GLUTAMIC ACID IMPROVES BODY WEIGHT GAIN AND INTESTINAL MORPHOLOGY OF BROILER CHICKENS SUBMITTED TO HEAT STRESS

Metabolomics analysis to interpret changes in physiological and metabolic responses to chronic heat stress in Pekin ducks

Heat stress (HS) is a major environmental threat that affects duck production in subtropical and tropical regions, especially in summer. This study aimed to evaluate the physiological and metabolic responses of Pekin ducks to chronic HS conditions via liquid chromatography-mass spectrometry (LC-MS) using a paired-fed (PF) experimental design. On the basis of equivalent feed intake (HS vs. PF), HS significantly reduced growth performance and the percentage of leg and breast muscles, however, markedly increased the percentage of abdominal fat and breast skin fat. Serum metabolomics results revealed that heat-stressed ducks showed enhanced glycolysis and pentose phosphate pathways, as demonstrated by higher glucose 6-phosphate and 6-phogluconic acid levels in the PF vs. HS comparison. HS decreased hepatic mRNA levels of mitochondrial fatty acid β-oxidation-related genes (MCAD and SCAD) compared to the PF group, resulting in acetylcarnitine accumulation in serum. Moreover, HS elevated the concentrations of serum amino acids and mRNA levels of ubiquitination-related genes (MuRF1 and MAFbx) in the skeletal muscle and amino acid transporter-related genes (SLC1A1 and SLC7A1) and gluconeogenesis-related genes (PCK1 and PCase) in the liver compared to the PF group. When compared to the normal control group (NC), HS further decreased growth performance, but it elevated the abdominal fat rate. However, increased mRNA levels of ubiquitination-related genes and serum amino acid accumulation were not observed in the HS group compared to the NC group, implying that reduced feed intake masked the effect of HS on skeletal muscle breakdown and is a form of protection for the organism. These results suggest that chronic HS induces protein degradation in the skeletal muscle to provide amino acids for hepatic gluconeogenesis to provide sufficient energy, as Pekin ducks under HS conditions failed to efficiently oxidise fatty acids and ketones in the mitochondria, leading to poor growth performance and slaughter characteristics.

Glutamate Supplementation Improves Growth Performance, Rumen Fermentation, and Serum Metabolites in Heat-Stressed Hu Sheep

This study evaluated the effect of glutamate supplementation on the physiological parameters of heat-stressed Hu sheep. Forty-eight male Hu sheep with an average initial body weight of 17.74 ± 0.17 kg were randomly divided into two groups: The control group (CON) was fed a basal diet and a treatment group (GLU) was fed a basal diet + 3 g/head/day of L-glutamate. There were six replications in each group with four sheep in each replication for a 90 days feeding test. Growth performance, serum biochemistry, and serum hormones were measured during phase 1 (1–30 days), phase 2 (31–60 days), and phase 3 (61–90 days) of the experiment; rumen fermentation characteristics, nutrient digestibility, and slaughter performance were measured at the end of the experimental periods. There were no differences in growth performance, serum biochemical indices, and immune indices between CON and GLU during phases 1 and 2. However, a higher average daily gain (ADG), a lower average daily feed intake (ADFI), and a lower F:G ratio (ADFI/ADG) were observed in GLU during phase 3 (p < 0.05). Serum levels of glutamate, globulin, immunoglobulin A, immunoglobulin G, immunoglobulin M, and growth hormone in GLU were higher than those in CON only on day 90 (p < 0.05). Serum levels of heat shock protein 70, adrenocorticotrophic hormone, corticosterone, triiodothyronine, and tetraiodothyronine in GLU were lower than those in CON on day 90 (p < 0.05). At the end of the experiment, ruminal pH, microbial crude protein, ammonia nitrogen, and isovalerate concentrations in GLU were higher than those in CON (p < 0.05). The apparent digestibility of dry matter, organic matter, and crude protein in GLU was higher than those in CON (p < 0.05). There were no differences in carcass traits and organ indices but spleen weight and spleen index tended to be higher in GLU. In conclusion, dietary glutamate supplementation improved rumen fermentation, increased nutrition digestibility and metabolism, enhanced immunity, and promoted growth performance of heat-stressed Hu sheep. This suggests that a longer period of glutamate supplementation (not less than 60 days) at a level of 3 g/head/day is beneficial to Hu sheep under heat stress.

Functional Amino Acids in Pigs and Chickens: Implication for Gut Health

In pigs and broiler chickens, the gastrointestinal tract or gut is subjected to many challenges which alter performance, animal health, welfare and livability. Preventive strategies are needed to mitigate the impacts of these challenges on gut health while reducing the need to use antimicrobials. In the first part of the review, we propose a common definition of gut health for pig and chickens relying on four pillars, which correspond to the main functions of the digestive tract: (i) epithelial barrier and digestion, (ii) immune fitness, (iii) microbiota balance and (iv) oxidative stress homeostasis. For each pillar, we describe the most commonly associated indicators. In the second part of the review, we present the potential of functional amino acid supplementation to preserve and improve gut health in piglets and chickens. We highlight that amino acid supplementation strategies, based on their roles as precursors of energy and functional molecules, as signaling molecules and as microbiota modulators can positively contribute to gut health by supporting or restoring its four intertwined pillars. Additional work is still needed in order to determine the effective dose of supplementation and mode of administration that ensure the full benefits of amino acids. For this purpose, synergy between amino acids, effects of amino acid-derived metabolites and differences in the metabolic fate between free and protein-bound amino acids are research topics that need to be furtherly investigated.

Protein and Amino Acid Metabolism in Poultry during and after Heat Stress: A Review

This review examined the influence of environmental heat stress, a concern facing modern broiler producers, on protein metabolism and broiler performance, as well as the physiological mechanisms that activate and control or minimize the detrimental impacts of stress. In addition, available scientific papers that focused on amino acids (AA) digestibility under stress conditions were analyzed. Furthermore, AA supplementation, a good strategy to enhance broiler thermotolerance, amelioration, or stress control, by keeping stress at optimal levels rather than its elimination, plays an important role in the success of poultry breeding. Poultry maintain homeothermy, and their response to heat stress is mainly due to elevated ambient temperature and the failure of effective heat loss, which causes a considerable negative economic impact on the poultry industry worldwide. Reduced feed intake, typically observed during heat stress, was the primary driver for meat production loss. However, accumulating evidence indicates that heat stress influences poultry metabolism and endocrine profiles independently of reduced feed intake. In conclusion, high ambient temperatures significantly reduced dietary AA intake, which in turn reduced protein deposition and growth in broilers. Further studies are required to determine the quantity of the AA needed in warm and hot climates and to introduce genetic tools for animal breeding associated with the heat stress in chickens.

Heat stress on microbiota composition, barrier integrity, and nutrient transport in gut, production performance, and its amelioration in farm animals

Livestock species experience several stresses, particularly weaning, transportation, overproduction, crowding, temperature, and diseases in their life. Heat stress (HS) is one of the most stressors, which is encountered in livestock production systems throughout the world, especially in the tropical regions and is likely to be intensified due to global rise in environmental temperature. The gut has emerged as one of the major target organs affected by HS. The alpha- and beta-diversity of gut microbiota composition are altered due to heat exposure to animals with greater colonization of pathogenic microbiota groups. HS also induces several changes in the gut including damages of microstructures of the mucosal epithelia, increased oxidative insults, reduced immunity, and increased permeability of the gut to toxins and pathogens. Vulnerability of the intestinal barrier integrity leads to invasion of pathogenic microbes and translocation of antigens to the blood circulations, which ultimately may cause systematic inflammations and immune responses. Moreover, digestion of nutrients in the guts may be impaired due to reduced enzymatic activity in the digesta, reduced surface areas for absorption and injury to the mucosal structure and altered expressions of the nutrient transport proteins and genes. The systematic hormonal changes due to HS along with alterations in immune and inflammatory responses often cause reduced feed intake and production performance in livestock and poultry. The altered microbiome likely orchestrates to the hosts for various relevant biological phenomena occurring in the body, but the exact mechanisms how functional communications occur between the microbiota and HS responses are yet to be elucidated. This review aims to discuss the effects of HS on microbiota composition, mucosal structure, oxidant-antioxidant balance mechanism, immunity, and barrier integrity in the gut, and production performance of farm animals along with the dietary ameliorations of HS. Also, this review attempts to explain the mechanisms how these biological responses are affected by HS.

Incubation variables, performance, and morphometry of the duodenal mucosa of Japanese quails (Coturnixcoturnix japonica) submitted to different incubation temperatures and thermally challenged after hatching

ABSTRACT This study aimed to evaluate the effects of different temperatures on incubation variables, performance, and morphometry of the duodenal mucosa of Japanese quails (Coturnix coturnix japonica) submitted to chronic heat stress after hatching. We distributed 540 eggs in three incubators with a temperature of 37.8°C and 60% of humidity. From the 6th day of incubation until hatching, the temperatures were adjusted to (37.8°C, 38.5°C and 39.5°C). After hatching, quails were evaluated for the quality score, weighed, and distributed in a completely randomized design with three incubation temperatures (37.8, 38.5, and 39.5°C) and two ambient temperatures (stress and thermoneutral). At 10, 20, 30, and 40 days they were weighed to determine the live weight (g) and weight gain(g). To collect the duodenum and determine morphometric parameters, we euthanized four quails of each treatment. The data were analyzed, and the differences between the means determined by the Tukey test at 5%. The incubation temperature of 39.5°C provided lower hatching rate and the live weight at birth; however, from the 10th day of age, increased live weight, weight gain, and positively influenced the morphological parameters of the duodenal mucosa in situations of chronic stress.

Broiler production challenges in the tropics: A review

Under tropical climate, broiler production is encumbered by several constraints which make it difficult for them to attain their genetic potential. The scarcity and high price of poultry feed and veterinary services and the harsh environmental conditions with respect to thermal stress are some of the challenges that hinder optimal growth of the birds. Limited availability of feedstuffs, including crucial feed ingredients like maize and oil seedcakes, is an important challenge to the sector, since feed still represents a major cost of producing broiler chickens. Additionally, the problem of climate change, which has become a global concern, is the main problem in broiler production under hot and humid climate. Under high ambient temperature, feed intake decreases, carbohydrates metabolism and protein synthesis efficiency are disturbed. Lipid utilization is lower and glucose or insulin homeostasis is altered while fat deposition and oxidative stress increases. Several strategies are used to ameliorate the effect of heat stress in poultry. The objective of this review was to summarize the challenge in broiler production under hot and humid climate and different approaches to fight heat stress in poultry.

Interorgan Metabolism, Nutritional Impacts, and Safety of Dietary L-Glutamate and L-Glutamine in Poultry

L-glutamine (Gln) is the most abundant amino acid (AA) in the plasma and skeletal muscle of poultry, and L-glutamate (Glu) is among the most abundant AAs in the whole bodies of all avian tissues. During the first-pass through the small intestine into the portal circulation, dietary Glu is extensively oxidized to CO₂, but dietary Gln undergoes limited catabolism in birds. Their extra-intestinal tissues (e.g., skeletal muscle, kidneys, and lymphoid organs) have a high capacity to degrade Gln. To maintain Glu and Gln homeostasis in the body, they are actively synthesized from branched-chain AAs (abundant AAs in both plant and animal proteins) and glucose via interorgan metabolism involving primarily the skeletal muscle, heart, adipose tissue, and brain. In addition, ammonia (produced from the general catabolism of AAs) and α-ketoglutarate (α-KG, derived primarily from glucose) serve as substrates for the synthesis of Glu and Gln in avian tissues, particularly the liver. Over the past 20 years, there has been growing interest in Glu and Gln metabolism in the chicken, which is an agriculturally important species and also a useful model for studying some aspects of human physiology and diseases. Increasing evidence shows that the adequate supply of dietary Glu and Gln is crucial for the optimum growth, anti-oxidative responses, productivity, and health of chickens, ducklings, turkeys, and laying fowl, particularly under stress conditions. Like mammals, poultry have dietary requirements for both Glu and Gln. Based on feed intake, tissue integrity, growth performance, and health status, birds can tolerate up to 12% Glu and 3.5% Gln in diets (on the dry matter basis). Glu and Gln are quantitatively major nutrients for chickens and other avian species to support their maximum growth, production, and feed efficiency, as well as their optimum health and well-being.

Effect of glutamine on the growth performance, digestive enzyme activity, absorption function, and mRNA expression of intestinal transporters in heat-stressed chickens

To explore the effect of glutamine (Gln) on the growth performance, digestive enzyme activity, absorption function and mRNA expression of intestinal transporters in heat-stressed chickens, 540 21-day-old Arbor Acres broilers were randomly assigned to a control group (no stress, NS), Gln group (Chickens were administered 0.5% and 1.0% Gln, respectively), heat stress group (HT), and Gln + HT group (Chickens were administered 0.5% and 1.0% Gln, respectively). The chickens in the HT and Gln + HT groups were reared under HT (36 ± 1 °C for 10 h/d and 22 ± 1 °C for 14 h/d), for 21 days. In contrast to the NS group, heat stress caused a reduction in the body weight gain (BWG); feed intake (FI); activity of trypsin, lipase, alkaline phosphatases, Ca²⁺ and Mg²⁺ adenosine triphosphatases, and Na⁺-K⁺-ATPase; and content of glutathione and d-xylose (P < 0.05) in the other groups. In addition, compared to the F:G and expression levels in the NS group, the heat stress increased the feed intake:body weight gain (F:G) and mRNA expression levels of SGLT1, CaBP-D28k, and L-GSBP (P < 0.05). Furthermore, HT-challenged birds were pretreated with Gln, the BWG; FI; activity of trypsin, lipase, alkaline phosphatase, Ca²⁺ and Mg²⁺ adenosine triphosphatases, and Na⁺-K⁺-ATPase; and content of glutathione and d-xylose (P < 0.05) were dramatically increased, but it decreased the F:G and mRNA expression levels of SGLT1, CaBP-D28k, and L-GSBP (P < 0.05) in the HT group. In summary, Gln can effectively improve growth performance and may promote digestion and absorption in the gastrointestinal tract by mediating the mRNA expression level of nutrient transporters and Gln metabolism in heat-stressed broilers.

Short communication: Performance, intestinal permeability, and metabolic profile of calves fed a milk replacer supplemented with glutamic acid

The objective of this study was to evaluate the potential benefits of supplementing glutamic acid in milk replacers (MR) with respect to calf performance, intestinal permeability, and metabolism. Sixty Holstein male calves (3 ± 1.3 d old and 45 ± 5.9 kg body weight) were individually housed and fed a control MR without AA supplementation (24.8% crude protein and 19.1% fat, dry matter basis), or MR supplemented with 0.3% glutamic acid (25.1% crude protein and 20.3% fat, dry matter basis). Animals followed the same MR feeding program and were weaned at 56 d of the study. The amount of starter concentrate offered was restricted to limit the effect of concentrate intake on calf metabolism. Individual daily consumption and weekly body weight were measured, and 4 h after the morning feeding, blood samples were obtained at 14 and 35 d to determine general biochemical parameters and plasma AA concentrations. On d 10 of the study, we conducted an intestinal permeability test by including 21 g of lactulose and 4.2 g of d-mannitol as markers in the MR. We found no differences in calf performance or in intestinal permeability (measured as lactulose:mannitol ratio). Serum glucose concentration was greater in unsupplemented calves than in Glu-supplemented calves. At 14 d, the proportion of plasma Leu was greater in Glu-supplemented calves; the proportion of Ile tended to be greater in Glu-supplemented calves; and the proportion of Met tended to be greater in unsupplemented calves. We observed no other differences. Small changes occurred in AA metabolism when supplementing calf MR with 0.3% glutamic acid, without leading to improvements in calf performance or changes in intestinal permeability.

Potassium phosphate and potassium carbonate administration by feed or drinking water improved broiler performance, bone strength, digestive phosphatase activity and phosphorus digestibility under induced heat stress conditions

Potassium phosphate (K₂HPO₄) and potassium carbonate (K₂CO₃) administration by feed or water were evaluated on broiler performance, bone strength, alkaline phosphatase activity (ALP), and phosphorus digestibility under heat stress and high chloride condition. Experimental groups include control; 15 cc/kg K₂HPO₄; 30 cc/kg K₂HPO₄; 15 cc/l K₂HPO₄; and 3.7 g/kg K₂CO₃. Body weight (BW), feed and water consumption, plasma potassium, phosphorus, and calcium concentration along with plasma and digestive ALP and intestinal digesta pH were measured during the trial. Tibia ash, calcium and phosphorus content, and breaking strength were measured on days 21 and 42 and phosphorus digestibility on day 36 of age. As a result of this, study feed and water consumption was increased by supplementation of the feed or water with K₂HPO₄ (P ≤ 0.001). K₂HPO₄ increased body weight at 42 days of age (P ≤ 0.001). Tibia ash and phosphorus content was increased by K₂HPO₄ supplementation (P ≤ 0.004; P ≤ 0.003). K₂CO₃ did increased tibia ash but not changed tibia phosphorus content significantly. Tibia shear force, shear energy, extension, and length were improved by K₂HPO₄ administration at 42 days of age (P ≤ 0.001). Administration of either feed or water with K₂HPO₄ increased plasma potassium, phosphorus, and calcium concentration at 21 days of age, whereas K₂CO₃ reduced plasma potassium at 21 days of age (P ≤ 0.05). Plasma ALP reduced by addition of 15 cc K₂HPO₄ and K₂CO₃ to diets at 42 days of age, whereas digestive ALP was increased by inclusion of K₂HPO₄ and not by K₂CO₃. Supplementation of either feed or water with K₂HPO₄ increased phosphorus digestibility, whereas K₂CO₃ reduced phosphorus digestibility (P ≤ 0.003). Jejunum and ileum pH was reduced by K₂HPO₄ or by K₂CO₃ at 21 and 42 days of age (P ≤ 0.006; (P ≤ 0.05). Over all, results of current study revealed that K₂HPO₄ can be a suitable potassium salt choice instead of KCL in hot weather conditions especially when the water or diet contains high levels of chloride.

Glutamine alleviates heat stress-induced impairment of intestinal morphology, intestinal inflammatory response, and barrier integrity in broilers

The aim of this study was to investigate the protective effect of glutamine (Gln) on the intestinal morphology, intestinal inflammatory response, and barrier integrity in broilers exposed to high ambient temperature. Three-hundred-sixty 21-d-old Arbor Acres broilers (half male and half female) were randomly allocated to 4 treatment groups in a completely randomized design, each of which included 6 replicates with 15 birds per replicate, for 21 d. The 4 treatment groups were as follows: the control group, in which birds were kept in a thermoneutral room at 22 ± 1°C (no stress, NS; fed a basal diet); the heat stress group (36 ± 1°C for 10 h/d from 08:00 to 18:00 h and 22 ± 1°C for the remaining time, heat stress (HT); fed a basal diet); and heat stress + Gln group (0.5 and 1.0% Gln, respectively). Compared to the NS group, broilers in the HT group had lower villus height (P < 0.05), higher crypt depth (P < 0.05), higher D-lactic acid and diamine oxidase (DAO) activity (P < 0.05), higher soluble intercellular adhesion molecule-1 (sICAM-1) concentration (P < 0.05), higher tumor necrosis factor (TNF)-α/interleukin (IL)-10 (P < 0.05), and lower tight junction protein expression levels (P < 0.05). Compared with birds in the HT, birds in the HT + Gln group exhibited increased villus height (P < 0.05), decreased D-lactate and DAO activity (P < 0.05), decreased sICAM-1 concentration (P < 0.05), and mediate the secretion of cytokines (P < 0.05), as well as increased zonula occludens-1 (ZO-1), claudin-1, and occludin mRNA expression levels (P < 0.05). In conclusion, these results indicate that supplementation with Gln was effective in partially ameliorating the adverse effects of heat stress on intestinal barrier function in broilers by promoting epithelial cell proliferation and renewal, modifying the function of the intestinal mucosa barrier, and regulating the secretion of cytokines.

Morphometry of pectoral muscle fiber and intestinal villi of Calidris pusilla during the wintering period in Brazil

ABSTRACT: Migration is an event observed in several animals, such as shorebirds moving between the northern and southern hemispheres, during breeding and wintering intervals. Morphophysiological adaptations are necessary to allow the maintenance of migratory cycles and, therefore, studies with this focus can help clarify biological aspects related to migration. We analyzed the morphology variation in pectoral muscles and intestinal mucosa of Calidris pusilla, during different phases of the wintering period on the coast of Brazil. Fragments of pectoral muscles and duodenal were collected, fixed and processed for histology according to standard procedure, from specimens captured in a locality on the Brazilian coast. Modifications were found in the measured parameters among the three phases of wintering, arrival in Brazil (October, mid-period), January and departure to the Northern Hemisphere - May. The registered structural dynamism characterizes the growth of flight musculature and intestinal changes related to nutrition. Such changes occur temporarily due to the activities of preparation and migration between the northern and southern hemispheres.