Exercise places an increased demand on the body's systems, both to provide fuel for working musculature and to neutralize and dispose of toxic build-up. By-products of demanding performance are reactive free radicals. Dietary consumption of vitamin E, an antioxidant, may be a plausible way to reduce free radical damage. The present study examined the effects of supplemental dietary vitamin E on the presence of oxidation products and antioxidant capacity in blood and tissue of exercising horses. Eight Thoroughbred horses were used in a crossover design study, with one group consuming a diet containing vitamin E at the 1989 National Research Council (NRC) level recommended for horses in moderate to intense work (80 IU kgDM(-1) [National Research Council (1989). Nutrient Requirements of Horses. 5th revised edn.; Washingto, DC: National Academy Press, pp. 48]), and the second group being fed the control diet plus 3000 IU day(-1) DL-alpha-tocopheryl acetate. The horses underwent an adaptation phase, an 8-week training programme and a final standard exercise test (SET) during which the horses ran on a 6 degrees incline to exhaustion, and then a washout phase. Horses were then crossed over to opposite treatment groups and these phases repeated. Blood samples were collected at specific points before and after exercise during the training period and before and after performing the SET. Neither plasma vitamin E nor thiobarbituric acid-reactive substance concentrations were influenced by supplemental vitamin E. Blood Troloxequivalent antioxidant capacity values increased (P < 0.05) following 5 weeks of training in both groups, indicating improved antioxidant capacity as horses became fitter. Vitamin E supplementation did not alter plasma reduced, oxidized or total glutathione levels, nor the percentage of glutathione in the reduced form during the training period. However, vitamin E did cause an elevation in the percentage of glutathione existing in the reduced form following a SET as compared with the control diet (P < 0.006). This is possibly due to lower plasma oxidized glutathione levels in vitamin E-treated horses (P < 0.03). This study indicates that vitamin E supplementation above NRC levels can influence certain measures of oxidative stress in intensely exercising horses, and training has the ability to improve the antioxidant status of the animal.

Intense exercise has been associated with free radical damage that forms potentially measurable by-products in the blood and muscle of exercising subjects. The extent of damage to the exercising animal has yet to be conclusively determined, and studies often focus on by-products in the blood rather than muscle. The current study examined the presence of oxidative products in the muscle of exercising horses as well as the effects of excess vitamin E on the presence of these products. Eight Thoroughbred horses were used in a crossover design, with one group being fed vitamin E at the 1989 NRC [National Research Council (1989) Nutrient Requirements of Horses. 5th revised edn.; Washington DC: National Academy Press, pp. 48] level recommended for horses in moderate to intense work (80 IUkgDM(-1)), and the second group being fed the control diet plus 3000 IU day(-1) DL-alpha-tocopheryl acetate. The horses underwent an 8-week training programme and a final standard exercise test (SET). During the SET, the horses ran on a 6 degrees incline to exhaustion. Muscle samples were biopsied before and after performing the SET and analysed for the presence of carbonyl groups and ubiquitin. Blood was collected prior to the SET and analysed for vitamin E. No significant differences in plasma vitamin E were found between treatment groups. However, myofibril carbonylation, a product of free radical damage to muscle tissue, was found to be lower in vitamin E-supplemented horses post-SET exercise (P < 0.05), suggesting that vitamin E influences some measures of oxidative stress in exercising horses, particularly following a strenuous bout of exercise. Ubiquitin was not detected in myofibrils, indicating clearance of carbonyl groups by a different mechanism.

OBJECTIVE:To evaluate the effect of ingestion of a high-carbohydrate versus a high-fat meal on relaxation of the proximal portion of the stomach and subsequent gastric emptying in horses.ANIMALS:6 healthy adult horses.PROCEDURE:The study consisted of 2 phases. In phase I, horses were offered a high-fat (8% fat) or a high-carbohydrate (3% fat) pelleted meal (0.5 g/kg) of identical volume, caloric density, and protein content. In phase II, meals consisted of a commercial sweet feed meal (0.5 g/kg) or this meal supplemented with corn oil (12.3% fat) or an isocaloric amount of glucose (2.9% fat). Proximal gastric tone was measured by variations in volume of an intragastric bag introduced through a gastric cannula and maintained with a constant internal pressure by an electronic barostat. Rate of gastric emptying was measured simultaneously with the 13C-octanoic acid breath test. Interaction between both techniques was studied in additional experiments.RESULTS:Meals with higher carbohydrate content induced a significantly more prolonged receptive relaxation of the proximal portion of the stomach than those with higher fat content, but the accommodation response was similar. Labeling the meals with the breath test marker influenced the accommodation response measured by the barostat. Gastric emptying rates were not significantly different between meals, although those high in carbohydrate initially emptied more slowly.CONCLUSIONS AND CLINICAL RELEVANCE:In horses, in contrast to most species, dietary fat supplementation may not have a profound effect on gastric motility.

91 Kirchgessner, M., Munz, W. & OeIscWiger, W. (1960) . Arch. Tierwnuhr. 10, I . Marston, H. R. (1970). B7.J Nzitr. zq, 615. Mills, C. F. (editor) (1970). Trace Element Metabolism in Animals. Edinburgh: Livingstone. Mills, C . F., Dalgarno, A. C., Williams, R. B. & Quarterman, J. (1967) . BY.?. Nutr. 21, 7 5 1 . National Research Council (1960) . Publs natn. Res. Coun., Wush. no. 827. National Research Council (1964) . Publs natn. Res. Cozm., Wash. no. I 192. National Research Council (1966) . Publs natn. Res. Coun., Wash. no. 1349. National Research Council ( 1 9 6 8 ~ ) . Publs natn. Res. Coun., Wash. no. 1694. National Research Council (1968b). Publs natn. Res. Coun., Wash. no. 1693. National Research Council (1970). Publs natn. Res. Coun., Wush. no. 1137, 4th ed. Oberleas, D. & Prasad, A. S. (1970). In Truce Element Metabolism in Animals p. 170 [C. F. Mills, editor]. Edinburgh: Livingstone. Ott, E. A,, Smith, W. H., Stob, M., Parker, H. E., Harrington, R. B. & Beeson, W. M. (1965) . J. Nutr.

Forty-four weanling horses were used in two experiments to evaluate the effect of starch intake on growth and skeletal development. In Exp. 1, the weanlings were fed either a grain-based, high-starch (31.1%, DM basis) concentrate or a by-product-based, low-starch (0.0%) concentrate with coastal bermuda-grass (Cynodon dactylon) hay. Corn oil was used to equalize the energy concentration of the concentrates. The concentrate:hay ratio was 64:36 (as-fed basis), and intake was the same for both diets. Body weight gains were greater by the weanlings consuming the high-starch concentrate (0.81 vs. 0.67 kg/d; P = 0.01). Total body length gain also was greater for the weanlings consuming the high-starch concentrate (15.5 vs. 13.2 cm; P = 0.045). Other body measurements and bone mineral deposition were not influenced by diet or gender. At the end of the experiment, postprandial blood glucose concentrations suggested that the horses on the low-starch diet were less efficient in metabolizing blood glucose than were those that had been consuming the high-starch diets. In Exp. 2, the weanlings were fed either a high-starch (34.7%) or medium-starch (17.0%) concentrate plus coastal bermuda-grass hay. Corn oil again was used to equalize the energy content of the medium-starch concentrate to that of the high-starch concentrate. The concentrate:hay ratio was 64:36 (as-fed basis), and the intake was the same for both diets. The diets did not influence rate of gain (0.75 kg/d; P = 0.98), body measurements (P = 0.11 to 0.93), or bone mineral deposition (P = 0.66). Animals on the medium-starch diet tended to have blood glucose concentrations that peaked earlier and were lower at later times than those consuming the high-starch concentrate. Bone osteochondrotic lesions were not related to the diet and were found to decrease during the course of the experiment for both the high-starch and the medium-starch diets (P = 0.006 and 0.016, respectively).

In coping with the effects of high temperatures, the movement of performance horses from temperate to tropical and sub-tropical regions places major demands on their animals metabolic and cooling systems. Without acclimation, high temperatures increase body core temperature, sweating, metabolic rate, and alter the rate at which glucose and lipids are metabolized. These effects appear to be transitory, as the animal's metabolism returns to near temperate metabolism after 2–3 weeks of acclimatization. High temperatures also result in reduced feed intake. Feeding animals under high temperature conditions generally means keeping forage intake to a minimum and maximizing the energy density of the concentrate. A high fat concentrate is recommended because fat reduces the heat load on the animal, even though the fat may be metabolically less important than glucose. Increased sweat production will increase nitrogen loss, making additional protein intake necessary. Nevertheless, protein intake, above the animal's requirement, may have an adverse effect on body heat production. Therefore, minimizing protein intake, by the addition of appropriate amino acids, such as lysine and threonine, to the diet, may be beneficial.

The objective of this study was to investigate the effects of ribose supplementation on blood ammonia-N, plasma lactic acid, plasma glucose, volume of oxygen consumption (VO2), heart rate, and performance in Thoroughbred geldings performing a maximal treadmill standardized exercise test (SET). The hypothesis tested was that ribose supplementation would decrease ammonia-N and lactic acid accumulation during exercise, and improve performance. Eight Thoroughbred geldings were assigned randomly to one of two groups: glucose or ribose. The glucose group received 0.15 g glucose/kg of BW, and the ribose group received 0.15 g of ribose/kg BW top-dressed on the feed twice daily. After 2 wk of glucose or ribose supplementation, a SET was performed. Blood was analyzed for blood ammonia-N, plasma lactic acid, and plasma glucose before exercise (0 min), every minute during SET, and at 15 and 30 min after exercise. Heart rate and VO2 were recorded for the duration of SET. After a 10-d washout period, geldings switched groups. Following another 2 wk of supplementation, a second SET was performed, and same data recorded. Blood ammonia-N and plasma lactic acid increased as duration of SET increased and reached a peak at 15 min after exercise. Peak plasma glucose was observed at 15 min after exercise, and peak heart rate and VO2 were recorded at highest speed during SET. Geldings supplemented with ribose had blood ammonia-N, plasma lactic acid, plasma glucose, VO2, heart rate, and performance similar to those of geldings supplemented with glucose. Results from this study show that supplementation with 0.15 g ribose/kg BW twice daily in the diet of conditioned Thoroughbred geldings for 2 wk does not influence blood ammonia-N, plasma lactic acid, plasma glucose, VO2, heart rate, or performance during SET or the first 30 min of recovery.

Growth rates of thoroughbred horses are not as well defined as those of other farm animals, and only a few articles summarize growth of thoroughbred horses over a prolonged period. Body weight (BW), heart girth (HG), wither height (WH), body length (BL), and hip height (HH) of 128 thoroughbred horses (59 colts and 69 fillies) were recorded from birth to 15 months of age at 14- or 28-day intervals. Data were obtained from consecutive 20 foal crops. At birth (0 day), BW was 53.55+/-5.20 kg (range. 39.04-67.19), HG was 0.82+/-0.03 m (range, 0.75-0.90), WH was 1.02+/-0.03 m (range, 0.93-1.10), BL was 0.74+/-0.03 m (range, 0.67-0.82), and HH was 1.05+/-0.03 m (range, 0.93-1.14). At weaning (112+/-3 days), BW was 1 99.57+/-13.58 kg (range, 163.44-234.26) HG was 1.29+/-0.04 m (range, 1.19-1.37), WH was 1.27+/-0.03 m (range, 1.21-1.35), BL was 1.17+/-0.03 m (range. 1.08-1.30), and HH was 1.32+/-0.03 m (range, 1.24-1.39). At 6 months (181+/-4 days), BW was 237.16+/-18.48 kg (range, 186.14-288.74), HG was 1.36+/-0.04 m (range, 1.24-1.45), WH was 1.33+/-0.03 m (range, 1.26-1.40), BL was 1.25+/-0.03 m (range, 1.17-1.33), and HH was 1.38+/-0.03 m (range, 1.28-1.44). At 12 months (361+/-8 days), BW was 337.73+/-26.61 kg (range. 267.86-394.98), HG was 1.56+/-0.05 m (range, 1.41-1.66) WH was 1.45+/-0.03 m (range, 1.36-1.55), BL was 1.42+/-0.04 m (range, 1.31-1.51), and HH was 1.49+/-0.03 m (range, 1.41-1.57). At 15 months (447+/-8 days), BW was 392.48+/-30.61 kg (range, 317.80-457.18) HG was 1.64+/-0.05 m (range, 1.52-1.76), WH was 1.49+/-0.03 m (range, 1.42-1.58), BL was 1.48+/-0.04 m (range, 1.40-1.59), and HH was 1.53+/-0.03 m (range, 1.46-1.62). Two regression equations (y(1) from birth to 112 days of age and y(2) from 113 to 450 days of age) were calculated. WTkg is estimated by y(1)=1.28x+57.82 (R-2=0.94) and y(2)=0.57x+133.28 (R-2=0.86). HG(m) is estimated by y(1)=0.0041x+0.86 (R-2=0.90) and y(2)=0.0011x+1.16 (R-2=0.84). WHm is estimated by y(1)=0.0022x+1.03 (R-2=0.85) and y(2)=0.0006x+1.22 (R-2=0.80). BLm is estimated by y(1)=0.0038x+0.77(R-2=0.92) and y(2)=0.0009x+1.09 (R-2=0.85). HHm is estimated by y(1)=0.0024x+1.07 (R-2=0.87) and y(2)=0.0006x+1.27 (R-2=0.78).

Serum bone specific alkaline phosphatase (BALP) and osteocalcin were measured in 9 Thoroughbred and 4 Quarter Horse (QH) foals. Eight were colts, and 5 were fillies. The first blood sample was collected from foals between 10 and 14 hours after birth on day 1. Blood then was collected on days 3, 6, 9, 12, 15, 18, 21, 28, 35, 42, 49, 56, 70, 84, 98, and 112 between 7:00 and 9:00 AM. Serum bone metabolism marker raw data were analyzed with analysis of variance with repeated measures over time with gender and breed in the model. Average serum osteocalcin concentrations were higher for Thoroughbred than QH foals: 152.1 +/- 4.6 ng/mL and 131.3 +/- 6.3 ng/mL (mean standard error), respectively (P = .01). No overall differences were seen for gender (P = .10). However, on day 1, colts had higher osteocalcin than did fillies at 199.6 +/- 30.2 ng/mL and 93.8 +/- 32.4 ng/mL, respectively (P = .04). Thoroughbred foals had higher average serum BALP concentrations than did QH foals, with average values of 260.8 +/- 13.4 U/L and 205.1 +/- 18.5 U/L, respectively (P = .02). No gender differences were seen for serum BALP (P = .48). Serum carboxyterminal propeptide of Type I procollagen (PICP) concentrations could not be measured in this study because the Metra Biosystems assay for PICP could not be validated.

Two experiments were conducted with yearling horses to determine whether the use of a concentrate designed to be fed with Coastal bermudagrass hay would cause growth differences or skeletal abnormalities when fed with western alfalfa hay. In experiment 1, 13 thoroughbred and quarterhorse yearlings, 332.8 ± 8.5 days, of age were assigned at random within breed and gender subgroups to 1 of 2 diets: (1) alfalfa hay plus a 12.7% CP concentrate and (2) coastal bermudagrass hay plus the same concentrate. The horses were housed in drylot paddocks in groups of 3 or 4 animals and group fed the hay at 1 kg/100 kg BW daily. The concentrates were fed individually to appetite for two 1.5-hour feeding periods daily for 112 days. Orts were weighed back daily. The animals were weighed, measured, and blood samples collected at the start of the experiment and at 28-day intervals for 112 days. Radiographs of the third metacarpal were made on day 0, 56, and 112 for estimation of bone mineral content. In experiment 2, 15 thoroughbred and quarterhorse yearlings, 345.6 ± 8.4 days of age, were used to repeat the experiment. The concentrate fed in this experiment contained 12.4% CP. In experiment 1, the hay protein content was less than anticipated, resulting in a protein intake below NRC1 recommendations. In experiment 2, the hay protein was higher and more typical of NRC1 values. In both experiments, feed intake of the 2 diets was not different (P > .10). Weight gain (P = .0136, P = .0330), heart girth gain (P = .0084, P= .0044), and hip height gain (P = .0165, P = .0137) were higher for the alfalfa fed yearlings for experiment 1 and experiment 2, respectively. Withers height gain (P = .0079) and body length gain (P = .0232) were also greater for the alfalfa fed yearlings on experiment 2. Bone mineral content and bone metabolism indicators were not influenced by diet (P > .10).

A diverse group of studies, which are equine exclusive, indicate that ribose administered to myocardial and skeletal muscle tissue stimulates ATP production and recovery. This study investigated the effects of ribose supplementation on blood and muscle metabolites and performance in Thoroughbred geldings performing a maximal treadmill standardised exercise test (SET). In Experiment 1, 6 conditioned Thoroughbred geldings performed a baseline SET and horses were assigned to one of 2 experimental treatment groups, placebo or ribose, based on VO2max. The placebo treatment group received 0.07 g glucose/kg bodyweight (bwt) and ribose treatment group received 0.07 g ribose/kg bwt top dressed on the feed twice daily. Following a 2 week treatment period, a second SET was performed. After a one-week washout period, the horses switched treatment groups. Following another 2 week treatment period, a third SET was performed. Blood ammonia-N was lower in the ribose treatment group at 15 min (P = 0.06) and 30 min (P = 0.02) postexercise. Plasma lactic acid was lower in the ribose treatment group at 30 min postexercise (P = 0.07). In Experiment 2, 1 h before a SET, 2 horses received 3 l water (control) and 3 horses 250 g of ribose dissolved in 3 l water (single ribose dose) via a nasogastric tube. Following a 2 week washout period, the horses switched treatment groups and another SET was performed. There were no differences in blood ammonia-N, plasma lactic acid or glucose between treatment groups. No differences in performance were detected between treatment groups in either experiment. In conclusion, the results from Experiment 1 show a trend that daily ribose supplementation may be beneficial during recovery from exercise. However, a single dose of ribose 1 h before exercise revealed no effect on the variables measured. Because moderate to intense daily exercise can cause a decrease in total adenine nucleotide (TAN) pool with no meaningful recovery even after 72 h rest, future experiments should be designed to futher elucidate the effects of ribose supplementation on TAN metabolism in horses exercising at high intensity.

Soybean hulls have been used as a feed ingredient for horses for many years and are generally used as a fiber source. The NRC (11) gives them an energy value of 1.88 Mcal DE/kg DM, which is comparable with a medium quality grass hay. Recent evidence suggests that soybean hulls may have a higher energy value. Two feeding trials were conducted to evaluate the energy value of soybean hulls by using them to replace oats in a concentrate for weanling horses. In Exp. 1, 16 Thoroughbred and Quarter Horse weanlings, 145.2 4.1 d of age, were paired within breed and gender subgroups and assigned at random to either the oats or soybean hull-based concentrate. Soybean hulls replaced oats at 25% of the concentrate. Concentrates were fed individually to appetite for two, 1.5-h feeding periods daily with the concentrate restricted to the lesser amount consumed by the pair based on percentage of BW. Coastal bermudagrass (Cynodon dactylon) hay (12.8% CP) was group fed at 1.0 kg/100 kg BW daily. The BW and measurements of the weanlings were made at 14-d intervals for 112 d, and the weanlings were radiographed for bone mineral deposition determinations at the start and conclusion of the study. Experiment 2 used 13 weanlings starting at 143.8 ± 4.2 d of age and was identical to Exp. 1 except the source of the Coastal bermudagrass hay was different and the concentrate intake was fed ad libitum during the two, 1.5-h feeding periods. In Exp. 1, no differences in feed or nutrient intake, BW, or body measurement gains were detected (P > 0.05) except for body length gain, which was greater for the weanlings on the oat-based concentrate (P < 0.05). The weanlings gained 0.73 and 0.70 kg/d on the oat and soybean hull-based concentrates, respectively. In Exp. 2, the protein content of the hay (7.0% CP) was less than the previous year, resulting in a protein intake below NRC (11) recommendations. No differences in BW, withers height, or body length gain were detected (P < 0.05), but heart girth (P < 0.05) and hip height gain (P < 0.05) were both greater for the weanlings fed the oat-based concentrate. The weanlings gained 0.74 and 0.61 kg/d on the oat and soybean hull-based concentrates, respectively. Bone mineral deposition was not different between diet groups for either experiment. Results suggest that soybean hulls have an energy value for weanling horses that is similar to oats when fed with medium quality grass hay. When fed with low quality grass hay, soybean hulls do not seem to be as valuable as oats, perhaps because of either the slow energy release or the availability of protein in the foregut.

Forty-four Thoroughbred and Quarter Horse weanlings were used in three experiments to evaluate the effects of energy content, protein content, and feeding levels of the concentrate on growth and development when fed with Coastal bermudagrass hay. The animals were confined to drylot paddocks and fed the assigned concentrate in individual feeding stalls. The hay was group-fed in the paddocks. In the first experiment, the concentrate was fed at 1.5 kg/100 kg BW daily or ad libitum for two 1.5-h feeding periods daily. The ad libitum-fed weanlings had greater withers height gain (P<0.01), and hip height gain (P<0.05) than the limit-fed weanlings. Bone mineral gains were numerically greater for the ad libitum-fed weanlings (P>0.10). None of the other body measurements were different (P>0.05). In Exp. 2, weanlings were fed a basal concentrate ad libitum for two1.5-h feeding periods daily or a fat-added concentrate at equal amounts to the hay intake. Nutrients were balanced to meet NRC recommendations. The fat-added concentrate resulted in numerically greater withers height (P>0.10), heart girth (P>0.10), body length (P>0.10), hip height (P>0.10), and bone mineral (P>0.10) gains. Weight gain and feed efficiency favored the basal diet. In Exp. 3, weanlings were fed concentrates providing either 14 or 18% CP as described previously. The BW gains favored the high protein diets for three of the first four periods (P<0.05), and some numerical advantage persisted to the end of the trial (P>0.10). None of the other growth measurements were different for the two diets. Calculations on nutrient intake and BW gains of the animals on the three experiments revealed that lysine intake appears to be a greater factor than energy or protein in influencing BW gain of weanlings.

Fifteen yearlings, nine Thoroughbreds and six Quarter Horses, were used in a feeding trial to determine whether proteinated trace minerals were utilized advantageously over inorganic trace minerals for growth and development when included in the diet at normal supplementation levels. The animals were assigned randomly within breed and gender subgroups to one of two treatments. Group A received a 12% protein (as fed) concentrate containing a trace mineral premix providing inorganic trace minerals at concentrations appropriate to supplement Coastal Bermuda grass (Cynodon dactylon) hay and provide NRC1 or higher trace mineral intakes. Group B was provided the same concentrations of trace minerals but the Cu, Mn, and Zn were provided via a commercial proteinate. The concentrates were fed to appetite individually, twice daily during a 1.5-hour feeding period. The hay was group-fed in drylot paddocks at 1.0 kg/100 kg BW daily. The animals were housed three or four animals per paddock. Weight and body and hoof growth measurements were taken at the start of the experiment and at 28-day intervals for 112 days. Radiographs of the third metacarpal were made for estimating bone mineral and hoof samples were collected at the start and completion of the experiment. The yearlings gained 0.77±0.03 and 0.79±0.03 kg/d for the inorganic and proteinate groups, respectively. None of the body measurements were affected by diet (P > 0.10) except hip height gain which was higher for the animals receiving the proteinated minerals (7.0 vs 4.7 cm, P = 0.023). Hoof growth was greater for yearlings fed the mineral proteinate than for those fed the inorganic minerals (4.98 vs 4.78 cm, P = 0.016), and colts had greater hoof growth than did fillies (5.00 vs 4.72 cm, P = 0.003). Diet and gender did not affect hoof strength (P > 0.10), but Quarter Horses had greater hoof strength than Thoroughbreds (98.2 vs 88.8 kg, P = 0.046). No differences in bone mineral content or bone mineral deposition were detected (P > 0.10).

Electro-acupuncture (EA) treatments varied in their effect on pain threshold in horses. EA stimulation using local acupuncture points or/and high frequency (80–120 Hz) can be more effective to relieve the experimental pain than the use of distal points and/or low frequency (20 Hz). The acupoints close to the painful areas may need to be stimulated with high frequency EA while the acupoints far from the painful areas may be stimulated with low frequency EA. The release of β-endorphin may be one of the pathways in which electro-acupuncture relieves the experimental pain.

Thoroughbred and Quarter Horse yearlings (n = 24; 335+/-7 d of age) were used in a 112-d feeding trial to determine whether chromium (Cr) supplementation would alter growth, development, and energy metabolism of growing horses on high-concentrate diets. The horses were assigned at random within breed and gender subgroups to one of four treatment groups: A) basal concentrate; B) basal plus 175 microg of Cr/kg concentrate; C) basal plus 350 microg of Cr/kg concentrate; and D) basal plus 700 microg of Cr/kg concentrate. Chromium was provided via Cr tripicolinate (Prince Agri Products, Quincy, IL). The horses were weighed, measured for withers and hip height, heart girth, and body length and underwent ultrasound evaluation for croup fat thickness. The concentrate was fed for ad libitum consumption for two, 1.5-hr feeding periods daily. Coastal bermudagrass (Cynodon dactylon) hay was group-fed (six animals/group) at 1% of BW daily. Feed intake was 60% concentrate and 40% hay, resulting in a supplemental Cr intake of 0, 105, 210, and 420 microg/kg diet for groups A, B, C, and D, respectively. Colts consumed more concentrate and total feed than did fillies (P < .05), but no dietary effect on feed intake was detected. Colts weighed more than fillies at the completion of the experiment (P = .0754), but no dietary effects on weight, body measurements, or croup fat were detected. An i.v. glucose tolerance test (.2 g of glucose/kg BW) and an i.v. insulin sensitivity test (.1 IU of insulin/kg BW) were conducted on each animal during the third 28-d period of the experiment. Plasma glucose peaked immediately following injection and decreased more rapidly in animals consuming the high-Cr diet than in those consuming the control diet (P < .01). Mean glucose fractional turnover rate values increased (P = .0369) and mean half-life of glucose decreased (P = .0634) in response to the high Cr supplementation. Plasma glucose depletions in animals fed the other two diets were between and not different from (P > .10) the depletions in control animals or in those fed high-Cr diets. No difference in insulin sensitivity was detected (P > .10). Results indicate that Cr tripicolinate supplementation of yearling horses increases the rate at which glucose is metabolized and may lower the plasma glucose concentration. No effect of Cr supplementation on development of the animals was detected.

Eighteen mares were used in a 92-day feeding trial to evaluate a complete, extruded feed for free choice feeding horses. The mares were assigned at random to one of three treatments as follows: Group A—Control—bahiagrass pasture+complete mineral free choice; Group B—Dry lot —Extruded feed + salt free choice; Group C—Stalled—Extruded feed + salt free choice. The pastured mares were on pasture 24 hours per day and had access to a complete mineral in a fiberglass mineral feeder. The mares fed in dry lot were fed only the extruded feed and salt, both of which were available to them 24 hours per day. The stalled mares were provided access to the extruded feed and salt for 22 hours per day. The other two hours they were turned out into a dry lot paddock for exercise. Fecal samples were collected from each of the mares on the extruded feed for estimation of feed digestibility. The pastured mares gained weight on pasture but lost girth, croup fat and condition score. Feed consumption by the dry lot fed mares peaked at three weeks at about 15.9 kg/animal/d and remained constant for the remainder of the trial. Feed consumption by the stalled mares peaked at 19.1 kg/animal/d but decreased to about 15.9 kg/animal/d during the second month and remained constant for the duration of the trial. Most of the stalled mares experienced some edema of the lower extremities which decreased during the last month of the experiment, probably due to increased activity when they were turned out. One of the stalled mares experienced multiple episodes of colic and was removed from the experiment. At the time of removal, the animal was consuming 22.7 kg of the extruded feed daily. The mares consuming the extruded diet gained more weight, heart girth, croup fat and condition score (P<0.05) than the pastured horses. The mares kept in stalls gained more weight and condition score than the mares fed in dry lot (P <0.05). Average daily mineral intake by groups A, B, and C were 80.2.4.7, and 11.4 g/d, respectively. Digestibilities by the two groups receiving the extruded feed were not different.

Equine acute diarrhea is a common clinical problem. Six types of acute diarrhea in horses will be described in detail in term of symptoms, diagnosis and herbal treatments in this paper. Twenty-one herbal formulas for treatment of different types of diarrhea will be introduced. Clinical results of each herbal formula will be evaluated.