Influence of Glutamine and Glutamate Supplementation in the Blood Levels of Horses

Background: The most abundant free amino acid in mammals is glutamine (GLN). Little research has focused on GLN supplementation for horses, but GLN levels in this species are known to decline after exercise and during lactation. Under physiological conditions, the body produces Gln in sufficient quantities for general metabolism, and a small part of this amino acid comes from dietary protein. Little research has so far focused on equine dietary supplementation with free glutamine or combined with other amino acids during catabolic states or in highly stressful situations. This research was conducted to evaluate the effects of equine dietary supplementation using a combination of glutamine and glutamate.  Materials, Methods & Results: The study involved four Arabian mares, not in training (~380 kg; ~12 years old) and four treatments (control, and inclusions of 1, 2 and 4% of GLN+GLU) in a Latin square model. A 7-day washout period was established between each phase. Fifty percent of the mares’ maintenance energy requirements came from concentrate and 50% from hay and grazing. The other 50% came from Tifton hay (Cynodon dactylon), which was supplied ad libitum. After 7 weeks of nutritional supplementation (once a day, in the morning). In the experimental model, the mares were distributed in a Latin square design comprised of four treatments: control (without inclusion) and inclusions of 1%, 2% and 4% of supplement (AminoGut®, Ajinomoto do Brazil), and four animals. Blood was collected in five stages (fasting, and 60, 120, 240 and 360 min after feeding) in each treatment. The blood samples were analyzed to determine GLN, GLU, urea, creatinine, uric acid, total plasma protein, hematocrit and glucose levels. Glutamine and Glutamate concentrations were analyzed using the enzymatic spectrophotometric method. The results were analyzed statistically using one- and two-way ANOVA and Tukey’s test with P set at 5%. The results indicated that GLN differed in both the group (P 0.05). Significant changes in GLN levels were also observed in the 4% inclusion treatment compared to all the treatments in the fasting phase and in the + 60 min and +240 min phases of the control group (P 0.05) during the period under analysis, and remained within the normal range for the species in their current stabling conditions. The mares presented no clinical problems nor did they change their feeding behavior during the supplementation period or on the days blood was collected.Discussion: Glutamine metabolism in horses has yet to be extensively studied.  However, it has been shown that, when supplied to horses in its free form, this amino acid causes Gln levels to rise rapidly within the first 90 min of the postprandial period.  This indicates that an extra amount of this amino acid may increase Gln blood levels despite intense degradation of enterocytes. This study found that supplementation with a combination of Gln+Glu can increase blood Gln levels after 6 h in the treatment involving 4% Gln+Glu included in the concentrate (P < 0.05) In conclusion, supplementation with GLN+GLU raised the mares’ GLN levels after 360 min when 4% of GLN+GLU was included in their diet. These results may be used to establish GLN supplementation models for horses.

Glutamine and Glutamate Supplementation Increases the Levels of These Amino Acids in the Milk of Pasture-fed Mares

Background: L-Glutamine (Gln), the most abundant free alpha amino acid in the body, plays a major role in the transport of nitrogen and carbon between tissues, and is an important source of respiratory energy for intestinal and immune system cells. Mares lose lean body mass during lactation, when plasma and milk Gln levels change significantly. However, supplementation with Gln combined with other amino acids may not alter equine plasma Gln levels. The work reported here was designed to test the hypothesis that supplementation with a mixture of glutamine and glutamate (AminoGut) alters blood and milk free glutamine and glutamate levels in pasture-fed lactating mares.Materials, Methods & Results: This study involved 31 multiparous Quarter Horse mares, which were divided into three groups immediately postpartum, as follows: G-CON (n = 19); G-50 g supplemented with 50 g of Gln + Glu plus 200 g of concentrate (n = 6); and G-100 g, supplemented with 100 g of Gln + Glu plus 200 g of concentrate (n = 6). Blood and milk samples were collected on the day of parturition prior to supplementation, and monthly until weaning. The milk samples were used to analyze the Gln, Glu composition and levels, while the blood samples were used for further analysis of blood biomarkers. The results were analyzed by ANOVA and by Tukey’s test and the P value was set at 5%. The G-CON group showed a significant reduction of 11-35% in the mean blood glutamine levels from the first month postpartum and throughout lactation. In contrast, blood glutamine levels in groups G-50 g and G-100 g did not change significantly from parturition through 5 months of lactation. The supplemented groups showed no significant differences in blood variables such as protein, albumin, urea, creatinine, cholesterol, triglycerides and minerals. Free glutamine levels in milk did not change from parturition through the end of lactation in the G-CON group, but groups G-50 g and the G-100 g showed a marked rise in milk glutamine levels throughout the first three months of lactation (~3x), which remained high (~2x) until the foals were weaned (P > 0.05).Discussion: The results of this study indicate that Gln + Glu supplementation successfully increased Gln levels in mare milk in the first three months of lactation, and Glu levels in G-100 g in the first four months, without affecting the levels of these amino acids in the animals’ blood, which remained similar to data obtained at parturition. In fact, the Gln levels in both supplemented groups exceeded 1,000 mmol/mL throughout lactation, unlike those of the control group and of the samples obtained at parturition. Moreover, supplementation did not produce significant changes in blood biomarkers, including those pertaining to protein metabolism (urea, creatinine, uric acid, albumin and total proteins), indicating that the product used for supplementation did not interfere in these biomarkers, which remained within the normal physiological variations for the species. It was concluded that daily dietary supplementation with 50 g of a mixture of glutamine and glutamate produced an effect similar to supplementation with 100 g/day. Both supplementation protocols succeeded in raising glutamine levels in mare milk in the first three months of lactation, without interfering in blood biomarkers or milk composition. In view of the cost of the product, we recommend that the daily diet of mares during lactation be supplemented with 50 g of a mixture of Gln + Glu in order to produce the desired nutritional effects

Effects of L-Arginine Supplementation on Lactating Mares and the Development of Foals

Background: Most animal species are able to produce Arginine (Arg) under normal conditions. However, in some situations, its degradation can be higher than its production. For example, during a period of lactation or disease, there is an increase in the consumption of Arg. In this case, endogenous production is not enough for the animal’s demands. Indeed, Arg supplementation in animals has several benefits for the animal’s body, such as the increase of angiogenesis, improvements in immunity and the reproductive system, as well as the stimulation of lactogenesis. During the early phase of growth, a deficiency of Arg could cause a reduction in the growth rate and metabolic activity of animals. Therefore, this amino acid is considered essential in some phases of the life of animals. However, very few studies of the supplementation of this amino acid in horses have been carried out. The aim of the present study was to characterize the effects of supplementing lactating mares and their foals with Arg.Materials, Methods &amp; Results: Lactating mares (n = 10) were divided into two groups (control group: n = 3 / supplemented group: n = 7) and maintained exclusively under grazing. The supplemented group received 50 g of Arg during the lactation period. Samples of milk and blood from mares and blood from foals were collected at different phases of the lactation period. The following parameters were measured in milk: Glutamine (Gln); Glutamate (Glu); protein; fat; casein; lactose; urea and total solids. The following parameters were measured in blood: Gln; Glu; total plasmatic protein (TPP); albumin; urea; creatinine; uric acid; triglycerides; total cholesterol; calcium (C); phosphorous (P); magnesium (Mg) and ferrous (Fe). In addition, the biometric parameters of Wither Height (WH), Chest Perimeter (CP), Cannon Bone Circumference (CBC) and Fat Percentage (FP) of foals were obtained. A significant increase of Gln was observed in the milk in both groups (P &lt; 0.05). The highest concentration of Gln was detected in the third month of the lactation period in the supplemented group (~ 2.26 mmol/mL), and the control group (~ 1.91 mmol/mL) during the same period. Gln did not alter in the blood (P &gt; 0.05), although Glu was higher in the control group in the first month of the lactation period (~ 0.21 mmol/mL) (P &lt; 0.05). An increase in uric acid (~ 0.19 mmol/L) in both groups on the day of birth (P &lt; 0.05). In the supplemented group, increases in triglycerides (~ 0.60 mmol/L), Ca (~ 2.90 mmol/L) and Mg (~ 0.52 mmol/L) were observed in the first month of the lactation (P &lt; 0.05). At birth, foals exhibited high levels of urea (~ 4.67 mmol/L) and uric acid (~ 0.21 mmol/L), and low levels of P (~ 2.02 mmol/L) (P &lt; 0.05). The levels of Gln in the blood of foals remained between 0.50 and 0.70 mmol/mL throughout the lactation period (P &gt; 0.05). Even when they were added (Gln + Glu), no differences were observed (P &gt; 0.05). However, when the biometric parameters were analyzed, significant variations were detected in almost all characteristics (weight, WH, CP and CBC). In particular, the control group exhibited higher body mass and CP in the fifth month, when compared with the group of foals born from supplemented mares (P &lt; 0.05). The FP did not alter in either of the groups analyzed (P &gt; 0.05).Discussion: The results indicate that the supplementation of lactating mares with Arg produced few alterations in the parameters analyzed for both mares and foals. In addition, the supplementation did not produce side effects among the supplemented animals

Evaluation of Mangalarga Marchador foal development in the first year of life

The purpose of this study was to examine the development pattern of Mangalarga-Marchador foals by determination of muscle development and deposition of adipose tissue associated with the evaluation of blood-based biomarkers. Thus, 72 Mangalarga Marchador foals (ages ranged from 1-12 mo) were randomly selected and divided into 12 age groups (n=6 per group), evaluated monthly. The thickness of the Longissimus dorsi (LD) and rump fat (RF) were determined through an ultrasound performed on each foal’s left side. Such parameters were used to calculate the percentage of body fat (BF), fat mass (FM), and fat-free mass (FFM). Morphometric measurements were taken on the foal’s right side using a tape measure and a hypsometer. Blood samples were collected for determinations of total proteins, albumin, triglycerides, cholesterol, urea, creatinine, and glucose. Morphometric measurements,  the thickness of the LD and RF, weight, BF, FM, and FFM showed differences between age groups (P&lt;0.001). Muscle development and fat deposition in subcutaneous tissue were greater between six and 12 months and average weight gain and FFM were proportionally greater between one and six months. We concluded that morphometric measurements increase steadily and linearly during the first 12 months of life, indicating that it is feasible to use the linear regression formula. Moreover, significant differences between age and biochemical biomarkers may be attributed to nutritional and digestive physiology adaptations during these periods.O objetivo desse estudo foi examinar o padrão de desenvolvimento de potros Mangalarga Marchador através da determinação do desenvolvimento muscular e da deposição de tecido adiposo associado com avaliação de biomarcadores sanguíneos. Assim, 72 potros Mangalarga Marchador (idades entre 1 e 12 meses) foram selecionados ao acaso e divididos em 12 grupos etários (n=6/grupo), avaliados mensalmente. A espessura do Longissimus dorsi (LD) e da cobertura de gordura da garupa (RF) foi determinada através de ultrassonografia realizada do lado esquerdo de cada animal, tais parâmetros foram usados para calcular percentagem de gordura corporal (BF), massa de gordura (FM) e massa livre de gordura (FFM). Mensurações morfométricas foram obtidas do lado direito de cada potro, usando fita métrica e hipômetro. Amostras sanguíneas foram obtidas para determinações de proteínas totais, albumina, triglicérides, colesterol, uréia, creatinina e glicose. Medidas morfométricas, espessura de LD e RF, peso corporal, BF, FM e FFM mostraram diferenças entre os grupos etários (P&lt;0,001). O desenvolvimento muscular e a deposição de gordura no tecido subcutâneo foram maiores entre 6 e 12 meses e a média de ganho de peso e de FFM foi proporcionalmente maior entre entre 1 e 6 meses . Foi possível concluir que as medidas morfométricas aumentam de forma constante e linear nos primeiros 12 meses de vida, indicando que é factível usar fórmulas de regressão linear. Ainda, diferenças significativas entre idade e biomarcadores bioquímicos podem ser atribuídos às adaptações nutricionais e digestivas durante esses períodos.

Metabolic and physiological changes during and after vaquejada exercise in horses

Physiological and metabolic evaluations of equine sports have been conducted to define parameters or biomarkers for performance evaluation, clinical diagnosis and predict fatigue and overtraining. Actually, the vaquejada is the most important equine sport in Brazil, and these horses are repeatedly submitted to shortduration physical exertion, during 2 or 3 alternate or consecutive days, requiring adequate conditioning for this equestrian modality. The objective of this study was to test the hypothesis that pulls horses and helper horses undergo physiological and metabolic changes during vaquejada races. Eighteen Quarter Horses were used, including 12 pull horses and 6 helper horses. Hemograms and the following analyses were performed: glucose, lactate, cholesterol, triglycerides, NEFA, total proteins, albumin, creatine kinase, gama glutamyl transferase and cortisol. A heart rate monitor was used to measure the heart rate, velocity and travel distance of each animal. Statistical analyses were performed using ANOVA and Tukey's tests, with P established at 5%. Pull horses had higher heart rate values, but the velocities attained by the two groups of horses were similar. There was an increase in heart rate, glucose, lactate, non-esterified fatty acids and cortisol in both pull and helper horses after racing, but these levels returned to resting values 30 minutes after the end of exercise. It was concluded that the vaquejada field test promoted significant changes in haematological, biochemical biomarkers and in the heart rate of both groups of horses

Characterization of the Development of Foals in Natural Mating and Embryo Transfer

Background: Several reproductive biotechnologies are used in horses and embryo transfer (ET) is one of the most frequent in countries like Brazil and the USA. It has been shown that animals originated by new reproductive technology can have compromised growth in extreme conditions, however there are still only a few researches on the influence of embryo transfer over lactating foals under different raising methods. Due to the lack of studies on ET products development and the need to understand the process and it’s relate with lactating foal’s growth, the aim of this study was to evaluate the influence of the embryo transfer and natural mate over the newborn foals.Materials, Methods & Results: From a group of 20 mares, 20 Quarter Horse lactating foals were used (10 natural matting + 10 embryo transfer). The mares weren’t given any concentrate feed during whole gestation and lactation. Foals were kept with the mare, however was used creep feeding to give commercial feed ad libitum. The foals biometric evaluation were made at the day of birth (day 0) and at 30th, 60th, 90th, 120th and 150th day (weaning) for the following parameters: body mass (BM), height at the withers (H), heart girth (HG), cannon bone girth (CBG) and fat mass percentage (FMP). The fat thickness percentage at rump it was determined by ultrasound device. All statistics were considered significant when a P 0.05) and so did foals at birth (P > 0.05). However, by the time of weaning, body mass (BM) was 25% higher on ET foals group. These results indicate some influence of ET on foals’ growth since milk’s composition on both groups (G-NM and G-ET) was similar (P > 0.05), as well as dietary and sanitary handling that foals and mares were submitted to. It is a fact that one’s phenotype is determined not only by its genotype, there is evidence that environmental modification during intra uterine period, as well as extra uterine environment may affect epigenetic features. Changes of physical and skeleton progress patterns on suckling foals remained after weaning. However it could be observed that the present study foals had their development under proposed parameters according to prior studies, which affirm that animals have to duplicate their birth weight at the first month of age and should be five times higher at weaning. It stands out that ET treatment foals reported slightly high values indicating this research and future studies relevance to assure if growth beyond observed commonly is beneficial or damaging. In conclusion, there is little influence of the reproductive method over the lactating foal’s development when we compered two groups of foals obtained from natural mate and embryo transfer. However, foals from embryo transfer had large body mass at weaning when compared with natural mate group. Finally, the mares’ milk composition was similar between both groups of mares used in this study

Effects of L-Arginine Supplementation on Lactating Mares and the Development of Foals

Background: Most animal species are able to produce Arginine (Arg) under normal conditions. However, in some situations, its degradation can be higher than its production. For example, during a period of lactation or disease, there is an increase in the consumption of Arg. In this case, endogenous production is not enough for the animal’s demands. Indeed, Arg supplementation in animals has several benefits for the animal’s body, such as the increase of angiogenesis, improvements in immunity and the reproductive system, as well as the stimulation of lactogenesis. During the early phase of growth, a deficiency of Arg could cause a reduction in the growth rate and metabolic activity of animals. Therefore, this amino acid is considered essential in some phases of the life of animals. However, very few studies of the supplementation of this amino acid in horses have been carried out. The aim of the present study was to characterize the effects of supplementing lactating mares and their foals with Arg.Materials, Methods &amp; Results: Lactating mares (n = 10) were divided into two groups (control group: n = 3 / supplemented group: n = 7) and maintained exclusively under grazing. The supplemented group received 50 g of Arg during the lactation period. Samples of milk and blood from mares and blood from foals were collected at different phases of the lactation period. The following parameters were measured in milk: Glutamine (Gln); Glutamate (Glu); protein; fat; casein; lactose; urea and total solids. The following parameters were measured in blood: Gln; Glu; total plasmatic protein (TPP); albumin; urea; creatinine; uric acid; triglycerides; total cholesterol; calcium (C); phosphorous (P); magnesium (Mg) and ferrous (Fe). In addition, the biometric parameters of Wither Height (WH), Chest Perimeter (CP), Cannon Bone Circumference (CBC) and Fat Percentage (FP) of foals were obtained. A significant increase of Gln was observed in the milk in both groups (P &lt; 0.05). The highest concentration of Gln was detected in the third month of the lactation period in the supplemented group (~ 2.26 mmol/mL), and the control group (~ 1.91 mmol/mL) during the same period. Gln did not alter in the blood (P &gt; 0.05), although Glu was higher in the control group in the first month of the lactation period (~ 0.21 mmol/mL) (P &lt; 0.05). An increase in uric acid (~ 0.19 mmol/L) in both groups on the day of birth (P &lt; 0.05). In the supplemented group, increases in triglycerides (~ 0.60 mmol/L), Ca (~ 2.90 mmol/L) and Mg (~ 0.52 mmol/L) were observed in the first month of the lactation (P &lt; 0.05). At birth, foals exhibited high levels of urea (~ 4.67 mmol/L) and uric acid (~ 0.21 mmol/L), and low levels of P (~ 2.02 mmol/L) (P &lt; 0.05). The levels of Gln in the blood of foals remained between 0.50 and 0.70 mmol/mL throughout the lactation period (P &gt; 0.05). Even when they were added (Gln + Glu), no differences were observed (P &gt; 0.05). However, when the biometric parameters were analyzed, significant variations were detected in almost all characteristics (weight, WH, CP and CBC). In particular, the control group exhibited higher body mass and CP in the fifth month, when compared with the group of foals born from supplemented mares (P &lt; 0.05). The FP did not alter in either of the groups analyzed (P &gt; 0.05).Discussion: The results indicate that the supplementation of lactating mares with Arg produced few alterations in the parameters analyzed for both mares and foals. In addition, the supplementation did not produce side effects among the supplemented animals