Topic:Amino Acids
Amino acids are organic compounds that serve as the building blocks of proteins and play crucial roles in various physiological processes in horses. They are essential for growth, tissue repair, and the synthesis of enzymes and hormones. Amino acids are categorized into essential amino acids, which must be obtained through the diet, and non-essential amino acids, which can be synthesized by the horse's body. Key essential amino acids for equine health include lysine, methionine, and threonine, which are vital for muscle development, immune function, and overall well-being. Amino acid levels can influence performance, recovery, and metabolic efficiency in horses, making their study important for optimizing equine nutrition and health management. This page compiles peer-reviewed research studies and scholarly articles that explore the role, metabolism, and clinical importance of amino acids in equine physiology and their impact on performance and health outcomes.
Nutritional and Non-nutritional Aspects of Forage. Many forage types are available, typically divided into cool or warm season grasses and legumes, which can be fed as fresh pasture or after preservation. Testing for nutrient content confirms what should be supplemented to make up shortfalls. Although testing is recommended, it is not always practical. Typical values for the forage type are available; however, they cannot be relied on for actual content. Non-nutritional aspects must also be taken into account. The provision of complementary feeds to ensure adequate vitamin and mineral intake is recommended. Additional supplementary high-qualit...
Effect of Hay Soaking Duration on Metabolizable Energy, Total and Prececal Digestible Crude Protein and Amino Acids, Non-Starch Carbohydrates, Macronutrients and Trace Elements. Soaking hay before feeding has been documented to reduce airborn respirable particles and water-soluble carbohydrate (WSC) content which may have positive benefits for horses suffering from Equine Asthma (EA) or Equine Metabolic Syndrome (EMS). Prolonged soaking also leaches minerals, but to-date no measurement of the loss of small intestine digestible crude protein has been documented. One aim of this study was to investigate various soaking durations on nutrient contents of hay, WSC, macronutrients, and trace elements levels. Another objective was to determine the prececal digestible crude p...
The effect of time of feeding on plasma amino acids during exercise and recovery in horses. Feeding management in horses suggests feeding horses in advance of exercise, particularly the grain portion of the diet. Plasma amino acids () peak at 3 to 6 h postfeeding depending on the AA. The timeframe between feeding and exercise may affect the availability of AA during and after exercise. The purpose of this study was to observe the differences in plasma AA in horses fed prior to exercise or after exercise. Eight light type horses were fed a diet with adequate protein and AA for horses in light to moderate exercise. After an adjustment period, horses completed a standardized exercise te...
Plasma amino acid concentrations during experimental hyperinsulinemia in 2 laminitis models. Endocrinopathic laminitis develops in association with insulin dysregulation, but the role of insulin in the pathogenesis remains unclear. Hyperinsulinemia can cause hypoaminoacidemia, which is associated with integumentary lesions in other species and therefore warrants investigation as a potential mechanism in laminitis. Objective: Evaluate plasma amino acid concentrations in the euglycemic-hyperinsulinemic clamp (EHC) and prolonged glucose infusion (PGI) laminitis models. Methods: Sixteen Standardbred horses. Methods: Prospective experimental study. Plasma amino acid concentrations were mea...
Peripheral Modulators of the Central Fatigue Development and Their Relationship with Athletic Performance in Jumper Horses. The current study aimed to investigate whether peripheral modulators of serotoninergic function and neurohumoral factors' changes in athletic horses during an official jumping competition, and to evaluate their relationship with the physical performance of competing horses. From 7 Italian Saddle mares (6-9 years; mean body weight 440 ± 15 kg), performing the same standardized warm-up and jumping course during an official class, heart rate (HR) was monitored throughout the competition. Rectal temperature (RT) measurement, blood lactate and glucose concentration, serum tryptophan, leucine, vali...
Exploring Potential Bioactive Peptides in Fermented Bactrian Camel’s Milk and Mare’s Milk Made by Mongolian Nomads. To date, bioactive proteins and peptides from minor livestock milks and their fermented products have been scarcely reported. In Mongolia, nomads are commonly rearing five livestock animal species (i.e., cow, camel, goat, horse, and sheep) for milking and other purposes. In this study, we analyzed the peptide composition in fermented milks of Bactrian camels () and horses, produced by Mongolian nomads for self-consumption. Peptides from skimmed fermented milks were separated by ultrafiltration and reverse-phase high-performance liquid chromatography. Then, their amino acid sequences were deter...
Dynamic Change of Free Serum L-carnitine Concentration in Relation to Age, Sex, and Exercise in Anglo-Arabian Thoroughbred Horses. The physiological role of L-carnitine in equine species is worthy of investigation; however, the systemic content of free L-carnitine and its dynamic change in growing foals as well as in exercising horses are still poorly investigated. In this study, the influence of age and exercise on free serum L-carnitine levels was evaluated in equine species. Ten foals were monitored from 6 up to 18 months of age (group 1), whereas 60 horses were divided in six groups in accordance with their age: group 2, 2-year-old; group 3, 3-year-old; group 4, 4-year-old; group 5, 5-year-old; group 6, 6-year-old; g...
Relative Deficiency in Albumin Methionine Content is Associated With Decreased Antioxidant Capacity of Equine Plasma. Relative to other species, horses seem particularly susceptible to oxidative stress. Plasma albumin plays an important role in preventing oxidative damage, in part due to its methionine (MET) content. Equine albumin is highly unusual in that it contains no MET residues. Whether or not this causes deficient antioxidant capacity in equine plasma relative to that of other species has not yet been explored. The objective of this study was to compare the redox status of equine (no MET) to that of bovine (moderate amount of MET) plasma. Plasma was collected from healthy, nonpregnant Quarter Horse ma...
Pathways regulating equine skeletal muscle protein synthesis respond in a dose-dependent manner to graded levels of protein intake. Activation of the mechanistic target of rapamycin (mTOR)-controlled anabolic signaling pathways in skeletal muscle of rodents and humans is responsive to the level of dietary protein supply, with maximal activation and rates of protein synthesis achieved with 0.2 to 0.4 g protein/kg body weight (BW). In horses, few data are available on the required level of dietary protein to maximize protein synthesis for maintenance and growth of skeletal muscle. To evaluate the effect of dietary protein level on muscle mTOR pathway activation, five mares received different amounts of a protein supplement t...
Exercise Induced Changes in Salivary and Serum Metabolome in Trained Standardbred, Assessed by 1H-NMR. In the present study, data related to the metabolomics of saliva and serum in trained standardbred horses are provided for the first time. Metabolomic analysis allows to analyze all the metabolites within selected biofluids, providing a better understanding of biochemistry modifications related to exercise. On the basis of the current advances observed in metabolomic research on human athletes, we aimed to investigate the metabolites' profile of serum and saliva samples collected from healthy standardbred horses and the relationship with physical exercise. Twelve trained standardbred horses we...
Genetics of Equine Muscle Disease. There are 5 single-gene mutations that are known to cause muscle disease in horses. These mutations alter the amino acid sequence of proteins involved in cell membrane electrical conduction, muscle energy metabolism, muscle contraction, and immunogenicity. The clinical signs depend on the pathway affected. The likelihood that an animal with a mutation will exhibit clinical signs depends on the mode of inheritance, environmental influences, and interactions with other genes. Selection of a genetic test for use in diagnostic or breeding decisions requires a knowledge of clinical signs, mode of i...
Characterizing the Serum Proteome of Donkeys (Equus asinus). Serum and plasma are commonly used in clinical practice considering the widely accepted fact that the "normal" protein expression pattern of a healthy animal changes under disease conditions. We herein used a label-free mass spectrometry-based quantitative proteomics approach to characterize the serum proteome of donkeys. A total of 277 unique proteins were identified from 2,388 unique peptides. Gene ontology analyses showed that the most frequent processes were related to metabolic activities and biological regulation, response to stimulus, and immune system processes. The main annotated area...
Evidence that human and equine erythrocytes could have significant roles in the transport and delivery of amino acids to organs and tissues. Erythrocytes have a well-defined role in the gaseous exchange of oxygen and carbon dioxide in the mammalian body. The erythrocytes can contain more than half of the free amino acids present in whole blood. Based on measures showing that venous erythrocyte levels of amino acids are much less than arterial erythrocyte levels, it has previously been proposed that erythrocytes also play a role in the delivery of amino acids to tissues in the body. This role has been dismissed because it has been assumed that to act as an amino acid transport vehicle, the erythrocytes should release their entire a...
Iron Biomineral Growth from the Initial Nucleation Seed in L-Ferritin. X-ray structures of homopolymeric human L-ferritin and horse spleen ferritin were solved by freezing protein crystals at different time intervals after exposure to a ferric salt and revealed the growth of an octa-nuclear iron cluster on the inner surface of the protein cage with a key role played by some glutamate residues. An atomic resolution view of how the cluster formation develops starting from a (μ -oxo)tris[(μ -glutamato-κO:κO')](glutamato-κO)(diaquo)triiron(III) seed is provided. The results support the idea that iron biomineralization in ferritin is a process initiating at the l...
Amino acid requirements in horses. Evaluating amino acid requirements, specifically threonine requirements, in horses will enable better feed formulation and result in economic production, improved animal health, and reduced environmental pollution. However, the current knowledge of protein and amino acid requirements in horses is still limited. Because horses have a unique digestive system and consume a variety of feed ingredients, their protein digestibility may be affected than other species by different feed composition, and thus amino acid requirements are susceptible to vary between situations. Therefore, a careful evalua...
Metabolomic Response of Equine Skeletal Muscle to Acute Fatiguing Exercise and Training. The athletic horse, despite being over 50% muscle mass, remains understudied with regard to the effects of exercise and training on skeletal muscle metabolism. To begin to address this knowledge gap, we employed an untargeted metabolomics approach to characterize the exercise-induced and fitness-related changes in the skeletal muscle of eight unconditioned Standardbred horses (four male, four female) before and after a 12-week training period. Before training, unconditioned horses showed a high degree of individual variation in the skeletal muscle metabolome, resulting in very few differences ...
Modelling of amino acid turnover in the horse during training and racing: A basis for developing a novel supplementation strategy. Horses in heavy training in preparation for racing and competition have increased metabolic demands to support the more intensive levels of exercise and recovery. However, little is known at the metabolic level about amino acid turnover and the specific alterations of demand caused by high intensity exercise. During exercise, certain amino acids are required in greater quantities due to disproportionate losses via excretory systems and usage in biosynthetic pathways. This investigation has built a theoretical computer model in an attempt to bring together the published rates of protein intake ...
Microbial diversity within the digestive tract contents of Dezhou donkeys. Gastrointestinal microbiota has significant impact on the nutrition and health of monogastric herbivores animals including donkey. However, so far the microbiota in different gastrointestinal compartments of healthy donkey has not been described. Therefore, we investigated the abundance and function of microbiota at different sites of the gastrointestinal tract (GIT) (foregut: stomach, duodenum, jejunum and ileum; hindgut: cecum, ventral colon, dorsal colon, and rectum) of healthy adult donkeys mainly based on 16S rRNA gene sequencing and phylogenetic investigation of communities by reconstruc...
A high protein meal affects plasma insulin concentrations and amino acid metabolism in horses with equine metabolic syndrome. Equine metabolic syndrome (EMS) is characterized by an abnormal insulin response to a glycemic challenge but despite the known insulinotropic effects of certain amino acids, there is a paucity of data evaluating the impact of dietary protein on insulin dynamics in these horses. The objective was therefore to assess insulin and amino acid responses following intake of a high protein meal in healthy horses and those with EMS. Six mature horses diagnosed with EMS and six age-matched control horses without EMS were used. Horses were fed 2g/kg body mass (BM) of a high protein pellet (31% crude prot...
A single amino acid change in hemagglutinin reduces the cross-reactivity of antiserum against an equine influenza vaccine strain. Equine influenza virus is an important pathogen for the horse industry because of its economic impact, and vaccination is a key control measure. Our previous work suggested that a mutation at position 144 in the hemagglutinin of Florida sublineage clade 2 viruses reduces the cross-neutralizing activity of antiserum against a former vaccine strain. To confirm this suggestion, here, we generated viruses by reverse genetics. Antibody titers against the mutated viruses were one-tenth to one-sixteenth of those against the former vaccine strain. Our findings confirm that this single amino acid subst...
Effects of dietary arginine supplementation in pregnant mares on maternal metabolism, placental structure and function and foal growth. Foals born to primiparous mares are lighter and less mature than those born to multiparous dams. Factors driving this difference are not totally understood. Using 7 multiparous and 6 primiparous standardbred mares, we demonstrated that, in late gestation, primiparous mares were less insulin resistant compared to multiparous mares, and that their foals had reduced plasma amino-acid concentrations at birth compared to foals born to multiparous mares. Vascular development, as observed through structure and gene expression, and global DNA methylation were also reduced in primiparous placentas. Ano...
Dynamic Change of Serum Levels of Some Branched-Chain Amino Acids and Tryptophan in Athletic Horses After Different Physical Exercises. Physical exercise induces several adaptations involving modulation of the energetic pathways to meet the energy demand during physical exercise. The branched-chain amino acids, leucine in particular, are considered as the most relevant amino acids, especially for exercise physiology. In this study, the change of leucine, valine, and tryptophan concentration was investigated in athletic horses before and after different exercise type. A total of 40 sport horses were equally divided into 4 groups according to the exercise type: group A (jumping), group B (reining), group C (32 km ride), and grou...
Early luteal phase progestin concentration influences endometrial function in pregnant mares. In the horse, it is still unclear if and to what extent low progestin concentration contributes to early conceptus loss. In the present study, we have investigated if reduced or elevated progestin concentration in the early luteal phase influences endometrial function and conceptus development. We hypothesized that reduced progestin concentration via delayed downregulation of endometrial progesterone receptors (PR) influences endometrial function in healthy fertile mares while progestin substitution does not. Genitally healthy estrous mares (n = 8; age 4-14 years) were inseminated and trea...
Role of homocysteine metabolism in animal reproduction: A review. Homocysteine (Hcy) is a thiol-containing essential amino acid, important for the growth of cells and tissues. Several hypotheses exist regarding Hcy toxicity in humans; Hcy is involved in protein structural modifications, oxidative stress, and neurotoxicity induction and is therefore associated with several pathological conditions in humans. In veterinary science, knowledge regarding Hcy has increased recently due to several studies; however, many aspects remain undiscovered. Many details remain unknown regarding the effect of Hcy levels on pregnancy and the optimal management of pathological ...
Plasma Amino Acid Concentrations of Horses Grazing Alfalfa, Cool-Season Perennial Grasses, and Teff. The impact of forage species on plasma amino acid (AA) concentrations of grazing horses (Equus caballus L.) is unknown. The objectives of this study were to determine the impact of different forage species on plasma AA concentrations and protein synthesis. Research was conducted in July in St. Paul, MN, USA. Alfalfa (Medicago sativa L.), mixed perennial cool-season grasses (CSGs), and teff (Eragrostis tef [Zucc.] Trotter) pastures were grazed by six horses randomly assigned to one of three forage types in a replicated Latin-square design. Horses had access to pasture each day. Jugular venous b...
Effects of dietary amino acid supplementation on measures of whole-body and muscle protein metabolism in aged horses. The objective of this study was to examine markers of whole-body and muscle protein metabolism in aged horses fed a diet typical for North American aged horses, supplemented with amino acids. In a replicated Latin square design, six aged horses (20 ± 1.1 years) were studied while receiving each of three isocaloric, isonitrogenous diets, a control treatment concentrate (CON; 100 mg/kg BW day lysine, 84 mg kg day threonine, 51 mg kg day methionine), LYS/THR (134 mg kg BW day lysine, 110 mg kg BW day threonine, 52 mg kg BW day methionine) and LYS/THR/MET (132 mg kg BW da...
The first report of polymorphisms and genetic characteristics of the prion protein gene (PRNP) in horses. Prion diseases have a wide host range, but prion-infected cases have never been reported in horses. Genetic polymorphisms that can directly impact the structural stability of horse prion protein have not been investigated thus far. In addition, we noticed that previous studies focusing on horse-specific amino acids and secondary structure predictions of prion protein were performed for limited parts of the protein. In this study, we found genetic polymorphisms in the horse prion protein gene (PRNP) in 201 Thoroughbred horses. The identified polymorphism was assessed to determine whether this p...
Freezing point and other technological properties of milk of the Polish Coldblood horse breed. Mare milk is a valued and sought-after raw material for the production of innovative dairy products. The high demand, low supply, high price, and lack of accurate characterization of the milk of a given horse breed may provoke its deliberate fraudulent dilution. The aim of this work was to analyze the freezing point against a background of various selected technological parameters of Polish Coldblood mare milk. Research was carried out on multiparous Polish Coldblood mares from 5 to 8 yr of age with live weights between 618 and 851 kg. Their milk was tested on d 1, 3, and 7 postpartum and once...
Amino acid transporter expression in the endometrium and conceptus membranes during early equine pregnancy. Maternally derived amino acids (AA) are essential for early conceptus development, and specific transporters enhance histotrophic AA content during early ruminant pregnancy. In the present study we investigated AA transporter expression in early equine conceptuses and endometrium, during normal pregnancy and after induction of embryo-uterus asynchrony. 'Normal' conceptuses and endometrium were recovered on Days 7, 14, 21 and 28 after ovulation. To investigate asynchrony, Day 8 embryos were transferred to recipient mares on Day 8 or Day 3, and conceptuses were recovered 6 or 11 days later. Endo...
Using the indicator amino acid oxidation technique to study threonine requirements in horses receiving a predominantly forage diet. Threonine has been reported to be the second limiting amino acid in typical equine diets, but its actual requirement has not been determined in horses. To evaluate amino acid metabolism and requirements, the indicator amino acid oxidation (IAAO) method has been successfully used in other species. The objective of this research was to estimate threonine requirements in mature horses fed timothy hay and concentrate in 4:1 ratio using the IAAO method. Six Thoroughbred mares (579.9 ± 46.7 kg) received each of 6 levels of threonine intake, 41, 51, 61, 70, 80 and 89 mg/kg BW/day, in a randomly ...