The effect of dietary fish oil supplementation on exercising horses

Antioxidant capacity and athletic condition of endurance horses undergoing nutraceutical supplementation

Endurance is an equestrian discipline that primarily relies on aerobic metabolism. Intense aerobic exercise produces reactive oxygen species due to an imbalance between oxidant and antioxidant substances, known as oxidative stress, which may reduce athletic performance. This study evaluated the effects of a feed supplement containing natural antioxidants and omega-3 fatty acids on the blood antioxidant activity and the athletic condition of endurance horses undergoing an exercise test. Twelve Arabian endurance horses were randomly assigned to treatment or control groups. At T0, blood lactate, whole blood and red blood cells (RBC) antioxidant capacity were assessed. The horses performed an exercise test with heart rate monitoring. After 30 min, blood lactate, antioxidant capacity and serum creatine kinase (CK) were measured. The treatment group received the dietary supplement for 21 days, while controls maintained their diet. Then, the protocol was repeated (T1). Variables were compared within and between groups through two-way ANOVA and post-hoc tests. Significant time*group effects were observed for serum CK (p = 0.026), RBC antioxidant capacity at rest (p = 0.034) and post-exercise (p = 0.019). At T1, in treatment group, CK was lower than controls (p = 0.006), while RBC antioxidant capacity increased at rest (p = 0.037) and after exercise (p = 0.006) compared to T0. The dietary supplement showed efficacy in enhancing RBC antioxidant capacity, and it could be beneficial for horses engaged in intense aerobic exercise.

Effect of a dietary nutraceutical "STRUCTURE-Joint" on response of horses to intra-articular challenge with IL-1: implications for tissue adaptation to stress

The purpose was to determine local (articular) and systemic effects of intra-articular interleukin-1 in horses supplemented with a dietary PUFA supplement [STRUCTURE-Joint (ST-J)]. Sixteen (16) healthy, mature, light breed horses were randomly assigned to diets containing 0 or 120 mL (n = 8 per group) of ST-J for 30 d. On days 0 (prior to beginning supplementation) and 27, recombinant equine interleukin-1β (reIL-1 β) (75 ng) was injected into the left or right intercarpal joint to induce mild, transient synovitis. Synovial fluid was obtained by aseptic arthrocentesis at postinjection hour 0 (immediately prior to IL-1 injection), 6, 12, and 72. ST-J supplementation for 30 d significantly increased synovial fluid nitric oxide, and resolvin D1 compared with the unsupplemented control group and significantly increased PGE2 levels and reduced joint circumference in the ST-J treated horses on day 30 compared to the same group of horses on day 0. There was also a significant increase in plasma hemoglobin, free and total bilirubin, and decrease in plasma glucose. These data provide evidence for the usefulness of ST-J to modulate physiological variables with importance in exercise performance and tissue adaptation to exercise stress and further research on this product is warranted.

Nutraceutical Supplement Mitigates Insulin Resistance in Horses with a History of Insulin Dysregulation During a Challenge with a High-Starch Diet

Insulin dysregulation (ID) is associated with an increased risk of laminitis which often necessitates the need for clinical intervention. To test the contention that the prophylactic supplementation of nutraceuticals could mitigate ID in susceptible horses, 16 mature horses with a history of ID were supplemented with either the placebo (n = 8) or nutraceutical (n = 8) once daily. Horses were housed in dry lots with ad libitum access to grass hay and fed a concentrate twice daily to provide 0.5 g starch/kg BW/meal. A combined glucose-insulin tolerance test was performed on all horses before and after 4 weeks of treatment. Nutraceutical-supplemented horses had 61% greater (p = 0.05) glucose clearance rates compared to the placebo group. This resulted in a shorter time in the positive phase of glucose clearance (p = 0.03) for the nutraceutical group compared to the placebo group. Horses receiving the nutraceutical had lower (p = 0.003) insulin concentrations at 75 min and lower (p = 0.04) glucose concentrations at 45 min compared to the placebo. Prophylactic supplementation with nutraceuticals resulted in greater glucose clearance rates during a starch challenge, indicating that nutraceuticals can mitigate ID in susceptible horses consuming an excess of non-structural carbohydrate.

Effects of dietary camelina, flaxseed, and canola oil supplementation on plasma fatty acid concentrations and health parameters in horses

Camelina (Camelina sativa) is a hardy, low-input oilseed crop that provides a rich source of the n-3 fatty acid, α-linolenic acid (ALA). The primary purpose of the present study was to assess the effects of dietary camelina oil (CAM) consumption on various health parameters, as compared to horses fed canola oil (OLA) or flax oil (FLX). Secondly, to determine how dietary CAM, FLX, and OLA alter circulating plasma total lipids across time. Thirty horses, from three separate herds, were used for this study [14.9 years ± 5.3 years; 544 ± 66 kg calculated BW (mean ± SD)]. After a 4-week gradual acclimation period using sunflower oil mixed with soaked hay cubes, horses were balanced by location, age, sex, weight, and breed and randomly allocated to one of three treatment oils (CAM, OLA, or FLX) at an inclusion of 370 mg of oil/kg BW/day. Horses had ad libitum access to hay and/or pasture for the duration of the study. Body condition score (BCS), BW, oil intake, complete blood counts, plasma biochemical profiles, and plasma total lipids were measured on weeks 0, 2, 4, 8, and 16 throughout the 16-week treatment period. BW, BCS, and oil intake were analyzed using an ANOVA using PROC GLIMMIX in SAS Studio. Complete blood counts and biochemical profiles were analyzed using an ANCOVA, and fatty acids were analyzed using an ANOVA in PROC MIXED in SAS Studio. No differences were observed among treatment groups for BW, BCS, oil intake, complete blood counts, and biochemical parameters. Individual fatty acids that differed among treatments and/or across time were largely reflective of the different FA profiles of the oils provided. Most notably, plasma ALA was greater for FLX than OLA, but neither differed from CAM (P = 0.01). Linoleic acid did not differ among treatments or over time (P > 0.05). The n-6:n-3 ratio decreased over time for both CAM and FLX, and ratios were lower for FLX than OLA at week 16, but not different from CAM (P = 0.02). These results suggest that dietary CAM had no adverse effects on health parameters and that daily supplementation of CAM and FLX at 370 mg of oil/kg BW/day induces positive changes (a decrease) in the n-6:n-3 status of the horse. Consequently, CAM may be considered as an alternative oil to FLX in equine diets.

Dietary Transitions Toward Sustainable Horse Feeding

Sustainability is the balancing act of optimizing the use of current resources without compromising the current or future environment. Within the agriculture sector the primary focus of sustainability has been to reduce environmental pollution, specifically greenhouse gasses (GHG) emissions, nitrogen emissions, and leaching. For the equine industry the first step towards sustainability is the documentation and critique of current feeding and management practices to permit modifications to enable the industry meet social and legislative obligations. As a monogastric hindgut fermenter on a per kg bodyweight basis the horse has relatively lower GHG emissions compared to ruminants. However, there are several opportunities to further reduce the environmental impact of the equine industry. The majority of these relate to subtle changes, or consideration of, improving feed conversion, using alternative ingredients, and management of fecal material associated with intensive husbandry. To initiate the journey towards sustainability this review documents opportunities with current equine feeding and management practices to reduce the environmental impacts of the equine industry.

Effect of dietary krill oil supplementation on horse red blood cell membrane fatty acid composition and blood parameters

Supplementation with marine-derived n-3 long-chain polyunsaturated fatty acids (LC PUFAs), eicosapentaenoic acid (EPA, 20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3) is linked to beneficial health effects in both humans and horses. Krill oil (KO), which is extracted from the Antarctic krill (Euphausia superba), is well documented as a safe and biologically available dietary supplement in humans and several animal species, but there is a lack of documentation regarding its effect as a dietary ingredient for horses. The objective of this study was to test whether KO as a dietary supplement had the ability to raise horse red blood cell (RBC) membrane EPA and DHA, expressed as the n-3 index. Five nonworking Norwegian cold-blooded trotter horse geldings (body weight [BW]: 567 ± 38 kg) were supplemented with KO (10 mL/100 kg BW) for 35 days in a longitudinal study. Blood samples were analysed for RBC membrane fatty acid (FA) profile, haematology and serum biochemistry every 7th day. KO was well accepted by all horses, and no adverse health effects were observed during the 35-day trial period. KO supplementation affected the RBC membrane FA profile by increasing the n-3 index from Day 0 to 35 (Day 0: 0.53% vs. Day 35: 4.05% of total RBC FAs). The observed increase in the sum of EPA and DHA (p < 0.001), total n-3 FAs (p < 0.001) and the reduction of n-6 FAs (p < 0.044) resulted in a lower n-6:n-3 ratio (p < 0.001) by Day 35 of KO supplementation. In conclusion, the RBC n-3 index was increased and the general n-6:n-3 ratio was decreased in horses receiving 35-day dietary KO supplementation.

Effects of Crude Rice Bran Oil and a Flaxseed Oil Blend in Young Horses Engaged in a Training Program

Rice bran oil and flaxseed oil contain omega-3 fatty acids with the potential to reduce post-exercise inflammation and muscle damage. This study measures plasma interleukin-1β and creatine kinase and fatty acid profiles in lightly worked, young horses (Equus caballus) undergoing an exercise test after 60 days (d) of oil consumption, where the oil replaced 25% of concentrate calories. Treatments consisted of CON (no oil), FLAX (flaxseed oil blend), and RICE (crude rice bran oil). Blood was collected pre-exercise, and again at 1 min, 30 min, 24 h, 48 h, and 72 h post-IET. Data were analyzed by repeated measures ANOVA. Plasma creatine kinase activity was not different in CON during the study, greater (p < 0.05) in RICE from pre-exercise to 30 min post-exercise across all exercise tests, and lesser (p < 0.05) in FLAX at 30 min post-exercise on d 30 compared to d 0. Plasma interleukin-1β was greater (p < 0.01) in CON on d 60, but no differences were observed in FLAX and RICE throughout the study. Plasma alpha-linolenic and linoleic acids were greatest (p < 0.05) in FLAX after 30 d of inclusion, while CON horses had greater (p < 0.05) EPA across all exercise tests and DHA after 60 d. These results indicate that 60 d of inclusion of crude rice bran oil or a flaxseed oil blend may benefit lightly worked, young horses by reducing training-program-related increases in interleukin-1β, while a flaxseed oil blend may reduce exercise-induced increases in creatine kinase. Additionally, the flaxseed oil blend has the potential to increase plasma omega-3 and omega-6 fatty acids. Replacing 25% of concentrate calories with flaxseed or rice bran oil has potential benefits for young horses in training.

Dietary omega-3 fatty acid supplementation does not impair vitamin E status or promote lipid peroxidation in growing horses

Omega-3 (n-3; ω-3) fatty acids (FA) are often included in the diet for their potential health benefits. However, because oxidative potential is increased with the degree of unsaturation in vitro, polyunsaturated FA such as eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) may be at increased risk of lipid peroxidation. We aimed to determine the effects of dietary n-3 FA supplementation on antioxidant status and lipid peroxidation in yearling horses. Quarter Horses (mean ± SEM; 14.6 ± 0.2 mo) were randomly assigned to receive no n-3 FA supplementation (CON; n = 6) or 60 mg n-3/kg body weight from milled flaxseed (FLAX; n = 6) or encapsulated fish oil (FISH; n = 6). All horses received a basal diet of mixed grain concentrate fed individually at 1.5% body weight (dry matter basis) and ad libitum bahiagrass pasture forage. Blood samples were obtained before and after 70 d of supplementation to evaluate vitamin E, selenium, lipids, antioxidant status, and oxidative stress. Data were analyzed using a mixed model ANOVA with repeated measures. Supplementation with n-3 FA did not reduce serum vitamin E or Se and, in fact, elevated (P ≤ 0.0003) vitamin E status in FISH horses. At day 70, serum triglycerides were lower in FISH and FLAX horses than CON horses (P ≤ 0.02) and F2-isoprostanes were lower in FISH than CON horses (P = 0.0002). Dietary n-3 FA had no effect on cholesterol, reduced and oxidized glutathione, glutathione peroxidase, and thiobarbituric acid-reactive substances. In growing horses fed to meet their vitamin E requirements, supplementation with 60 mg n-3/kg body weight did not negatively affect vitamin E status or promote lipid peroxidation. Elevated vitamin E status in horses fed FISH, coupled with lower serum F2-isoprostanes, further suggest that the longer-chain, highly unsaturated n-3 FA, EPA and DHA, may actually attenuate lipid peroxidation.

Effects of dietary fish oil and alpha-tocopherol supplementation on selected blood parameters and fatty acid profiles in mares and their foals

The effects of fish oil (40 ml/day) supplementation, with or without synthetic all-rac-alpha-tocopherol-acetate (2,500 IU/day), during the last 65 days before expected parturition were investigated in 15 adult mares (553 ± 24 kg BW) and their foals. Mares were assigned to one of three diets: control (n = 5), control plus fish oil and alpha-tocopherol (n = 4; FO + AT) or control with just fish oil (n = 6; FO). Blood samples were obtained from the mares before a 15-day dietary adaptation period (T1) and from mares and foals the first (T2) and fifth (T3) days post-partum. Colostrum was collected at T2 and milk at T3. Routine haematological, biochemical and alpha-tocopherol analyses were undertaken on all blood samples. Fatty acid concentrations were determined in the foal serum and alpha-tocopherol concentrations measured in the milk and colostrum. Diet had no effect on haematology or biochemistry in the mares. Alpha-tocopherol concentrations were significantly higher at T2 & T3 in the FO + AT mares. Foal WBCs were higher in FO (11.33 ± 2.59 × 10⁹ /l), comparing to FO + AT and control groups (9.18 ± 1.24 × 10⁹ /l and 7.26 ± 1.03 × 10⁹ /l, respectively), at T3 (p < .05). There was no significant effect of the fish oil supplementation on the foal's serum fatty acid profile. In the FO + AT group, both colostrum and milk alpha-tocopherol concentrations (2.56 ± 0.36 and 1.36 ± 0.22 µg/ml, respectively) were higher compared than those of the FO group (1.33 ± 0.39 and 0.72 ± 0.31 µg/ml, respectively; p < .05). Additional 2,500 IU/day of synthetic alpha-tocopherol in the last 65 days of pregnancy increased alpha-tocopherol concentrations in colostrum and milk and the foal's serum. 40 ml/day fish oil, however, did not significantly increase serum eicosapentaenoic acid and docosahexaenoic acid concentrations in the foals.

Effects of Docosahexaenoic Acid-Rich Microalgae Supplementation on Metabolic and Inflammatory Parameters in Horses With Equine Metabolic Syndrome

Much of the equine population is obese and therefore predisposed to the development of additional health concerns such as equine metabolic syndrome (EMS). However, pharmacologic treatments for EMS are limited. Omega-3 fatty acid supplementation is a therapeutic strategy in humans with metabolic dysfunction that improves insulin sensitivity and reduces inflammation, but the effects of omega-3 fatty acid supplementation in horses with EMS are unclear. Therefore, in this pilot study, 10 mixed-sex and mixed-breed horses with EMS were fed a docosahexaenoic acid (DHA)-rich microalgae containing 16 g DHA/horse/d or served as controls for 46 days. Inflammatory status was measured using serologic enzyme-linked immunosorbent assay and in peripheral blood mononuclear cells (PBMCs) using flow cytometry and reverse transcription polymerase chain reaction. Circulating fatty acids, triglyceride, leptin, and adiponectin concentrations were also determined. Insulin and glucose dynamics were assessed with oral sugar test (OST) and frequently sampled intravenous glucose tolerance testing. Postsupplementation, treated horses had an increase in many circulating fatty acids, including DHA (P < .001). Treated horses also had lower serum triglycerides postsupplementation (P = .02) and a trend (P = .07) for reduced PBMC tumor necrosis factor α. Interestingly, after 46 days, control horses had an increase in insulin responses to the OST (P = .01), whereas treated horses did not (P = .69). These pilot data indicate that DHA-rich microalgae supplementation alters circulating fatty acids, modulates metabolic parameters, and may reduce inflammation in horses with EMS.

Physical response of dogs supplemented with fish oil during a treadmill training programme

The rise in popularity of dog sports competitions has led to the evaluation of improvements in dog physical performance. The potential benefit of dietary supplementation with fish oil (FO) on the physical performance of human beings and horses has been reported. However, such effect has not been studied in dogs. We therefore evaluated the effect of FO dietary supplementation on heart rate (HR), rectal temperature (RT) and thigh circumference (TC) in dogs during aerobic treadmill training, and further determined HR response and blood lactate (BL) concentration during an incremental exercise test. Using a cross-over design, eight male dogs were randomly assigned to two groups and received a standard balanced commercial diet (control, CG, n = 7) and the same diet supplemented with 54 mg FO/kg metabolic weight per day (FOG, n = 8). All dogs had 30-min treadmill sessions at 8 km/hr and 7.5% slope twice a week for 12 weeks. Assessment of HR and RT was performed before and immediately after each session; HR was also assessed 5 min after the end of each session. Thigh circumference was evaluated before each session. All dogs performed an incremental exercise test on the treadmill at 0, 6 and 12 weeks to evaluate HR response and BL concentration. Data were analysed using the mixed procedure (SAS 9.4). In FOG, pre-HR (-4.9%) and post-HR (-2.4%) values and post-RT (-0.3%) values were lower during treadmill training, whereas TC (+2.2%) values were higher as compared with CG (p < 0.01). Through the incremental exercise test, mean HR (week 6, -5.3%; week 12, -6.0%) values in FOG were lower than in CG (p < 0.05). In conclusion, FO supplementation slightly improved the physiological response of dogs to exercise during training.

Capacidade funcional em cavalos de salto suplementados com linhaça

Objetivou-se avaliar a suplementação com linhaça, como fonte do ácido graxo ômega-3, sobre a capacidade funcional de cavalos de salto. Foram utilizados seis equinos distribuídos em dois quadrados latinos 3x3 balanceados. Os grupos experimentais consistiram em níveis crescentes de linhaça (na forma de farinha e óleo de linhaça na proporção de 75:25, respectivamente), resultando nos tratamentos de 0 (controle), 60 e 120g/cavalo/dia de linhaça. Os cavalos foram suplementados por período de 30 dias. A atividade física consistiu em trabalho para salto no nível de equitação fundamental. As variáveis funcionais mensuradas foram índice de claudicação (IC), comprimento da passada e biometria da articulação metacarpofalangeana - MCF (circunferência e ângulo de flexão). Observou-se efeito significativo da suplementação com linhaça, independentemente da dosagem, sobre o IC. Ainda, o fornecimento de 120g de linhaça/cavalo/dia aumentou o comprimento da passada dos cavalos ao trote (P<0,05) e promoveu redução de 0,5cm na circunferência da articulação MCF (P<0,05) em comparação ao grupo controle. A suplementação de cavalos de salto com 120g/dia de linhaça promoveu maior comprimento da passada ao trote e redução de edema na articulação metacarpofalangeana, melhorando suas capacidades funcionais.

Parâmetros sanguíneos de cavalos alimentados com concentrados lipídicos submetidos a treinos aeróbicos montados

Avaliou-se o fornecimento de concentrados com baixo e alto teor de óleo de soja a cavalos atletas, submetidos a duas intensidades de treinos aeróbicos montados, sobre a resposta metabólica de parâmetros bioquímicos do sangue, de importância ao desempenho esportivo. Foram utilizados quatro cavalos, em delineamento experimental quadrado latino, com tratamentos em esquema fatorial 2x2 (duas inclusões de óleo de soja e duas rotinas de treinos aeróbicos). Os tratamentos foram compostos por teores de 5 e 15% de óleo de soja nos concentrados e duas intensidades de treinos montados por 40 e 60min, classificadas como aeróbicas. As amostras de sangue foram colhidas após o último treino de 40 ou 60min, de cada período experimental. Monitorou-se, após o exercício, os parâmetros bioquímicos, triglicerídeos (TG), colesterol total (CT), glicose (GLI) e lactato (LAC). Houve redução no teor TG (P<0,05) para cavalos consumindo 15% de óleo e treinados aerobicamente por 60 min., o CT elevou-se em função do aumento da inclusão de óleo (P<0,05), incremento LAC (P<0,05) em cavalos treinados por 60min., independente do nível de óleo ingerido (1,48mmol/L), bem como não se verificou efeito (P>0,05) dos tratamentos sobre GLI. Concluiu-se que, para cavalos atletas em atividade aeróbica, o oferecimento de concentrado com alto teor óleo de soja deve ser associado ao treino montado de maior intensidade.

Dietary supplementation of conjugated linoleic acid in horses increases plasma conjugated linoleic acid and decreases plasma arachidonic acid but does not alter body fat

Studies using dietary supplementation of eicosapentaenoic and docosahexaenoic fatty acids (FA) in horses report inconsistent anti-inflammatory results but consistently report an increase in plasma arachidonic acid (C20:4), the major substrate of cyclooxygenase (COX) II inflammatory pathway. Conjugated linoleic acid has shown anti-inflammatory effects in laboratory and food animal species, but effects of CLA supplementation in horses have not been reported. Our objective was to determine the effects of CLA supplementation on plasma CLA and C20:4 and body fat in healthy horses at maintenance. In a crossover study, 12 mature mares were blocked by breed, age, and BCS and separated into 2 treatment groups (n = 6/group). Groups were fed CLA and corn oil (CO; isocaloric control) for two 6-wk feeding periods, separated by a 4-wk period during which treatment was withheld. Corn oil or CLA supplement (55% mixed CLA isomers) was incorporated into diets at 0.01% BW/d. Mares were fed individually and restricted to dry lots to control forage intake. Rump fat thickness (RFT), BW, and BCS were measured before (d 0) and after (d 42) each feeding period. Blood was collected on d 0, 14, 28, and 42 of each 6-wk period for GLC analysis of plasma CLA isomers (cis-9, trans-11; trans-10, cis-12; and trans-9, trans-11) and C20:4. An ANOVA was conducted to compare the response of RFT, BW, and BCS of CLA-treated and control mares. A mixed methods analysis with repeated measures was used to detect differences in plasma FA concentrations. There were no differences in BW, RFT, or BCS between treatment groups. All CLA isomers present in the CLA supplement were greater in plasma of horses fed CLA compared with controls (P < 0.01). Additionally, plasma concentrations of C20:4 were decreased in horses fed CLA (P < 0.05). This decline in C20:4 may impact the COX II pathway and warrants further investigation. These results suggest that in an equine model, dietary CLA increases circulating concentrations of supplemented CLA isomers and decreases circulating C20:4. Examining physiological effects of CLA supplementation in horses at varying levels of growth, exercise, and progression of joint disease may offer insight to potential benefits of CLA in the horse.

Dietary fish oil reduces skeletal muscle oxygen consumption, provides fatigue resistance and improves contractile recovery in the rat in vivo hindlimb

Dietary fish oil modulates skeletal muscle membrane fatty acid composition. Similar changes in heart membrane composition modulate myocardial oxygen consumption and enhance mechanical performance. The rat in vivo autologous perfused hindlimb was used to investigate the influence of membrane composition on skeletal muscle function. Male Wistar rats were fed either saturated fat (SF), n-6 PUFA (linoleic acid rich) or n-3 PUFA (fish oil) diets for 8 weeks. Hindlimb skeletal muscle perfused using the animal's own blood was stimulated via the sciatic nerve (1 Hz, 6-12 V, 0·05 ms) to contract in repeated 10 min bouts. The n-3 PUFA diet markedly increased 22 : 6n-3 DHA, total n-3 PUFA and decreased the n-6:n-3 PUFA ratio (P < 0·05) in red and white skeletal muscle membranes. There was no difference in initial twitch tension but the n-3 PUFA group maintained greater twitch tension within all contraction bouts and recovered better during rest to produce greater twitch tension throughout the final contraction bout (P < 0·05). Hindlimb oxygen consumption during contraction was significantly lower in the n-3 PUFA group compared with the SF group, producing a significantly higher O2 efficiency index compared with both SF and n-6 PUFA groups (P < 0·05). Resting oxygen consumption was increased in recovery in the SF group (P < 0·05) but did not change in the n-3 PUFA group. Membrane incorporation of n-3 PUFA DHA following fish oil feeding was associated with increased efficiency of muscle O2 consumption and promoted resistance to muscle fatigue.

The effects of dietary N-3 and antioxidant supplementation on erythrocyte membrane fatty acid composition and fluidity in exercising horses

REASONS FOR PERFORMING STUDY

Fatty acid supplementation could modulate erythrocyte membrane fluidity in horses at rest and during exercise, but information is lacking on the effect of exercise.

OBJECTIVES

To assess the effect of exercise with, and without, an oral antioxidant supplementation enriched with n-3 fatty acids on erythrocyte membrane fluidity (EMF) and fatty acid composition in eventing horses.

METHODS

Twelve healthy and regularly trained horses were divided randomly into 2 groups: group S received an oral antioxidant cocktail enriched in n-3 fatty acid (alphatocopherol, eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) whereas group P was placebo-treated. At the end of 4 weeks, all horses performed a standardised exercise test (ET) under field conditions. Venous blood was sampled before starting treatment (TO), immediately before (T1) as well as 15 min (T2) and 24 h (T3) after ET. Spin labelled (16-DOXYL-stearic acid) red blood cell membranes were characterised using the relaxation correlation time (Tc in inverse proportion to EMF). Fatty acid composition (%) of the membrane was determined by gas-liquid chromatography.

RESULTS

Supplementation did not induce changes in EMF (T1 vs. TO) but significant changes in membrane composition were observed and there were increases in n-3 polyunsaturated fatty acid PUFA, n-3/n-6 ratio, and total n-3 fatty acids. Exercise (T2 vs. T1) induced a significant decrease of EMF in group P (Tc: +19%, P<0.05) and nonsignificant decrease in group S (Tc: +5%), whereas membrane fatty acid composition did not change in either group. During the recovery period (T3 vs. T2), EMF decreased significantly in group S (Tc: +29%, P<0.05) and nonsignificantly in group P (Tc: +18%) without any significant changes in fatty acid composition.

CONCLUSION AND POTENTIAL RELEVANCE

An enriched oral antioxidant supplementation induced changes in membrane composition, which modulated the decrease in EMF induced by exercise. Long chain n-3 fatty acid supplementation might therefore be beneficial.

Effect of dietary omega-3 fatty acid source on plasma and red blood cell membrane composition and immune function in yearling horses

To determine the effect of different sources of dietary n-3 fatty acids (FA) on plasma and red blood cell (RBC) FA composition and immune response, 18 Quarter Horse yearlings were randomly and equally assigned to 1 of 3 treatments: encapsulated fish oil (n = 6), milled flaxseed (n = 6), or no supplementation (control, n = 6). Fish oil contained 15 g of eicosapentaenoic acid (C20:5n-3) and 12.5 g of docosahexaenoic acid (C22:6n-3), and flaxseed contained 61 g of alpha-linolenic acid (C18:3n-3) per 100 g of FA. Horses had free access to bahiagrass pasture during the active growing season and were individually fed a grain mix concentrate at 1.5% BW/d. Fish oil and flaxseed were mixed into the concentrate in amounts to provide 6 g of total n-3/100 kg of BW. Horses were fed their respective treatments for 70 d. Blood samples were obtained to determine plasma and RBC FA composition and for isolation of peripheral blood mononuclear cells. Peripheral blood mononuclear cells were stimulated with concanavalin A and phytohemagglutinin (PHA) to determine lymphocyte proliferation and were challenged with lipopolysaccharide to determine PGE(2) production. In vivo inflammatory response was assessed on d 70 by measuring skin thickness and area of swelling in response to intradermal injection of PHA. Treatment did not affect BW gain, which averaged 0.6 +/- 0.03 kg/d. Horses fed fish oil had greater (P < 0.05) proportions of eicosapentaenoic acid, docosahexaenoic acid, and sum of n-3 in plasma and RBC compared with those in the flaxseed and control treatments. In addition, plasma arachidonic acid was greater (P < 0.05) and plasma linoleic and alpha-linolenic acids were less (P < 0.05) in the fish oil treatment compared with the flaxseed and control treatments. Dietary treatment did not affect lymphocyte proliferation or PGE(2) production. Across treatments, the peak increase in skin thickness was observed 4 to 8 h after PHA injection. At 4 h postinjection, horses fed fish oil and those fed flaxseed had a greater increase in skin thickness than those in the control treatment (P < 0.05) and horses fed fish oil had a larger area of swelling than those in the control treatment (P < 0.05). Skin thickness remained greater (P < 0.05) in horses fed flaxseed than in control horses 6 h after injection. Although fed to supply a similar amount of n-3 FA, fish oil had a greater impact on plasma and RBC n-3 FA content than did flaxseed. However, supplementing horses with both fish oil and flaxseed resulted in a more pronounced early inflammatory response to PHA injection as compared with nonsupplemented horses.

Fish oil reduces heart rate and oxygen consumption during exercise

Dietary omega-3 polyunsaturated fatty acids (PUFAs) are readily incorporated into heart and skeletal muscle membranes where, in the heart, animal studies show they reduce O2 consumption. To test the hypothesis that omega-3 PUFAs alter O2 efficiency in humans, the effects of fish oil (FO) supplementation on O2 consumption during exercise were evaluated. Sixteen well-trained men (cyclists), randomly assigned to receive 8 x 1 g capsules per day of olive oil (control) or FO for 8 weeks in a double-blind, parallel design, completed the study (control: n = 7, age 27.1 +/- 2.7 years; FO: n = 9, age 23.2 +/- 1.2 years). Subjects used an electronically braked cycle ergometer to complete peak O2 consumption tests (VO 2peak) and sustained submaximal exercise tests at 55% of peak workload (from the VO 2peak test) before and after supplementation. Whole-body O2 consumption and indirect measurements of myocardial O2 consumption [heart rate and rate pressure product (RPP)] were assessed. FO supplementation increased omega-3 PUFA content of erythrocyte cell membranes. There were no differences in VO 2peak (mL kg(-1) min(-1)) (control: pre 66.8 +/- 2.4, post 67.2 +/- 2.3; FO: pre 68.3 +/- 1.4, post 67.2 +/- 1.2) or peak workload after supplementation. The FO supplementation lowered heart rate (including peak heart rate) during incremental workloads to exhaustion (P < 0.05). In addition, the FO supplementation lowered steady-state submaximal exercise heart rate, whole-body O2 consumption, and RPP (P < 0.01). Time to voluntary fatigue was not altered by FO supplementation. This study indicates that FOs may act within the healthy heart and skeletal muscle to reduce both whole-body and myocardial O2 demand during exercise, without a decrement in performance.

Some commonly fed herbs and other functional foods in equine nutrition: A review

Most herbs and functional foods have not been scientifically tested; this is especially true for the horse. This paper reviews some of the literature pertinent to herbal supplementation in horses and other species. Common supplements like Echinacea, garlic, ginger, ginseng, and yucca are not regulated, and few studies have investigated safe, efficacious doses. Ginseng has been found to exert an inhibitory effect on pro-inflammatory cytokines and cyclooxygenase-2 expression. Equine studies have tested the anti-inflammatory effects of a single dose of ginger, post-exercise. Echinacea has been reported to have anti-inflammatory and antioxidant properties. Yucca contains steroid-like saponins, which produce anti-inflammatory, antioxidant, and anti-spasmodic effects. However, some herbs have drug-like actions that interact with dietary components and may contain prohibited substances like salicylates, digitalis, heroin, cocaine and marijuana. Horses fed garlic at >0.2g/kg per day developed Heinz body anaemia. Drug-herb interactions are common and caution needs to be taken when implementing 'natural product' usage.

Factors affecting clinical assessment of insulin sensitivity in horses

Insulin resistance is thought to be involved in the pathogenesis of many equine conditions such as pars intermedia dysfunction, equine metabolic syndrome, diabetes mellitus, hyperlipaemia, laminitis, endotoxaemia and osteochondrosis dissecans (OCD); whereas polysaccharide storage myopathy in Quarter Horses and equine motor neuron disease (EMD) have been associated with increased insulin sensitivity. However, it is clear that there is not one ideal test, in terms of both practicality and accuracy, for evaluating insulin sensitivity in horses and improved diagnostic techniques are required. This review sets out the background to the subject and identifies current knowledge regarding the measurement of insulin sensitivity by tolerance testing and clamping techniques. Factors affecting insulin sensitivity, such as breed, pregnancy, lactation, obesity and nutritional factors are discussed. In addition, the relationship with training, nutritional supplementation and drug administration are considered.

Circulating fatty acid profiles in response to three levels of dietary omega-3 fatty acid supplementation in horses

Fatty acids of the n-3 type confer health benefits to humans and other species. Their importance to equine physiology could include improved exercise tolerance, decreased inflammation, and improved reproductive function. The circulating fatty acid profile and the acquisition and washout of fatty acids in response to n-3 supplementation were determined for horses in the current study. A fatty acid supplement high in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid was fed to deliver EPA plus DHA at 0 (control), 10, 20, or 40 g/d to 16 mares (n = 4/group) for 28 d. Plasma was collected at -11, 3, 7, 10, 16, 23, 30, 37, 44, 70, and 87 d relative to the beginning of supplementation. Plasma was analyzed for the presence of 35 fatty acids by gas chromatography. Plasma EPA and DHA increased (P < 0.05) in a dose-responsive manner by 3 d of feeding and reached peak concentrations by 7 d. Peak EPA and DHA concentrations of the 40 g/d supplement group were approximately 13x and 10x those of controls, respectively. Plasma EPA and DHA demonstrated a steep decline (P < 0.05) from peak values by 9 d after cessation of supplementation and were near presupplementation values by 42 d. Omega-3 supplementation also increased (P < 0.05) concentrations of fatty acids C14:0, C17:1n-7, C18:1trans-11, C18:3n-6, C18:4n-3, C20:3n-6, C20:4n-6, and C22:5n-3 and decreased (P < 0.05) concentrations of C18:1cis-9 fatty acid. Seasonal effects, apparently unrelated to supplementation and likely due to the availability of fresh forage, were also noted. Unlike ruminants, there were no detectable concentrations of CLA in equine plasma. These results indicate that the circulating fatty acid milieu in horses can be influenced through targeted supplementation. Possible implications of increased n-3 plasma and tissue concentrations on specific physiological function in the equine remain to be elucidated.

Dietary fish oil supplementation affects serum fatty acid concentrations in horses

Thirteen horses of Thoroughbred or Standardbred breeding were used to study the effect of dietary fish oil supplementation on blood lipid characteristics. Horses were assigned to either fish oil (n = 7) or corn oil (n = 6) treatment groups for 63 d. The fish oil contained 10.8% eicosapentaenoic acid (EPA) and 8% docosahexaenoic acid (DHA). Each horse received timothy hay and a mixed-grain concentrate at rates necessary to maintain BW. Oil (corn or fish) was top-dressed on the concentrate daily at a rate of 324 mg/ kg of BW. The n-6:n-3 ratio was approximately 3.6:1 for horses receiving the corn oil diet and 1.4:1 for horses receiving the fish oil diet. Horses were exercised 5 d/wk during the study. Before supplementation, there was no difference in the concentrations of any serum fatty acids between the 2 treatment groups. The mean basal concentrations of EPA and DHA on d 0 were 0.04 and 0.01 mg/mL, respectively. After 63 d, horses receiving the fish oil treatment, but not those receiving the corn oil treatment, had increased concentrations of EPA and DHA (P <0.05). Fish oil supplementation for 63 d also increased the concentrations of C22:0, C22:1, and C22:5 fatty acids (P <0.05). Overall, horses receiving fish oil had a decreased concentration of n-6 fatty acids (P <0.05) and a greater concentration of n-3 fatty acids (P <0.01), resulting in a lower n-6:n-3 fatty acid ratio after 63 d (P <0.05). Serum cholesterol concentrations increased (P <0.05) during the supplementation period in horses receiving the corn oil but not in horses receiving the fish oil. Compared with horses receiving corn oil, horses receiving fish oil had lower serum triglycerides at d 63 (P <0.05). These results demonstrate that 63 d of fish oil supplementation at 324 mg/kg of BW was sufficient to alter the fatty acid profile and blood lipid properties of horses receiving regular exercise.

Supplementation of dietary long-chain polyunsaturated omega-3 fatty acids high in docosahexaenoic acid (DHA) increases plasma DHA concentration and may increase trot stride lengths in horses

Twelve mature and six 2-year-old Arabian horses were used to determine the effect of dietary long-chain polyunsaturated omega-3 fatty acid supplementation on plasma fatty acids and lameness. Lameness scores and stride lengths were measured on day 0. Horses were striated and pair-matched according to age, gender, stride length and, for mature horses, lameness score, and each horse was fed either a treatment diet containing 5.95 g of stabilized omega-3 fatty acids plus a fat carrier (FA), for a total of 19.4 g fat, or a control diet containing 49 g of corn oil (CO) for 75 days. Horses were exercised 5 d week− 1, and blood samples were drawn and body weights recorded on days 0, 25, 50 and 75. Lameness scores and stride lengths were recorded again on day 75. Total plasma omega-3 fatty acid concentrations were higher on all days in FA horses than in CO horses. Total plasma omega-6 fatty acids increased from days 0 to 25, remained elevated through day 50 and returned to baseline on day 75 in all horses. The ratio of plasma omega-6:omega-3 fatty acids was lower in FA horses. Horses on FA had increased plasma docosahexaenoic acid (DHA) on days 25, 50 and 75. No difference in walk stride length was noted; however, FA horses tended to have a longer trot stride after supplementation when compared with CO horses. No differences were seen in prostaglandin E2 (PGE2) metabolite or tumour necrosis factor-α as measured in blood serum. In summary, supplementing omega-3 fatty acids increases plasma DHA, although there was no overall increase in omega-3 in FA horses. While a trend to increase trot stride length was seen, no differences in lameness scores between treatments were noted.