Carey A. Williams

Inflammatory and redox status of ponies with a history of pasture-associated laminitis

Inflammatory and redox signals could render lamellar tissue susceptible to damage and contribute to higher risk for laminitis in obese or insulin resistant ponies just as these factors contribute to health risks in humans with metabolic syndrome. This study evaluated circulating markers of inflammatory and redox status in ponies that had a history of recurrent bouts of pasture-associated laminitis (PL, n = 42) or had never developed clinical laminitis (NL, n = 34) under the current management conditions. There were no differences (P > 0.05) between PL and NL ponies for markers of antioxidant function (glutathione, glutathione peroxidase, superoxide dismutase) or increased oxidative pressure (malondialdehyde, apoptosis, 3-nitrotyrosine). Inflammatory status, as indicated by fibrinogen concentration, was also not different between pony groups (P = 0.84). However, PL ponies had higher (P < 0.001) plasma concentrations of the pro-inflammatory cytokine TNF-alpha than NL ponies. This suggests that a predisposition to laminitis is associated with increased circulating inflammatory cytokines. TNF-alpha could also represent a contributing factor to increased insulin resistance observed in laminitis prone ponies. These results provide new insight into potential mechanisms and risk factors underlying laminitis.

Nutritional supplementation, performance, and oxidative stress in college soccer players.

Arent, SM, Pellegrino, JK, Williams, CA, DiFabio, DA, and Greenwood, JC. Nutritional supplementation, performance, and oxidative stress in college soccer players. J Strength Cond Res 24(4): 1117-1124, 2010-The purpose of this study was to examine changes in performance and metabolic parameters in collegiate soccer players during preseason preparation and to determine the impact of a nutraceutical blend proposed to reduce oxidative stress. Male Division I college soccer players (n = 22) performed a progressive maximal treadmill test at the beginning and end of preseason to assess changes in &OV0312;o2max, velocity at lactate threshold (VLT), time-to-exhaustion, lipid hydroperoxide (LPO), 8-isoprostane, and creatine kinase (CK) response. After baseline testing, athletes were randomly assigned to receive the nutraceutical blend (EXP; n = 12) or an isocaloric equivalent (CON; n = 10) for 20 days of preseason training. Δ&OV0312;o2max (2.1 ± 3.3 ml·kg−1·min−1, p = 0.007), ΔVLT (0.8 ± 1.4 km·h−1, p = 0.045), and Δtime-to-exhaustion (39.4 ± 77.4 seconds, p = 0.033) were improved across groups, but a significant effect of supplementation on performance was not seen. Changes in resting levels of CK from the beginning to end of preseason were significantly lower (p = 0.044) in EXP (64.8 ± 188.4 U·L−1) than in CON (292.8 ± 304.8 U·L−1). Additionally, EXP demonstrated a significant decrease in the magnitude of the 8-isoprostane response at Trial 2 compared with Trial 1 (effect size [ES] = −0.74), whereas CON had an increased response (ES = 0.20). A similar pattern was seen for LPO (p = 0.067). Preseason training in male college soccer players resulted in significant improvements in &OV0312;o2max, VLT, and time-to-exhaustion. Supplementing with a proprietary antioxidant and nutraceutical blend may enhance some of these effects as indicated by magnitude of the responses. However, it appears that the most notable effects of supplementation were seen for reduced CK and oxidative stress, at least with short-term supplementation.

Biomarkers of Antioxidant Status, Inflammation, and Cartilage Metabolism Are Affected by Acute Intense Exercise but Not Superoxide Dismutase Supplementation in Horses

Objectives were to evaluate effects of (1) repetitive arthrocentesis on biomarkers of inflammation (prostaglandin E2, PGE2) and aggrecan synthesis (chondroitin sulfate-846; CS) in synovial fluid (SF); (2) exercise and superoxide dismutase (SOD) supplementation on biomarkers of inflammation, antioxidant status, and aggrecan synthesis, in horses. Preliminary trial. Standardbreds underwent four arthrocentesis procedures within 48 h and exhibited elevated CS and no changes in PGE2. Exercise trial. this randomized crossover design used twelve Standardbred mares which received either treatment (3000 IU d−1 oral SOD powder) or placebo (cellulose powder) for 6 wks which culminated with them running a repeated sprint exercise test (RSET). Samples were collected before (PRE), during (PEAK), and following exercise (POST). Exercise resulted in increased (P < 0.05) antioxidant defenses including erythrocyte SOD, total glutathione, glutathione peroxidase, gene transcripts for interferon-gamma, interleukin-10, and interleukin-1β in blood, and decreased plasma nitric oxide. Exercise increased (P < 0.05) SF CS and adjusted-PGE2, and higher (P < 0.05) CS and PGE2 were found in hock versus carpus joints. No treatment effects were detected. Results suggest normal adaptive responses likely due to exercise-induced tissue microdamage and oxidative stress. Additional research is needed to identify benefit(s) of SOD supplementation in horses.

Lipoic Acid as an Antioxidant in Mature Thoroughbred Geldings: A Preliminary Study

alpha-Lipoic acid (LA) has demonstrated antioxidant effects in humans and laboratory animals. The objective of this study was to determine whether the effects of LA are similar in horses. Five Thoroughbred geldings were supplemented with 10 mg/kg/d DL-alpha-lipoic acid in a molasses and sweet feed carrier and five received only the carrier as a placebo (CON). Blood samples were obtained at baseline (0 d), after 7 and 14 d of supplementation, and 48 h postsupplementation (16 d). Blood fractions of red and white blood cells (RBC and WBC, respectively) and plasma were analyzed for glutathione (GSH), glutathione peroxidase (GPx) and total plasma lipid hydroperoxides (LPO). An experienced veterinarian observed no adverse clinical effects. Plasma LPO baselines differed between groups (P = 0.002). When covariates were used, there was a decrease over time in the LA group (P = 0.015) and concentrations were lower in the LA group than in the CON group at 7 and 14 d (P = 0.022 and P = 0.0002, respectively). At baseline, GSH concentration was 69 +/- 7 in WBC and 115 +/- 13 mmol/mg protein in the RBC, with no differences resulting from either time or treatment. The GPx activity was 47 +/- 4 and 26 +/- 5 U/g protein at baseline WBC and RBC, respectively, with a lower concentration in the LA groups WBC at 7 (P = 0.019) and 14 d (P = 0.013). The results show that 10 mg/kg LA had no evident adverse effects, and moderately reduced the oxidative stress of horses allowed light activity. These findings encourage studying of LA in horses subjected to strenuous exercise.

Vitamin E intake and systemic antioxidant status in competitive endurance horses

The objective was to compare vitamin E content in the total diet of Arabian horses competing in the 80 km Research Ride 2002 to the oxidative stress and antioxidant measures throughout the race. Prior to the race, riders completed a detailed nutritional survey, which was used to calculate vitamin E intake. Blood samples, temperature and heart rate were taken the day before the race, at 27 and 48 km during the race, at race completion or elimination and 3 h after race completion. Plasma lipid hydroperoxides, α-tocopherol (TOC), creatine kinase (CK), aspartate aminotransferase (AST), albumin, red and white blood cell total glutathione and glutathione peroxidase were measured. Data were analyzed by Pearsons correlation in SAS. From the survey, it was estimated that horses consumed 2265±114 IU day −1 of vitamin E. A negative correlation was found between the vitamin E intake and CK ( r = −0.23; P = 0.002), and AST ( r = −0.22; P = 0.003). A positive correlation was found between the vitamin E intake and plasma TOC ( r = 0.15; P = 0.005) at all sample times. This suggests that intensely exercising horses supplemented with vitamin E may not have an improved welfare and performance if they are supplemented vitamin E versus what is naturally found in forages and commercial feeds.

Antioxidant status in elite three-day event horses during competition.

The objective of this study was to determine if competition intensity would have an effect on antioxidant status in horses before and during a three-day event. Body weight, body condition score, and blood was sampled from CCI2* (n = 19) and CCI3* (n = 23) horses before the start of dressage, 20 to 30 min following cross-country, and 18–24 h after cross-county. Data were analyzed using a PROC MIXED in SAS. There were no differences between CCI2* and CCI3* horses during competition for plasma cortisol, lactate, α-tocopherol, retinol, or erythrocyte glutathione peroxidase. After cross-country, CCI3* horses had higher serum creatine kinase (P = 0.003) and aspartate aminotransferase (P < 0.0001) than the CCI2* horses. Plasma β-carotene was higher in the CCI2* horses compared to the CCI3* horses (P = 0.0001). Total erythrocyte glutathione was also higher in the CCI2* horses versus CCI3* horses (P < 0.0001). These results are the first report of antioxidant status of horses competing in this level of a three-day event. The changes in antioxidant and muscle enzymes observed between divisions are likely due to the increased anaerobic and musculoskeletal demand on the upper level horses and the fitness required to compete at that level.

Antioxidant supplementation to the exercising horse

Evidence of oxidative stress in horses has been described in reports dealing with intense and endurance exercise. Oxidative stress occurs when antioxidant systems are insufficient causing oxidation to potentially damage DNA, proteins, and lipids, and contribute to degenerative changes. Vitamin E is the most commonly supplemented antioxidant in horses and has been shown that horses in exercise conditioning may require higher intakes of vitamin E than recommended. Also in various species vitamin C potentiates the effects of vitamin E; however, under maintenance conditions horses have the ability to synthesize sufficient ascorbate, the demand increases as stress on the body is increased. Competitive endurance horses were estimated to consume 1.2 to 5-times higher levels of vitamin E than recommended intakes. In these horses a negative correlation was found between the vitamin E intake and creatine kinase, and aspartate aminotransferase. Similarly, three-day event horses have vitamin E average intakes about 50% over recommended levels, and it was also found that intake of vitamin E negatively correlated with inflammatory markers. However, large doses of vitamin E at about 10-times the recommended levels could potentially interfere with beta-carotene absorption. While some studies have shown benefits of lipoic acid supplementation in endurance trained horses similar to that of vitamin E, other studies failed to show any benefit of supplemental superoxide dismutase in intensely exercising horses. The implications from this broad scope of work show potential benefits for supplementing various antioxidants however, before assuming efficacy from other species horse specific studies should be performed.

Technical note: Comparing 4 techniques for estimating desired grass species composition in horse pastures.

Many methods exist for estimating species composition, but few studies compare those useful in improved horse pastures. The objective of this study was to examine 4 techniques for estimating desirable forage species composition in 2 cool-season horse pastures based on prevalence estimates, repeatability, bias, and practicality, and to select a method for use in a subsequent grazing study. The techniques included Equine Pasture Evaluation Disc (EPED), Line-Point Intercept with 3 transects of 50 observations each (LPI 3-50), LPI with 5 transects of 30 observations each (LPI 5-30), and Step Point (StPt). A generalized linear-mixed effects model procedure of SAS (GLIMMIX) with a logit link was used to test for differences among each species separately. When methods were significantly different (α = 0.05), pairwise comparisons were performed using a paired t-test. The methods did not differ in detecting creeping bentgrass (P = 0.3334) or orchardgrass (P = 0.4207), but there were differences for Kentucky bluegrass (P = 0.0082), tall fescue (P = 0.0314), and other (P = 0.0448). Repeatability plots displayed lower method repeatability as species prevalence increased. Agreement was analyzed between pairs of methods by grass species. Five out of 30 pairs showed significant overall bias (P = 0.0114, 0.0045, 0.0170, 0.0328, and 0.0404), and 3 of them were between LPI 3-50 and EPED. The LPI 3-50 and LPI 5-30 techniques agreed perfectly in prevalence and bias, as did StPt and EPED, meaning they can be used interchangeably. The techniques LPI 3-50 and EPED were the most dissimilar methods. In conclusion, StPt can be used interchangeably with LPI, but StPt was selected due to its thorough representation of the pastures and ease of use.

A Review of Equine Grazing Research Methodologies

ABSTRACT Recently, there has been a renewed interest and an increase in published research on equine grazing and pasture management. The objectives of this paper are to review equine grazing research methodologies with an aim to encourage standardized research procedures. This review highlights standard methods used in equine pasture‐related research, including use of climate data and soil type; seed bed preparation and grazing management; determining forage nutritive value; defining forage maturity; tracking horse health parameters; evaluating different grazing systems; and future technologies. This review covers in‐depth discussions on determining forage biomass yield, forage populations, ground cover, persistence, forage intake, and grazing behavior. Specifically, mechanical harvesting, hand clipping, rising plate meter, and falling plate meter are all methods used to determine forage biomass yield. Frequency grid, point sampling, visual assessment, Natural Resources Conservation Service pasture condition score, and the double Dominant, Abundant, Frequent, Occasional, Rare (DAFOR) scale can be used to track forage populations, ground cover, and persistence of pasture species. Three primary methods have been used when estimating horse forage intake including the difference between pre‐ and postgrazing herbage mass, the difference in pre‐ and postgrazing bodyweight, and use of digestibility and fecal output markers. Equine grazing behavior has been described by investigating preference, pre‐ and post‐sward height, and bite and mastication rate. Awareness of key methodologies should encourage movement toward research protocol standardization that will allow for scientific comparisons and application of pasture‐related research results across the horse industry. HIGHLIGHTSThe objectives of this paper are to review equine grazing research methodologies.The goal is to encourage movement toward research protocol standardization.Forage yield, ground cover, persistence, intake, and behavior are discussed.Forage maturity, horse health, and different grazing systems are also discussed.

Use of Ground-Penetrating Radar to Determine Depth to Compacted Layer in Soils Under Pasture

New Jersey, like many states in the northeastern USA, has a high demand for grazing land for horses. Grazing lands are often intensively used because of the limited possibilities for crop rotation. A ground-penetrating radar (GPR) study was conducted in an area under different management with soils formed in old alluvium and fluviomarine sediments (Ultisols). In the grazing field, no significant signs of compaction were detected with GPR. In the feeding fields, compaction was significant within 24 cm soil from the soil surface. The GPR data were used to generate a contour map representing the depth to the compacted layer. It is concluded that soil compaction can be adequately mapped using GPR.