Arabian Geldings Research Articles

Evaluation of two models of saddles on the back of Arabian horses through thermography

Dorsopathies are common causes of decreased performance in athletic horses of various modalities, and inadequate or poorly adjusted saddles can lead to the onset of injuries and low back pain. The present study, searching to find the most appropriate saddle, evaluated the pressure determined from the panels of two saddle models most commonly used in endurance Arab horse on the thoracolumbar region. For the study, six Arabian geldings were used, weighing 390 ± 4.2 and 2.1 ± age 8 years, conditioned to endurance races, and two saddle models, English and Western. The horses were submitted to the work riding on a sandy lane by the same experienced rider who weighed 76 kg. Thermography was performed before and after each exercise session. The obtained data were analyzed through Student’s paired t-test at 5% of significance. After exercise, there was a mean temperature difference between the contact areas of the right and left of the sweepers of two saddles compared, with the English saddle showing higher temperatures. Therefore, the Western saddle model, which has wider panels, despite not being a preferred model of endure riders, has proved to be more suitable for Arabian horse work.

Effect of yeast supplementation on digestibility, fecal microbiota and serum endotoxin levels in non-exercising and exercising horses

The aim of this study was to evaluate the effect dietary supplementation of live yeast Saccharomyces cervisiae NCYC 996 (SC) on digestibility, fecal microbiota and volatile fatty acids (VFA) and serum endotoxin levels in non-exercising and exercising horses. Ten Arabian geldings were used in a 2 × 2 factorial design [10 horses, 2 treatments (with and without SC) and 2 periods (with and without exercise). The SC culture (7.5g/meal; 1.5 × 1010cfu/g) was given as a top-dressing. There was no effect of yeast supplementation on digestibility. Fecal yeast and bacterial counts, VFA and serum endotoxin levels were unaffected by yeast supplementation and exercise.

Use of fats in the diet of sport horses has its pros and cons

Received: 2015-11-03 | Accepted: 2015-11-26 | Available online: 2016-03-24 dx.doi.org/10.15414/afz.2016.19.01.03-06 In this work, we have focused on the use of fats in the diet of sport horses. We watched the fat, and his effect as an energy source. But we watched also the influence of fat additions and their potential impact on the metabolic conversion of other received nutrients. For the addition of fat, we used evening primrose oil - EPO by which can be assumed to influence the metabolism in the body of sport horses. The 16 weeks experiment was performed on clinically healthy racehorses. All the horses were enrolled in a regular training program. Addition of EPO was 150 g per day. The blood samples were collected every 4 weeks during the experiment. There were analysed a selected biochemical parameters. Values of glucose and cholesterol were after administration of EPO significantly higher. Keywords : evening primrose oil, sport horses, glucose, TAG, cholesterol References ART, T. and LEKEUX, P. (2005) Exercise-induced physiological adjustments to stressful conditions in sport horses. Livestock Product. Sci. 92, pp. 101-111. doi: http://dx.doi.org/10.1016/j.livprodsci.2004.11.013 BERGERO, D. et al. (2004) Effect of dietary polyunsaturated fatty acids and vitamin E on serum oxidative status in horses performing very light exercise. Ital. J. of Anim. Sci ., vol. 3, pp. 121-145. DE LA CRUZ, J.P. et al. (1997) Effect of evening primrore oil on platelet aggregation in rabbits fed an atherogenic diet. Thrombosis Research , vol. 87, pp. 141-149. doi: http://dx.doi.org/10.1016/S0049-3848(97)00113-8 ESTERBAUER H. and ZOLLNER H. (1989) Methods for determination of aldehydic lipid peroxidation products. Free Radicals Biology and Medicine , vol. 7, pp.197-203. GOMES, E.C., SILVA, A.N. and DE OLIVEIRA M.R. (2012) Oxidants, antioxidants, and the beneficial roles of exercise – induced production of reactive species. Oxidative Medicine and Cellular Longevity. vol. 2012, pp. 12. doi: http://dx.doi.org/10.1155/2012/756132 KINNUNEN, S. et al. (2005) Effect of prolonged exercise on oxidative stress and antioxidant defence in endurance horse. J. of Sports Sci. and Medecine , vol. 4, pp. 415-421. MEYER, H. and COENEN, M. (2002 ) Pferdefutterung. Berlin: Parey Verlag . 250 p. NATIONAL RESEARCH COUNCIL OF THE NATIONAL ACADEMIES COMMITTEE ON NUTRIENT REQUIREMENTS OF HORSE . (2007). Nutrient requirements of horse: Animal nutrition series. 6th rev. edition. Washington: National Research Council National Academies Press. doi: http://dx.doi.org/10.17226/11653 PAGAN, J.D. et al. (2002) Effect of adaptation on glucose kinetics and substrate oxidation during low-intensity exercise. Equine Veterinary J ., 34. pp. 33-38. SAS Institute Inc. (2003) The SAS System for Windows . Release 9.1.3. SEN, C.K. and PACKER, L. (2000) Thiol homeostasis and supplements in physical exercise. American Journal of Clinical Nutrition , vol. 72, pp. 653-669. TREIBER, K.H. et al. (2013) Dietary energy source affects glucose kinetics in trained arabian geldings at rest and during endurance exercise. The J. of Nutrition, vol. 138, pp. 964-970. WETTASINGHE, M. and SHAHIDI, F. (2002) Iron (II) chelation activity of extracts of borage and evening primrose meals. Food Research International , vol. 35, no.1, pp. 65-71. ZEMAN, L. et al. (2005) Nutrient requirements and nutritive value of feeds for horses . Brno: Mendel University, pp. 116.

Effect of Two Different Commercial DNA Extraction Kits on the Bacterial 16S Ribosomal RNA Gene Denaturing Gradient Gel Electrophoresis Profile of Arabian Gelding Feces

The objective of this pilot study was to compare the effect of two commercial DNA extraction methods influenced the denaturing gradient gel electrophoresis (DGGE) banding patterns of the fecal microbiome of adult Arabian geldings. The quality of extracted DNA appeared low per spectrophotometric analysis; however, DNA amplification did not appear to be adversely effected. The fecal 16S ribosomal RNA DGGE profile of Arabian geldings between and within samples differed depending on the DNA extraction kit used.

Effects of phytase supplementation in mature horses fed alfalfa hay and pelleted concentrate diets

An experiment was conducted to study P digestibility in mature horses because of the growing environmental concerns regarding P runoff and previous equine research focused mostly on young and growing animals or used ponies as a model. Phytase supplementation of swine and poultry diets can result in greater phytate-P digestibility, leading to a decreased need for inorganic P supplementation and a decrease in P excreted to the environment; this, however, has not been demonstrated in the horse. Six mature Arabian geldings were fed 6 diets consisting of pelleted concentrate and alfalfa hay. The concentrates consisted mainly of soybean hulls, ground corn, wheat midds, broken rice, and beet pulp, and phytase was added to the concentrates accordingly before pelleting. There were 3 diet types: control (concentrate and hay), high P (greater P concentrate and hay), and forage only, and each diet type included 1 phytase-supplemented diet and 1 non-phytase-supplemented diet, resulting in 6 total diets. Phytase supplementation for the forage only diet was accomplished by feeding a nominal amount of concentrate formulated solely as a vehicle for the phytase. Horses had unrestricted access to water throughout the experiment. Using a Latin square design, all horses received all diets over a period of 12 wk. In each week, the new diet was fed for 11 d of diet acclimation, which was followed by a 3-d total collection of feces and urine for each horse. There was no effect (P < 0.05) of phytase supplementation on P output in the urine or feces, resulting in no differences in P apparent digestibility. Analysis of the feed and feces for phytate revealed a 93% average disappearance rate of phytate, indicating that horses are highly capable of degrading phytate and that phytase supplementation was not beneficial. Thus, the results indicate that mature horses are able to maintain a near 0 P balance, with adequate P provided in the diet even as phytate, and increased P intakes above requirement may result in increased potentially detrimental outputs to the environment.

Equine subepithelial keratomycosis

To describe clinical findings in equine subepithelial keratomycosis (SEK). Retrospective medical records study. Medical records of horses that had subepithelial keratomycosis (SEK) at the University of Florida Veterinary Medical Center from 2007 to 2011 were reviewed. Data collected from the medical records included signalment, clinical descriptions of ocular lesions, diagnostic techniques, and therapeutic outcomes. Twenty-one horses, consisting of three Quarter horse geldings, two Morgan geldings, one Morgan mare, two Arabian mares, three Arabian geldings, two warm blood mares, two warm blood geldings, two Thoroughbred geldings, one Thoroughbred mare, one Appaloosa mare, one Holsteiner gelding, and one Holsteiner mare with SEK were identified. Multifocal punctate and/or geographic patterns of subepithelial opacification were present in all eyes. Intermittent phases of weak fluorescein and/or rose Bengal dye were found in 16 eyes. Clinical signs of iridocyclitis were absent in all eyes. Cytologic confirmation of fungi was found in ten cases, Candida was cultured from one eye, and Aspergillus cultured in three eyes. Nineteen of 21 eyes with SEK resolved when topical antifungal therapy was initiated. Two of the 19 responding eyes recurred and required additional therapy, and two other eyes progressed to ulcerative keratomycosis. This is the first clinical report of a subtle form of keratomycosis in the horse. Subepithelial keratomycosis may be a distinct clinical entity or represent a continuum in the described forms of equine keratomycosis.

Protein quality and utilization of timothy, oat-supplemented timothy, and alfalfa at differing harvest maturities in exercised Arabian horses

To evaluate the protein quality and postgut N utilization of full-bloom timothy hay, oat-supplemented timothy-hay diets, and alfalfa hay harvested at different maturities, apparent whole tract N digestibility, urinary N excretion, and serum AA profiles were determined in light to moderately exercised Arabian horses. Six Arabian geldings (16.0 ± 0.3 yr; 467 ± 11 kg of BW) were randomly allocated to a 6 × 6 Latin square design. Diets included full-bloom timothy grass hay (G), G + 0.2% BW oat (G1), G + 0.4% BW oat (G2), mid-bloom alfalfa (A1), early-bloom alfalfa (A2), and early-bud alfalfa hay (A3). Forages were fed at 1.6% of the BW of the horse (as-fed). Each period consisted of an 11-d adaptation period followed by total collection of feces and urine for 3 d. Blood samples were taken on d 11 for analysis of serum AA concentrations. During the 3-d collection period, urine and feces were collected every 8 h and measured and weighed, respectively. Approximately 10% of the total urine volume and fecal weight per period was retained for N analyses. Fecal DM output was less (P < 0.05) in A1, A2, or A3 compared with G, G1, or G2. Apparent whole tract N digestibility was greater (P < 0.01) in A1, A2, and A3 compared with G, G1, or G2, and was greater (P < 0.05) in G1 and G2 compared with G. Nitrogen retention was not different from zero, and there were no differences (P > 0.05) in N retention among diets. Urinary N excretion and total N excretion were greater (P < 0.05) in A1, A2, and A3 compared with G, G1, or G2. Plasma concentrations for the majority of AA increased curvilinearly in response to feeding G, A1, A2, and A3 (quadratic, P < 0.05), with values appearing to maximize 2-h postfeeding. Although alfalfa N digestibility increased with decreasing harvest maturity, N retention did not differ and urinary volume and N excretion increased, indicating that postabsorptive N utilization decreased. In contrast, inclusion of oats at either 0.2 or 0.4% of the BW of the horse to timothy hay markedly enhanced N digestibility without increasing N excretion, indicating improvement in postgut N utilization. These findings indicate that feeding oat-supplemented timothy hay is more environmentally sustainable than feeding alfalfa to the horse at maintenance or under light to moderate exercise.

Effects of high and moderate non‐structural carbohydrate hay on insulin, glucose, triglyceride, and leptin concentrations in overweight Arabian geldings

The objective of this study was to determine the effects of high and moderate non-structural carbohydrates (NSC) hay on insulin, glucose, triglyceride, and leptin concentrations in overweight Arabian geldings. Eight adult overweight (average BCS 7 [9-point scale]) Arabian geldings were fed each of two orchardgrass hays, high NSC (18% DM) and moderate NSC (12% DM), in a cross over design during two 28-day periods. Body weight and body condition score assessment along with blood sampling to measure insulin, glucose, leptin, and triglyceride concentrations were performed on days 0, 7, 14, 21 and 28 of each period. Effects of hay, period, day, and day*hay on plasma glucose and serum leptin were not detected. Serum insulin was influenced by hay (p = 0.001), day (p = 0.03), and day*hay (p = 0.04). Insulin concentrations were higher on day 7 in the high NSC group (15.6 μIU/ml) than the moderate NSC group (9.5 μIU/ml), but not by day 14 (p = 0.0007). Plasma triglyceride was influenced by period (p = 0.0003), day*period (p < 0.0001), and day*hay (p = 0.02). Hyperinsulinaemia was not observed in the overweight Arabian geldings fed either a moderate or high NSC hay.

Single‐injection glucose kinetics with compartmental modelling during rest and low‐intensity exercise in horses

Tools and criteria to evaluate and understand glucose metabolism are essential to optimise equine energy utilisation for exercise performance and reduced metabolic health risks. To re-evaluate models of glucose kinetics in the horse at rest and during endurance type exercise using a single injection technique and compartmental modelling. Twelve exercise trained Arabian geldings received a bolus of 100 µmol/kg bwt [6,6-(2) H]glucose i.v. while at rest and while running at ∼ 4 m/s on a treadmill. Tracer and tracee glucose curves from 4-150 min after the bolus dose (while the subject maintained its resting or exercising state) were described by a 2 term exponential decay curve. Compartmental modelling was performed simultaneously for each horse's resting and exercise curves using an 'exercise effect' parameter for each compartmental exchange rate during exercise. Exercise increased all rate constants and transport flows for glucose between compartments by 110-145% (P ≤ 0.004). Total glucose transport through the system increased from 8.9 ± 0.6 µmol/min/kg/bwt at rest to 25.0 ± 1.1 µmol/min/kg bwt during exercise (P < 0.001). Exercise decreased the volume of the primary glucose compartment by 8% (P = 0.006) and increased plasma glucose clearance rate by almost 200% (P < 0.001). Turnover times and mean residence times were decreased approximately 60% by exercise (P < 0.001), whilst turnover rates were increased 125% (P < 0.001). Single-injection tracer kinetics and compartmental modelling represent a valuable tool to quantify tracee availability to and use by tissue. This technique could represent a beneficial tool for future studies exploring the role of glucose metabolism in equine exercise performance and metabolic disease.

Dietary supplementation with short-chain fructo-oligosaccharides improves insulin sensitivity in obese horses1

Obesity and insulin resistance are risk factors for laminitis in horses and ponies, and diet can play an important role in modulating these risk factors. Dietary supplementation with prebiotic fibers, such as short-chain fructo-oligosaccharides (scFOS), has resulted in improvement of insulin sensitivity in obese dogs and rodents. Thus, we hypothesized that scFOS may reduce insulin resistance in obese horses and designed a study to evaluate the effect of dietary supplementation with scFOS on insulin sensitivity. Eight mature Arabian geldings (BW = 523.0 ± 56.5 kg) with an average BCS of 8 were included in a crossover study. In each period, 4 horses were provided 45 g/d per horse of maltodextrin (control) and 4 horses received the same amount of scFOS for 6 wk, with a 3-wk washout between periods. Resting plasma concentrations of glucose, insulin, triglycerides, and leptin were measured. Minimal model analysis of a frequently sampled intravenous glucose tolerance test was used to evaluate insulin sensitivity, glucose effectiveness, acute insulin response to glucose, and disposition index. Without affecting BW and BCS, dietary supplementation with scFOS increased (P < 0.05) insulin sensitivity and reduced (P < 0.05) acute insulin response to glucose in comparison with maltodextrin but did not alter (P > 0.05) glucose effectiveness and disposition index. Resting serum insulin concentration also was reduced (P < 0.05) by scFOS supplementation but not by maltodextrin (P > 0.05). There was no effect (P > 0.05) of scFOS supplementation on plasma glucose or serum triglyceride and leptin concentrations. This study demonstrated that scFOS can moderately improve insulin sensitivity of obese horses, a finding that has potential relevance to the dietary management of obese, insulin-resistant horses at increased risk for laminitis.

Dietary Energy Source Affects Glucose Kinetics in Trained Arabian Geldings at Rest and during Endurance Exercise ,

Advances in modeling and tracer techniques provide new perspective into glucose utilization and potential consequences to health or exercise performance. This study used stable isotope and compartmental modeling to evaluate how adaptation to a feed high in sugar and starch (SS) compared with a feed high in fat and fiber (FF) affects glucose kinetics at rest and during exercise in horses. Six trained Arabians adapted to each feed underwent similar tests at rest and while running ∼4 m/s on a treadmill. For both tests, horses received 100μmol/kg body weight [6,6-2H]glucose through a venous catheter. Circulating tracer glucose was described for 150 min by exponential decay curves and compartmental analysis. All parameters of glucose transfer increased with exercise (P ≤ 0.004). Compared with FF horses, SS horses had higher circulating glucose (P = 0.022) and fractional glucose transfer rates (min−1) at rest (P = 0.055). Exercise increased glucose irreversible loss (mmol/min) more in SS horses (P = 0.037). Total glucose transfer during exercise tended to be greater in SS horses (0.027 ± 0.002 mmol/min) compared with FF horses (0.023 ± 0.002 mmol/min) (P = 0.109). This study characterized the effect of diet on glucose kinetics in resting and exercising horses using new modeling methods. Horses adapted to a fat-supplemented feed utilized less glucose during low-intensity exercise. Fat supplementation in horses may therefore promote greater flexibility in the selection of substrate to meet energy demands for optimal health and performance.

Apparent adiposity assessed by standardised scoring systems and morphometric measurements in horses and ponies

This study described a scoring system for the assessment of apparent neck adiposity and evaluated morphometric measurements for assessment of neck and overall adiposity. Twenty-one barren Thoroughbred mares, 13 Arabian geldings and 75 Welsh, Dartmoor, or crossbred pony mares, were clinically examined and blood samples analysed for insulin, glucose, leptin, and triglycerides. Bodyweight (BW), height, length, girth and abdominal circumferences, neck length, neck crest height and neck circumference were measured, and body condition scores (BCS) and cresty neck scores (CNS) were rated. Girth:height ratio had the strongest associations with BCS ( r s = 0.64, P < 0.001 in horses; r s = 0.83, P < 0.001 in ponies) and blood variables, such as leptin ( r s = 0.39, P = 0.024 in horses; r s = 0.68, P < 0.001 in ponies). Crest height and neck circumference:height ratio had the strongest association with CNS ( r s > 0.50, P < 0.01) and blood variables, such as insulin ( r s ⩾ 0.40, P < 0.05). Cresty neck score was useful in the assessment of neck crest adiposity and had physiological relevance, as demonstrated by associations with blood variables. Girth:height was the most suitable morphometric for assessment of overall adiposity, and either crest height or neck circumference:height was a suitable morphometric for assessment of apparent neck adiposity.

Cellulase Supplementation Does Not Improve the Digestibility of a High-Forage Diet in Horses

Abstract Six mature Arabian geldings were used in a two-period crossover study to investigate the effects of cellulase supplementation on fiber digestion. Horses were randomly assigned to either a control (CO; n = 3) or a cellulase (CE; n = 3) treatment for the first period and then treatments were switched for period 2. Each period consisted of a 10-day diet adaptation followed by a 3-day total fecal collection. The enzyme mixture contained 40,000 cellulase units/g and was fed at a rate of 3 g/day split evenly between two feedings. During the diet adaptation period, horses had ad libitum access to timothy hay and were also fed 165 g whole oats as a carrier for the supplement. When eating the CO treatment, horses consumed 16% more hay than when on the CE treatment (P = .004). Fecal output also tended to be greater when horses consumed the CO treatment as compared with CE treatment (P = .07). No differences were found between treatments for fecal percent dry matter (DM%), fecal neutral detergent fiber (NDF), fecal acid detergent fiber (ADF), fecal nitrogen (N), or fecal gross energy (GE). There was a trend for horses consuming the CO treatment to digest more NDF than when consuming the CE treatment (34.6% ± 1.5 vs 31% ± 1.5; P = .07). Horses also digested a greater %ADF, %N, and Mcal of energy when consuming the CO treatment than when consuming the CE treatment (P

Glucose kinetics in trained Arabian geldings: effects of dietary energy source and endurance exercise

Glucose kinetics in trained Arabian geldings: effects of dietary energy source and endurance exercise

Glucose dynamics during exercise: dietary energy sources affect minimal model parameters in trained Arabian geldings during endurance exercise

Glucose regulation is critical for health and exercise performance. To quantify the effects of exercise and diet on insulin sensitivity (SI), glucose effectiveness (Sg), acute insulin response to glucose (AIRg) and disposition index (DI) in horses. This study applied the minimal model of glucose and insulin dynamics to exercise-trained Arabian geldings during rest or constant moderate-intensity exercise after 8 weeks adaptation to feeds high in sugar and starch (SS, n = 6) or fat and fibre (FF, n = 6). Horses underwent 2 frequently sampled i.v. glucose tolerance tests (FSIGT). For both tests, a resting basal sample was collected, followed by an i.v. dose of 600 mg/kg bwt glucose defining 0 min of the test. Insulin (0.01 iu/kg bwt) was administered 20 min post glucose for each test. Resting horses were sampled for 240 min. The exercise FSIGT began after each horse had warmed-up for 25 min on the treadmill at which point they had reached the speed representing 60% of their predetermined lactate breakpoint maintained for the rest of the FSIGT. Exercising horses were sampled identically to rest, but for only 150 min post glucose. Exercise increased (P<0.008) SI, Sg and DI and decreased AIRg in all horses. Overall, horses adapted to FF tended to have higher SI (P = 0.070) and DI (P = 0.058). During exercise, FF horses tended to have higher (P< or =0.085) SI and DI, than SS horses and these variables tended to be increased more (P< or =0.075) by exercise in FF horses than SS horses. Insulin and glucose dynamics adjust during exercise, increasing plasma glucose uptake, presumably to meet demand by contracting skeletal muscle. Trained horses adapted to a high fat diet showed greater metabolic adjustment during exercise than trained horses adapted to a high starch and sugar diet, potentially allowing them to better meet energy demands. Nutrition and exercise impact glucose and insulin dynamics, potentially influencing health and performance.

Dietary energy sources affect insulin sensitivity and β‐cell responsiveness of trained Arabian geldings during endurance exercise

Adaptation to diets which replace carbohydrates with fat as an energy source have been shown to avoid insulin resistance and improve metabolic regulation during exercise. This study compared the effects of diet and moderate‐intensity exercise on glucose and insulin concentrations in 12 trained Arabian geldings. Six Arabians were adapted for 8 weeks to a feed high in sugar and starch (SS) and six were adapted to a feed rich in fat and fibre (FF). All horses were exercise‐trained prior to and throughout feed adaptation. Horses were sampled between 0900 and 1000 h at rest and during moderate‐intensity exercise on a treadmill at 57% of their lactate threshold following 25 min of warm‐up. Plasma was analysed for glucose and insulin. Basal proxies for insulin sensitivity (LRIB = log[100/basal insulin]) and pancreatic β‐cell response to circulating glucose (MIRG = log[(100·basal insulin)/(basal glucose – 50 mg/dL)]) were calculated. Basal insulin tended to be lower in FF adapted horses (p = 0.068) and was lower during exercise as compared to rest in FF horses (p = 0.013) but not SS horses (p = 0.44). Plasma glucose concentration was lower in FF horses (p &lt; 0.001) and increased during exercise for SS adapted horses (p = 0.015) but not FF horses (p = 0.38). Insulin sensitivity as determined by LRIB was higher during exercise (p = 0.019) for all 12 horses while β‐cell response as determined by MIRG was lower (p = 0.006). Arabians adapted to the FF diet also had higher LRIB (p = 0.047) but diet had no affect on MIRG (p = 0.20). Exercise tended to increase (p = 0.11) LRIB more in FF horses (34%) than SS horses (11%). These differences indicate that horses adapted to high carbohydrate diets have lower insulin sensitivity and impaired metabolic regulation involving insulin signalling. These effects are avoided in horses adapted to the FF feed, with potential benefits to their health and endurance exercise performance.

Effect of partial replacement of oats with sugar beet pulp and maize oil on nutrient utilisation in horses.

The objective of the present work was to assess the influence of partial replacement of oats with dried unmolassed sugar beet pulp (SBP) and/or maize oil on nutrient utilisation in horses fed a traditional hay and concentrate diet. The total tract digestibility of nutrients, urinary excretion and plasma parameters were studied in a 4 x 4 Latin-square design experiment with purebred Arabian geldings. Horses fed the SBP diets responded with a reduced (P<0.05) apparent digestibility of crude protein and feeding of maize oil resulted in an increased (P<0.05) apparent digestibility of crude fat. The apparent energy digestibility was unaffected by the replacement of oats with SBP, but increased (P<0.05) when maize oil replaced part of the oats. The urinary excretion of nitrogen increased (P<0.05) when maize oil replaced oats and the excretion of energy was higher (P<0.05) on the diets where oats were replaced by maize oil and SBP. There was a significant (P<0.05) effect across treatments of postprandial blood sampling time on plasma glucose and insulin concentrations. Also, plasma concentrations of glucose and insulin tended to be higher on the oats than on the SBP diets. In conclusion, the limited effects on the digestibility of nutrients and energy suggest that it should be possible to partially replace oats with maize oil and/or SBP in diets for horses without any impairing effects on the overall nutrient utilisation. However, the dietary-induced changes in the urinary excretion of energy and on plasma glucose and insulin levels, indicate a possible influence of dietary carbohydrate composition on nutrient utilisation at the organ level, which requires further study.

Carbohydrate Supplementation of Horses During Endurance Exercise: Comparison of Fructose and Glucose

To delay the onset of fatigue, endurance horses are often fed at rest stops during races. The resulting increase in blood insulin may adversely inhibit lipolysis. In humans, ingestion of fructose produces a smaller insulin rise than glucose. This study compared glucose and fructose as carbohydrate supplements for endurance horses. Three Arabian geldings were given 300 g of fructose (F), glucose (G) or 50% glucose: 50% fructose (GF), in 1.5 L water, by stomach tube. In the Resting Test, carbohydrate was administered at rest. Following treatment, blood samples were taken every 30 min for 8 h, and feces were collected for 24 h. Treatment did not affect fecal weight or water content. Plasma glucose and insulin responses did not differ among treatments. Post-treatment (60 min), plasma L-lactate tended to be higher (P = 0.06) after the F and GF treatments than after the G treatment. In the Exercise Test, two treadmill exercise bouts at 0 degrees incline (Bout 1: 90 min; Bout 2: 120 min) were separated by a 1-h rest period. A total distance of 36.84 km was covered at a mean speed of 2.9 m/s. Carbohydrate was administered 45 min before Bout 2. Plasma glucose and insulin at the start of Bout 2 were higher (P = 0.02 and 0.03, respectively) with the GF treatment than with the F treatment. However, during exercise, plasma glucose concentrations did not differ among treatments. We conclude that fructose is well-absorbed by horses and rapidly converted to glucose.

Free Fatty Acids in Exercising Arabian Horses Fed Two Common Diets

Four Arabian geldings were used in a randomized, repeated measure design to study the effect of two different diets on plasma free fatty acids at rest and during exercise. On each of four sampling days, two horses were fed one of two isoenergetic diets, either 100% corn or 100% alfalfa, at 22% of their estimated daily energy requirement. Two hours after the consumption of the diet, each horse participated in a submaximal standard exercise test consisting of three consecutive 10-min runs of increasing intensity at heart rates of 132, 140 and 147 beats/min, respectively. There were no significant (P > 0.05) differences between the two groups (com-fed vs. alfalfa-fed) in pre-meal (0.554 ± 0.031 vs. 0.629 ± 0.033 mmol/L), post-meal (0.520 ± 0.027 vs. 0.609 ± 0.041 mmol/L), and basal (0.392 ± 0.036 vs. 0.401 ± 0.052 mmol/L) free fatty acid concentrations. However, free fatty acids were significantly higher in the horses fed alfalfa (0.608 ± 0.038 mmol/L) rather than corn (0.484 ± 0.031 mmol/L) during exercise.