, our aim was to estimate the dietary Thr requirement in low CP diets in a high-temperature environmental climate. Based on our findings, the optimal dietary Thr requirements to optimize egg production, serum uric acid, and serum CuZn-SOD were 0.58%, 0.59%, and 0.56%, respectively, by regression analysis.Lohmann Brown hens (n = 420), at 28 weeks of age, were divided into five dietary treatments, and each treatment included six replicates of 14 laying hens. Dietary crude protein (14%) was presented as the control diet. Dietary L-Thr was added to the control diet for 12 weeks. Dietary Thr levels are 0.43%, 0.49%, 0.57%, 0.66%, and 0.74%, based on digestible base. From 28 to 40 weeks, hen-day egg production presented a quadratic trend to supplementing dietary Thr (R2 = 0.96, p = 0.02), and reached a maximum level at 0.58%. Serum uric acid demonstrated a quadratic trend (R2 = 0.62, p = 0.02) at 0.59%. Both serum total cholesterol and 3-hydroxy-3-methylglutaryl (HMG-CoA) reductase showed lower levels (p < 0.05) at 0.66% Thr. Serum CuZn-SOD elevated (p < 0.05) at 0.49%, 0.57%, and 0.66% Thr, as compared to the control group, and showed a quadratic trend (R2 = 0.87, p = 0.003) at 0.56%. Supplemental L-Thr decreased (p < 0.05) the expression of ileal HSP70 at 0.66% Thr. In summary, the optimal dietary Thr requirements to optimize egg production, serum uric acid, and serum CuZn-SOD were 0.58%, 0.59%, and 0.56%, respectively, by regression analysis.

Effect of supplemental threonine above requirement on growth performance of Salmonella typhimurium challenged pigs fed high-fiber diets1.

It was shown previously that high dietary fiber (DF) and immune system stimulation (ISS) with systemic Escherichia coli lipopolysaccharide independently increased the threonine (Thr) requirement to maximize growth performance and protein deposition (PD). However, no additive effects on the Thr requirement were observed when both DF and ISS were present. The objective of the present study was to investigate whether supplementing Thr to meet previously estimated requirements for high DF and systemic immune challenge would maintain performance of pigs exposed to an enteric immune challenge when fed high DF. A total of 128 pigs (22.6 ± SD = 1.6 kg initial BW) were assigned to 1 of 4 dietary treatments in a 2 × 2 factorial arrangement in a randomized complete block design (n = 8 pens/treatment and 4 pigs/pen) for 28 d. Treatments were a low-fiber (LF; 13% total DF) or high-fiber (HF; 20% total DF) diet with either a standard (STD; 0.65% SID) or supplemental (SUP; 0.78% SID) Thr level. After a 7-d adaptation, pigs were orally inoculated with 2 mL (2.3 × 109 CFU/mL) of Salmonella typhimurium (ST). Blood samples and rectal swabs were obtained and rectal temperature recorded to determine clinical responses and ST shedding. On day 7 postinoculation, 1 pig/pen was euthanized and mesenteric lymph nodes, spleen, and digesta (ileum, cecum, and colon) were sampled to assess ST colonization and translocation. Body weight and feed intake were recorded on day 0, 7, and 21 postinoculation to calculate ADG, ADFI, and G:F. Rectal temperature increased (P < 0.05) 24 h postinoculation and remained elevated at day 6. Serum albumin concentration decreased (P < 0.05), whereas haptoglobin concentration increased (P < 0.05) postinoculation. There was no fiber or Thr effect (P > 0.05) on ST counts in the ileum and cecum, but a fiber × Thr interaction (P < 0.05) was observed in the colon. Supplemental Thr improved (P < 0.05) growth performance in LF- and HF-fed challenged pigs. However, performance of supplemented HF challenged pigs was less than (P < 0.05) supplemented LF challenged pigs. These results suggest that Thr supplemented to meet requirements for high DF and systemic immune challenge was not sufficient to maintain growth performance of pigs fed HF diets and challenged with an enteric pathogen.

Effects of dietary fiber and threonine on performance, intestinal morphology and immune responses in broiler chickens.

The present experiment was conducted to investigate the effects of fiber and threonine (Thr) on growth performance, intestinal morphology and immune responses of broiler chickens. A total of 420 one-day-old mixed sex broiler chicks (Ross 308) were randomly divided into 6 experimental diets and 5 replicates of 14 chicks based on a factorial arrangement (2 × 3) from 1 to 42 d of age. Experimental factors included dietary supplemental fiber type (no supplemental fiber [NSF], 30 g/kg sugar beet pulp [SBP] or 30 g/kg rice hull [RH]) and Thr inclusion level (100% or 110% of Thr requirement recommended by breeder company [Ross 308]). Growth performance of broilers was assayed at different periods of the experiment. Intestinal morphometric features were measured at 21 d of age. Antibody titer against sheep red blood cells (SRBC), Newcastle and influenza disease viruses were measured on d 30 of trial. Dietary inclusion of SBP and RH significantly decreased feed intake and weight gain during the entire rearing period (P < 0.05). Interaction of fiber and Thr had no beneficial effects on the performance of chickens across the entire rearing phase. Dietary supplementation of 110% Thr required level improved jejunal morphometric features (P < 0.05), whereas its inclusion with fibrous materials failed to show the same effects. Dietary supplemental Thr together with SBP significantly increased antibody production against SRBC (P < 0.05). In conclusion, although supplemental 30 g/kg fibrous materials impaired growth performance, inclusion of SBP along with 110% Thr level improved the humoral immunity in broiler chickens.

Efficiency of utilizing standardized ileal digestible lysine and threonine for whole-body protein retention in pregnant gilts during early, mid-, and late gestation1.

Two experiments were conducted to determine the efficiency of utilizing SID Lys and Thr for whole-body protein retention (kSIDLys and kSIDThr) in pregnant gilts. In Exp. 1, 45 gilts (158.0 ± 8.0 kg at day 39.4 ± 1 of gestation) in 2 groups were used in a 3-period nitrogen (N)-balance study. Gilts were assigned to 1 of 4 diets set to provide 60, 70, 80, and 90% of predicted daily SID Lys requirement for protein retention (NRC, 2012) in each of early (day 41 to 52, 10.44 g/d), mid- (day 68 to 79, 9.60 g/d), and late gestation (day 96 to 107, 16.04 g/d). Diets contained 3,300 kcal ME/kg and 11.6% CP; given at a rate of 2.13 kg/d in early and mid-gestation and at 2.53 kg/d during late gestation. The 12-d balance period (7-d adaptation; 5-d urine and fecal collection) was based on total urine collection using urinary catheters and determination of fecal N digestibility using indigestible marker. The SID Lys required for whole-body protein retention was estimated using the NRC (2012) model and the predicted Lys content of each gestation pool. Lysine efficiency at each diet Lys level was calculated as the ratio of daily Lys retention and SID Lys intake. The linear and quadratic response in whole-body N and Lys retention and Lys efficiency for each balance period was determined. The kSIDLys was determined from the slope generated by regressing whole-body Lys retention vs. SID Lys intake, with y-intercept set to 0. In Exp. 2, 45 gilts (165.7 ± 13.6 kg at day 39.1 ± 2 of gestation) were assigned to 1 of 4 diets set to provide 60, 70, 80, and 90% of the predicted daily SID Thr requirement for protein retention in each of early (6.46 g/d), mid- (6.05 g/d), and late gestation (9.75 g/d). Animal management, N-balance procedure, data collection and calculation, and statistical analyses were patterned from Exp. 1. In early and mid-gestation, whole-body N retention, as well as Lys and Thr retention, was not affected by the dietary SID Lys and Thr. In late gestation, there was a linear increase (P < 0.001) in whole-body N, Lys and Thr retention. The kSIDLys and kSIDThr in late gestation were determined to be 0.54. The lack of response in whole-body protein retention in early and mid-gestation may in partly reflect excess Lys and Thr intake. Lysine and Thr efficiency calculated at the lowest dietary Lys and Thr was 0.49 and 0.32 in early gestation and 0.61 and 0.52 in mid-gestation, respectively. Based on the available evidence, kSIDLys and kSIDThr do not appear to be constant throughout gestation.

Immune system stimulation increases dietary threonine requirements for protein deposition in growing pigs.

Previous studies have reported an increase in the utilization of threonine (Thr) during immune system stimulation (ISS). However, increased utilization of an AA during ISS may not reflect an increased dietary requirement, as endogenous sources may supply AA to meet the need for enhanced utilization. The current study evaluated the impact of ISS on components of dietary Thr requirements, i.e., maintenance requirement and the efficiency of Thr utilization. Thirty-nine gilts (initial BW 32 ± 2.1 kg) of commercially relevant genetics were individually housed in metabolism crates and fed one of six experimental diets in which Thr was the first limiting among other AA. Three levels of dietary Thr were tested within each ISS group: 70%, 90%, and 110% of daily Thr requirements, which were estimated based on the potential of each ISS group for protein deposition (PD). Following adaptation to the experimental diets, pigs from each dietary treatment group were injected with either increasing amounts of Escherichia coli lipopolysaccharide (ISS+; 25 and 35 µg/kg BW) or saline (ISS-). Injections were given 48-h apart and whole-body nitrogen balance was measured for 72-h following the first injection. Body temperature (BT) was monitored and blood samples were collected 24 h after initiation of ISS and evaluated for measures of blood chemistry. Blood chemistry and BT results indicated an effective ISS in pigs (P < 0.03). Threonine intake increased PD in a linear fashion in both ISS groups (P < 0.01). The marginal efficiency of standardized ileal digestible (SID) Thr utilization for PD, represented by the slope, was not affected by ISS. However, ISS substantially increased the extrapolated maintenance SID Thr requirements, represented by the intercept at zero PD (ISS- vs. ISS+, -11.2 vs. -56.3 SE 13.2; P < 0.05). Collectively, our results indicated that the physiological changes associated with ISS increased the dietary SID Thr requirements for PD due to an increase in maintenance requirements.

Impact of dietary fiber and immune system stimulation on threonine requirement for protein deposition in growing pigs.

High dietary fiber (DF) and immune system stimulation (ISS) are thought to limit amino acid availability for protein deposition (PD) in growing pigs. A nitrogen-balance study was conducted to determine Thr requirement for optimal PD when DF and ISS were present alone and in combination. A total of 90 barrows (20.5 kg initial BW; SD = 0.75 kg) were randomly assigned to one of 10 dietary treatments (n = 9) in nine blocks. Diets consisted of a low fiber (LF; 12.5% total DF) or high fiber (HF; 18.5% total DF by adding 10% sugar beet pulp and 5% wheat bran to the LF diet) with graded levels of Thr (0.49%, 0.57%, 0.65%, 0.73%, and 0.81% standardized ileal digestible [SID]) fed at 2.2 × maintenance ME requirements. After an 8-d adaptation, two 4-d nitrogen balance collection periods (pre-ISS and ISS) were conducted. ISS was induced by repeated injections (i.m.) of increasing doses of Escherichia coli lipopolysaccharide. Blood samples were taken during both periods to assess acute phase proteins and complete blood cell count. Data were analyzed by PROC MIXED with fixed effects of period, Thr, fiber, and their interactions, with block as a random effect. Nitrogen balance was analyzed separately for each period. Threonine requirement was estimated using PROC NLIN quadratic break-point model. Serum concentration of albumin, haptoglobin, fibrinogen, whole blood white blood cell, and platelet count were affected by ISS (P < 0.001) confirming successful ISS. During pre-ISS, PD increased linearly (P < 0.01) as Thr concentration in the diet increased, with a significant interaction (P < 0.05) between fiber and Thr. During ISS, PD increased linearly (P < 0.05) as Thr concentration in the diet increased. Quadratic break-point model estimated SID Thr required to maximize PD of pigs fed LF and HF diets during pre-ISS period was 0.68% (R2 = 0.88) and 0.78% (R2 = 0.99), respectively. During ISS, the SID Thr requirement was estimated at 0.76% (R2 = 0.76) for LF diet and 0.72% (R2 = 0.95) for HF fed pigs. HF and ISS independently increased Thr requirement for maximum PD, but these effects were not additive. HF may therefore mask the effects of ISS on Thr requirement for immune response and PD.