Nutrition in horses encompasses the study of dietary requirements and feeding practices that support equine health, growth, and performance. It involves the analysis of nutrients such as carbohydrates, proteins, fats, vitamins, and minerals, and their roles in equine physiology. Proper nutrition is essential for maintaining optimal body condition, supporting metabolic processes, and preventing dietary-related disorders. Research in this field examines the nutritional needs of horses at different life stages and activity levels, as well as the effects of various feed types and supplements. This page compiles peer-reviewed research studies and scholarly articles that explore the composition, digestion, and impact of different dietary components on equine health and performance.
Rose RJ, Kohnke JR, Baggot JD.Plasma phenylbutazone concentrations were determined for up to 12 h in 6 horses following intravenous and oral phenylbutazone administration. To evaluate the bioavailability of different oral preparations, phenylbutazone was administered in a paste as well as the traditional powder form. The effect of the state of stomach contents on the absorption of phenylbutazone was investigated by administering the paste before and after feeding; the powder was given in a small bran mash and a full feed of lucerne chaff, wheaten chaff and bran. Despite great variability among individual horses both the pa...
Ford EJ, Evans J.1. Total entry, irreversible loss and recycling rates of glucose were measured in four non-pregnant female Shetland ponies before and after a 24 h fast by the continuous intravenous infusion of a mixture of [U-14C]glucose and [2-3H]glucose. 2. The post-fasting fall in the concentration of glucose and the rise in the concentration of ketones in plasma were not significant. 3. After fasting the total entry rate fell from 1.44 +/- 0.11 (n4) to 1.19 +/- 0.12 mg/min per kg body-weight (P less than 0.01) and irreversible loss fell from 1.36 +/- 0.10 (n4) to 1.05 +/- 0.10 mg/min per kg body-weight (P...
Luther DG, Cox HU, Dimopoullos GT.Fatty acid composition of erythrocytes of healthy horses was determined. Three fatty acids (C16:0, C18:0, and C18:1) were found in approximately equal quantities and comprised 72.17% of the total. Nine other fatty acids were found in small amounts. Saturated fatty acids constituted 67.2% of the total. Marked variation was demonstrated in the occurrence and distribution of fatty acids in the sterol ester, triglyceride, phospholipid, and free fatty acid fractions.
Ralston SL, Baile CA.The hypothesis that changes in blood glucose concentrations and(or) utilization rate affect feeding behavior in ponies was tested. Ponies (n = 4) were fasted for 4 h, then given iv injections of 50% glucose [.2 g glucose/BW.75 kg (low dose, LD) or 1.0 g glucose/BW.75 kg (high dose, HD)] or an equal volume of normal saline (HDS; LDS) 5 min before being allowed access to pelleted feed. Blood samples were drawn at regular intervals pre- and post-treatment and analyzed for plasma glucose (PG), immunoreactive insulin (IRI) and glucagon concentrations. All glucose-treated animals immediately ate mea...
Parodi PW.Milk triglycerides from the echidna, koala, Tammar wallaby, guinea pig, dog, cat, Weddell seal, horse, pig and cow were subjected to fatty acid and stereospecific analysis to determine the positional distribution of the fatty acids in the triglycerides. The samples presented a wide range of fatty acids, most of which varied in content among species. The compositions of the acids at the 3 positions also varied among species, reflecting the content of these acids in the triglycerides. However, there was a general similarity in fatty acid positional distribution patterns for all the species with ...
Gronwall R, Engelking LR.The effects of several treatments and their routes of administration on the reduction of hyperbilirubinemia in 9 pony mares after a 3-day fast were studied. Treatments were as follows: glucose given at doses of 1.2, 2.4, and 3.7 mg/min/kg of body weight; refeeding the base-line diet; feeding straw; and IV administration of taurocholic acid at a dosage of 0.07 mumol/min/kg. The 3 glucose dosages were each given by 3 different routes: IV, intraduodenal, and intragastric. The smallest dosage of glucose given by IV route reduced the plasma bilirubin concentration only 7%, even though other measure...
Meijer P.Two cases of tetany in the horse are reported. The two patients were thoroughbreds. One was eight and the other thirteen years old. The mares were in heat and were brought to the service (stud) station to be mated. Both patients were nursing a foal. One was a four-week-old foal and the other was seven weeks old. The calcium level of the serum had dropped in the two patients, to 4.0 mg and 5.4 per ml. respectively. The magnesium level was 1.0 mg and 1.9 mg per 100 ml. respectively. The animals responded satisfactorily to intravenous infusion of calcium borogluconate and magnesium chloride. One ...
Jacobs KA, Bolton JR.The effect of altering the diet during the week preceding the administration of an oral glucose tolerance test was studied in 7 horses. The results indicated that substantially lower oral glucose tolerance test curves are observed in horses fed a stable diet comprised of oat hay, a commercially prepared complete feed, and oat and alfalfa chaff, when compared with the curves for horses grazing clover and kikuyu pasture. It was concluded that, in utilizing the oral glucose tolerance test to assess small intestinal function in the horse, it may be necessary to consider the dietary history.
Harrington DD.Acute accidental vitamin D2 (ergocalciferol) toxicosis was diagnosed in a 6-month-old foal with extensive lesions of soft tissue mineralization. In an experimental study, three 18-month-old horses were given ergocalciferol per os at a rate of 9,300, 22,200, or 47,200 IU/kg of body weight/day for 21 days. Clinical signs or lesions were not seen in horses given the low and intermediate doses, whereas the horse receiving the highest dose developed clinical signs and lesions similar to those noted in the foal. Signs included depression, loss of appetite, weakness, limb stiffness with impaired mobi...
Canning JF.Bile flow, during feeding and fasting, was studied in three ponies in which catheters, maintained in the bile duct over 1-2 months, drained all bile continuously. During experiments bile was returned to the small intestine, via a second catheter, by means of a small pump which also measured bile flow rates. The mean +/- S.E. of the mean rate of bile flow in fed ponies with an intact enterohepatic circulation of bile salts was 1.33 +/- 0.10 ml/kg . h, n = 13; mean +/- S.E. of the mean concentration of bilirubin in bile was 10.82 +/- 0.91 mg/dl, n = 13. The effect on bile flow and bilirubin excr...
Caple IW, Bourke JM, Ellis PG.The calcium and phosphorus nutrition of thoroughbred racehorses was assessed by analysis of serum and urine samples collected from 90 horses in 1975 and 139 horses in 1980-81 at racetracks in Melbourne. Horses that were excreting greater than 15 mumole Ca/mosmole and which had a calcium to creatinine clearance ratio greater tha 2.5% were considered to have adequate Ca intake. Horses that were excreting greater than 15 mumole P/mosmole and which had a phosphorus to creatinine clearance ratio greater than 4% were considered to have excessive phosphorus intake. Sixty-percent of the horses sampled...
Blackmore DJ, Campbell C, Dant C, Holden JE, Kent JE.The activity of glutathione peroxidase (GSH-Px) was measured in the erythrocytes of 600 Thoroughbred horses in training; the selenium concentrations in whole blood and serum was measured in over 80 of these Thoroughbreds. A quadratic relationship was demonstrated between erythrocyte GSH-Px and whole blood or serum selenium concentration. There was no significant difference in the activity of aspartate aminotransferase, creatine kinase, or gamma-glutamyl transferase in the serum of Thoroughbreds with high erythrocyte GSH-Px activity (more than 25 u/ml) when compared with those with low erythroc...
Caple IW, Doake PA, Ellis PG.Studied were made to determine if a practical assessment of the calcium and phosphorus nutrition of horses could be obtained from an analysis of urine samples. The concentrations of Ca and P in urine samples changed markedly when groups of 4 mares were fed diets containing from 1.0 to 3.9 g Ca/kg and from 1.5 to 6.1 g P/kg, but serum concentrations of Ca and P remained relatively constant. The concentrations in single urine samples were considered unreliable indicators of excretion of the minerals because of variations in water excretion, and two methods to overcome this problem were examined....
Orlov VK, Servetnik-Chalaia GK.Physicochemical properties of fat and fatty-acid composition of mare's milk and shubath (sour milk product obtained from camel's milk) depend on the season. During summer these products show a higher content of fat and increased level of polyunsaturated fatty acids, particularly in mare's milk lipids. It has been shown that in mare's milk lipids 90% is due to acids with a carbon chain of C14-18, while shubath lipids contain almost 96% of such acids.
Udén P, Van Soest PJ.1. The abilities of cattle, sheep, goats, equines and rabbits to digest mature timothy (Phleum pratense) hay were compared. Apparent digestibilities were partitioned into true digestibility, metabolic faecal output (MFO) and fibre digestibility. The aid of the study was to determine the relative effects of fermentation site (among groups) and of body-weight (within groups) on the efficiency of digestion. 2. The ruminants were superior to equines, which were in turn superior to rabbits, in digesting fibre-components of the hay. A large individual variation in digestibility was noted only for th...
Rose RJ, Sampson D.Total and individual non-esterified fatty acids (NEFA), pyruvate, lactate, alpha ketoglutarate, acetoacetate, beta hydroxybutyrate, glucose and insulin were measured in horses during an 80 km endurance ride and during four days of food deprivation. In the latter group venous blood-gas and acid-base parameters, and plasma cortisol concentrations were also measured. During exercise and food deprivation the NEFA became considerably elevated, the predominant of which were oleic (35 per cent), palmitic (24 per cent), linoleic (19 per cent) and linolenic (10 per cent). By one hour after feeding tota...
Sklan D, Donoghue S.1. Serum and intracellular distribution of retinol was determined in equines maintained on four levels of vitamin A intake. 2. The form of retinol transported in serum was determined by gel filtration and chromatography to be a complex of retinol bound to a protein of molecular weight (MW) of approximately 20000, which was in turn complexed probably with prealbumin to yield a complex with a MW of 75000 to 80000. 3. Increasing dietary vitamin A levels enhanced the concentration of lipoprotein-bound retinyl esters in the plasma. 4. Vitamin A in the liver cytosol was found predominantly as retiny...
Gibbs PG, Potter GD, Blake RW, McMullan WC.Milk production was measured in fourteen Quarter Horse mares at seven stages of a 150-d lactation period. Mares were divided into two groups of seven and fed diets containing either soybean meal or soybean meal and urea as nitrogen supplements. Rations were isocaloric, contained approximately 12.5% crude protein and were fortified with vitamins and minerals. Daily milk yield was estimated by the weigh-suckle-weigh method and milk composition was determined from samples taken by hand milking. Average daily milk yield ranged from 11.8 kg in early lactation to 9.8 kg in late lactation. Difference...
Gunson DE, Kowalczyk DF, Shoop CR, Ramberg CF.Several suspect causes of chronic zinc/cadmium toxicosis in horses near a zinc smelter were investigated following observations of lameness, swollen joints, and unthriftiness, particularly in foals. Two foals born and raised near the smelter were lame and had joint swellings that were attributable to severe generalized osteochondrosis. Zinc and cadmium concentrations were markedly increased in the pancreas, liver, and kidney. The serum of 1 foal, zinc and potassium concentrations were high, whereas calcium and magnesium concentrations were low. Marked nephrocalcinosis and osteoporosis were obs...
Glade MJ, Krook L, Schryver HF, Hintz HF.Pony foals were injected intramuscularly with 0, 0.5, or 5.0 mg dexamethasone per 100 kg body weight daily for up to 11 months. True absorption of dietary calcium was inhibited by treatment at 18 days (57% versus 14% of intake; P less than .01) and 10 months (72% versus 55% versus 43%: P less than .01), but not at 2 or 7 months, and was independent of age and treatment related decreases in intestinal calcium binding protein activities. Uninary excretion of calcium was increased by treatment through 7 months but decreased at 10 months. Treatment for 18 days resulted in total calcium excretions ...
Stowe HD.Serum and milk samples from mares and serum samples from their foals were taken at parturition and on d 1, 2, 4, 7, 14 and 21 postpartum. The samples were assayed for retinyl (r.) palmitate, r. acetate and retinol by high performance liquid chromatography. Peak vitamin A activity in milk occurred 1 d postpartum and preceded by 3 d the maximum vitamin A activity in foal serum and the lowest vitamin A activity in the mare serum. Mare serum contained approximately a 65:35 ratio of retinol:r. palmitate and less than 1% r. acetate. Retinyl palmitate was the predominant form of vitamin A in milk unt...
Luthersson N, Harris PA, Parkin T, Þorgrímsdóttir ÚÝ, Bennet ED.It is unknown whether the high prevalence of Equine Squamous (ESGD) and Equine Glandular (EGGD) Gastric Disease in extensively grazed Icelandic horses in the autumn/winter is seasonally driven. Objective: To determine the prevalence of, and risk factors for, gastroscopically significant ESGD (ESGD:score of ≥2/4); gastroscopically severe ESGD (ESGD:score of ≥3/4) and gastroscopically significant EGGD (EGGD:score of ≥1/2) in extensively pasture-managed Icelandic horses at four timepoints. Methods: Prospective longitudinal cohort. Methods: Gastroscopy was undertaken in 80 Icelandic horses (...
Fowler AL, Pyles MB, Hayes SH, Crum AD, Lawrence LM.Total fecal collection studies to determine digestibility of nutrients are costly and laborious. The use of externally dosed indigestible markers, such as titanium dioxide (TiO2), to estimate digestibility using spot samples could be advantageous, but studies validating their use in horses are inadequate. Two experiments were conducted to determine if TiO2 in fecal spot samples effectively estimated fecal output in horses. In Exp. 1, four mature horses were fed a forage-based diet (85:15 forage: concentrate) split into two equal meals with 1.75 ± 0.03 g TiO2/kg DM (10 g TiO2) per day ...
Semanchik PL, Wesolowski LT, Artman JL, Seward RL, Beer C, Barnes ED, White-Springer SH.Reactive oxygen species are normal by-products of cellular metabolism but may have detrimental effects on cellular matrices and excite inflammatory pathways when overproduced. To test the hypothesis that supplementation of an herbal extract combination would: 1) improve antioxidant status; 2) increase anti-inflammatory cytokines; and 3) decrease pro-inflammatory cytokines, 40 mature, sedentary stock-type horses (32 mares, 8 geldings, mean±SD; 15.7 ± 4.9 yr, 519 ± 46 kg) were stratified by age, sex, and body weight and randomly assigned to one of four dietary treatment groups for 5...
Cermák O.The paper describes the relation of citric acid to other chemical and biological indices of the fertility of stallion sperm. A positive relation was found between citric acid and the density and motility of spermatozoa, to the concentration of ergothioneine, and hemolytic activity, and a negative relation to pH and to the polarographic activity of proteins. Attention is drawn to the important nutritional function of citric acid.
Trauner AM, McCoski SR, Satterfield MC, Bradbery AN.Reproductive health of male offspring following perturbations in maternal nutrition is not well-described in the horse; therefore, the objective of this study was to determine the effects of maternal overnutrition on neonatal foal testicular development. Sixteen Quarter Horse mares were used in a completely randomized design and stratified by expected foaling date, body weight, and body condition score into 1 of 2 dietary treatments beginning on gestational day 235: control (CON; n = 8) fed to meet nutrient requirements and overfed (HIGH; n = 8) fed 40% above CON. At 5 h postpartum, f...
Dickinson CE, Lori DN.In the absence of debilitating medical problems, the geriatric horse can maintain a normal body condition when provided with an appropriate diet, adequate shelter, and preventive health care that includes regular dental care and deworming. Failures in management can lead to inadequate nutritional support, exposure to adverse environmental conditions, advanced dental disease, parasitism, and failure to detect developing medical problems. All these circumstances can lead to loss of condition and debilitation in the aged horse. Weight loss in the aged horse should be approached with an understand...
Ferrante PL, Menninger JH, Spencer PA, Kronfeld DS.Four mares fed a low fiber, high soluble carbohydrate diet were used in a crossover design to evaluate the effects of dietary sodium bicarbonate (NaHCO3) supplementation during daily low-intensity submaximal working conditions. Mares were fed the diet at 1.7 times the maintenance energy requirement for mature horses at work. The horses tolerated the diet well and had no clinical abnormalities. Resting venous blood bicarbonate (HCO3), standard HCO3, and base excess (BE) concentrations significantly (P less than 0.05) increased with NaHCO3 supplementation, but no significant changes in resting v...
Stowe HD.The effects of 0.2, 0.4, 0.6, 0.8, 1.0 and 1.2% potassium, as K2CO3, in a purified diet were studied in orphaned foals of mixed breeding ranging in age from 11 to 57 days. Observations regarding feed intake, rate of gain, packed cell volume (PCV), erythrocyte counts (RBC), hemoglobin (Hb), leukocyte counts (WBC), and serum Na, K and Fe were made. Consumption of the 0.2% K diet after 8 days was inadequate to support growth. The foals consumed the 1.0 and 1.2% K diet at significantly higher rates (28.8 and 27.5 g/kg foal per day, respectively) than the 0.4% K diet. Rates of gain of foals fed 0.4...
Hallebeek AJ, Sloet van Oldruitenborgh-Oosterbaan MM.Small bumps or swellings of about 0.5 mm in diameter in the skin of horses are called 'haverbultjes' in the Netherlands. Comparable skin diseases described in the literature are 'sweet feed-, protein- and heat bumps'. The differential diagnosis and the possible nutritional causes of 'haverbultjes' are presented.
St Lawrence AC, Lawrence LM, Coleman RJ.Many studies have examined the effect of pre-exercise feeding on glucose and insulin responses of horses. The objective of this study was to determine whether exercise performed one hour prior to a meal would attenuate the glucose and insulin responses to a meal. Data collected from 8 mature geldings in a 2 period crossover design experiment were used to determine the postprandial glucose and insulin responses to a meal of oats offered 1 h postexercise. During each period, 4 horses received a test meal following a 14 h fast (NoEx) or a 14 h fast and exercise bout (PostEx) that consisted of 48 ...
Reitnour CM.Utilisation of nitrogen was studied in 4 crossbred ponies. A latin square design was used to study the effects of corn gluten meal, casein or urea when added to a low protein basal diet. Apparent nitrogen digestion, nitrogen retention, total plasma protein, plasma urea and plasma-free amino acids were measured. The addition of corn gluten meal, casein or urea to the basal ration increased apparent digestion of nitrogen. Casein produced a significantly greater (P less than 0.05) nitrogen retention than corn gluten meal or urea. Plasma urea nitrogen increased significantly (P less than 0.01) in ...
McKenzie EC, Firshman AM.Chronic exertional rhabdomyolysis represents a syndrome of recurrent exercise-associated muscle damage in horses that arises from a variety of etiologies. Major advances have been made in the understanding of the pathophysiology of this disease, and causative genetic defects have been recently identified for two conditions-polysaccharide storage myopathy of quarter horses, paints, warm bloods, and draft breeds. Dietary management in combination with a regular exercise regimen comprises the most effective means for control of clinical signs.
Jollès J, Donda A, Amiguet P, Jollès P.Mare lactotransferrin has been purified and analyzed. Its molecular mass is 81 kDa. A 28 amino acid long N-terminal sequence was established and a first series of comparisons with other transferrins was performed.
McClure JM.This article provides an overview of general health care management procedures commonly dealt with by racetrack practitioners. Although some of the conditions discussed are similar to those observed in a non-racetrack practice, the manner in which they are approached usually varies because of the unique circumstances encountered in the racetrack setting.
Oikawa M, Kaneko M, Yoshikawa T.To elucidate the pathomorphogenesis of extremely shortened small-intestinal villi, occurring spontaneously in neonatal foals, the morphology of the small intestine with stunted villi was studied in eight cases. All intestinal wall elements and the villi were poorly developed. Most villi were found to be extremely short throughout the entire length of the small intestine. The villous core consisted of undifferentiated, fibroblast-like cells held loosely together by ground substance which was rich in glycosaminoglycan. Development of the villous lamina propria was poor with respect to capillarie...
Laan TT, Spoorenberg JF, van der Kolk JH.Intake of Rumex, a plant genus of the Polygonaceae family, probably led through the assimilation of oxalic acid, to hypocalcaemia in a four-week old foal. This foal was presented with muscle rigidity and a stiff gait. Both the total and ionized calcium concentrations were low, 1.38 mmol/l and 0.54 mmol/l respectively. The foal was treated with a total of 150 ml of a 20% calcium solution IV. The foals neuromuscular signs resolved within a few hours after receiving calcium solution.
Argenzio RA, Hintz HF.Factors affecting glucose tolerance and the effect of volatile fatty acids on plasma glucose were studied with five ponies in two 5×5 latin square trials. The treatments were equimolar infusions of glucose, acetate, propionate, butyrate and isontonic saline in fed or fasted ponies.
Animals fasted for 72 hr. exhibited a markedly lower glucose tolerance than those fed ad libitum. Propionate appeared to be the only VFA stimulating a significant glucose response in the fasted animals, but no response was noted in the fed animals. The data suggest that length of fast is an important variable in...
Drews B, Milojevic V, Robles M, Wimel L, Dubois C, Rudolf Vegas A, Giller K, Chavatte-Palmer P, Daniel H, Giesbertz P, Bruckmaier RM, Ulbrich SE.Female mammalian reproductive functions are closely linked to body condition and metabolic status. Energy homeostasis is regulated by endocrine hormones such as insulin, IGF-I, leptin, and adiponectin via the hypothalamic-pituitary-adrenal axis. These metabolic hormones and their receptors are also expressed in reproductive tissues and the embryo. We investigated the relationship between circulating leptin and the fatty acid (FA) and amino acid (AA) composition of the equine uterine fluid (UF) and peripheral blood plasma (BP) by using a mass spectrometry-based approach. UF and BP were collecte...
Clayton HM, Duncan JL, Dargie JD.The mechanisms involved in the pathophysiological disturbances associated with the presence of mature Parascaris equorum in the small intestine were investigated with radioisotopic techniques. The results suggested that, compared with worm-free controls, infected foals had a reduction in gut motility, an increase in the body solids ratio, a lowering of the body pool of albumin and a decreased ability to incorporate dietary methionine into plasma protein.
Foster CV, Harris RC, Pouret EJ.After an oral dose of 10 g of L-carnitine the plasma concentrations of free and total carnitine increased in five yearling thoroughbred horses, reaching a peak two to four hours after administration, but in two horses there was no increase. In the five which responded, the mean (+/- sd) peak increase in total carnitine concentration was 15.1 +/- 6.9 mumol/litre from a predose mean of 18.8 +/- 3.4 mumol/litre, and the mean peak increase in free carnitine concentration was 13.5 +/- 3.1 mumol/litre from a pre-dose mean concentration of 12.5 +/- 2.2 mumol/litre. These changes were similar to those...
Henneman K.Addressing poor performance issues in horses is a common yet challenging request to veterinarians. Often, there are limited field diagnostic or therapy choices. Growing lay popularity in integrative therapies, as well as increasing clinical incorporation, is creating more awareness of their clinical applications. Many modalities are showing increasing evidence of positive outcomes with minimal harm, but additional safety and efficacy evaluation is needed. Integrative modalities have unique ways of perceiving disease patterns that are different from more modern approaches, and these different p...
