Effects of Dietary Flaxseed Oil Supplementation on Equine Plasma Fatty Acid Concentrations and Whole Blood Platelet Aggregation

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.

The Effect of Ethyl Esters of Linseed Oil on the Changes in the Fatty Acid Profile of Hair Coat Sebum, Blood Serum and Erythrocyte Membranes in Healthy Dogs

The aim of this study was to determine the effect of supplementation with ethyl esters of linseed oil on the fatty acid profile in hair sebum, blood serum and erythrocyte membranes in healthy dogs. The material for the study included hair and blood samples of adult beagle dogs. The experiment was performed in two periods: summer and winter. Each time it lasted 16 weeks. During the first 8 weeks, the dogs received a supplement, the amount of which was determined individually so that the ratio of α-linolenic acid (ALA) to linoleic acid (LA) together in the feed and supplement was 1:1. Hair coat and blood samples were collected on days 0, 56 and 112; i.e., before the start of supplementation, after 8 weeks of supplementation and 8 weeks after supplementation was completed. The study included a determination of the fatty acid profile with a particular emphasis on polyunsaturated fatty acids (PUFAs) and the ratio of omega-6 to omega-3 in hair sebum, blood serum and erythrocyte membranes. As a result of supplementation, a significant decrease in saturated acids and an increase in unsaturated acids was observed in hair sebum both in summer and winter and especially in omega-3 fatty acids; i.e., α-linolenic (ALA) and its derivatives eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The same relationships were observed in blood serum and in erythrocyte cell membranes in all the studied periods. Additionally, 8 weeks after the end of supplementation, the level of polyunsaturated fatty acids was still higher compared to the period before supplementation. Moreover, the supplementation resulted in a favorable decrease in the ratio of omega-6 to omega-3 acids in the tested samples, which persisted even after the withdrawal period.

Effects of dietary camelina, flaxseed, and canola oil supplementation on transepidermal water loss, skin and coat health parameters, and plasma prostaglandin E2, glycosaminoglycan, and nitric oxide concentrations in healthy adult horses

Camelina oil is derived from a low-input, high-yield crop and, in comparison to many other dietary fat sources currently used in equine diets, provides a greater amount of α-linolenic acid [ALA; (n-3)], than linoleic acid [LA; (n-6)]. However, no research exists assessing the effects of feeding camelina oil to horses in contrast to other commonly used oils. The objective of this study was to compare the effect of supplementing camelina oil to that of flaxseed and canola oil supplementation, on outcomes related to skin and coat health in horses. Thirty adult horses [23 mares, 7 geldings; 14.9 years ± 5.3 years; 544 ± 66 kg body weight (BW) (mean ± SD)] underwent a 4-week wash-in period consuming hay and sunflower oil. Following the wash-in period, horses were blocked by location, age, and BW, and assigned to one of three treatment oils for 16 weeks (370 mg oil/kg BW): camelina (CAM), canola (OLA), or flaxseed (FLX) oil. Blood samples were collected and plasma prostaglandin E2 (PGE2; ELISA), nitric oxide (NO; Griess Reaction), and glycosaminoglycan (GAG; DMMB) concentrations were measured on weeks 0 (n = 30), 14 (n = 24), and 16 (n = 30). On weeks 0, 2, 4, 8, and 16, transepidermal water loss (TEWL) was measured pre- and post-acetone application using a VapoMeter (n = 26), and a 5-point-Likert scale was used to assess skin and coat characteristics on the side and rump of the horses (n = 30). All data were analyzed with repeated measures ANOVA using PROC GLIMMIX in SAS. Independent of treatment, coat color, and quality increased from baseline. There were no differences in the outcomes assessed between the horses supplemented camelina oil and those supplemented canola or flaxseed oil. These results suggest that independent of treatment, all oil supplements improved coat color and quality in horses. This provides indication that camelina oil is comparable to existing plant-based oil supplements in supporting skin and coat health and inflammation in horses.

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.

Thirty-Two Weeks of Oral Supplementation with LinPro® Increases Hoof Growth in Healthy Mares

LinPro® is a commercial dietary supplement marketed to increase hoof growth and quality. Ten mature (5-15 years) non-pregnant Quarter Horse mares without existing hoof quality issues were used to test the hypothesis that 32 weeks of daily supplementation with 113 g of LinPro® would increase hoof growth rates as compared to non-supplemented controls. Hooves were trimmed at the start of the study and every 8 weeks thereafter. A mark was applied on the hoof wall surface at 2.5 cm below the junction of the hoof wall and coronary band. At each trimming, the distance between the mark and coronary band was measured and a new mark placed. For front hooves, horses assigned to LP had greater total hoof growth over 32 weeks (2.65 ± 0.15 vs. 2.18 ± 0.12 cm; P = 0.048; Figure 2) and tended to have greater hoof growth per 8 week trimming cycle (0.64 ± 0.03 vs. 0.55 ± 0.03 cm; P = 0.085) than horses assigned to CON. Horses assigned to LP had greater plasma biotin concentrations (2158 ± 69 vs. 636 ± 62 ng/L; P < 0.001) and proportions of erucic acid in hoof tissue (1.03 ± 0.08 vs. 0.76 ± 0.07 %; P = 0.049) as compared to CON. Further, the most abundant fatty acids in hoof tissue were stearic, palmitic, oleic, and linoleic acids. LinPro® may provide an effective treatment to improve hoof growth rates in horses with otherwise healthy hooves.

Dose-Dependent Increase in Whole Blood Omega-3 Fatty Acid Concentration in Horses Receiving a Marine-Based Fatty-Acid Supplement

The objective of this study was to determine the effects of an oral, commercially available, marine based omega-3 fatty acid (n3-FA) supplement on fatty acid characteristics in horse whole blood. Fifty healthy, adult horses of various light breeds were assigned to one of two treatment groups: Group 1 receiving 7.5g/day of the test supplement, and Group 2 receiving 15g/day of the test supplement. The supplement contained 0.092g docosahexaenoic acid (DHA) and 0.148g eicosapentaenoic acid (EPA) per gram. Therefore, Group 1 received 1.11g of EPA and 0.69g of DHA daily, while Group 2 received 2.22g of EPA and 1.38g DHA daily. Blood was taken at time of enrollment and after 6 and 12 weeks of supplementation. Blood was subjected to gas chromatography to quantify the fatty acid characteristics of whole blood. At both 6 and 12 weeks following supplementation, there was a significant increase in all n3-FAs evaluated, including DHA and EPA, compared to baseline values, with Group 2 significantly increased compared to Group 1 at both time points. There was also a significant decrease in omega-6 fatty acids (n6-FAs) between baseline and 6 weeks of supplementation in both groups, with a larger decrease seen in Group 2. The dose-dependent increases in concentration of all n3-FAs evaluated at all-time points validates the use of this product as a n3-FA targeted supplement in horses. These findings also suggest that dose of supplement has a greater effect on increasing whole blood n3-FAs compared to duration of treatment.

Effect of Dietary Flaxseed Oil Supplementation on the Redox Status, Haematological and Biochemical Parameters of Horses' Blood

Simple Summary

Flaxseed oils have long been used in animal feeding and human nutrition due to the beneficial effects of their biologically active substances, especially omega-3 polyunsaturated fatty acids (PUFA). This study aimed to evaluate the effect of the replacement of soybean oil (SO) with flaxseed oil (FO) in the horses’ diet on biochemical, haematological, and redox status parameters of the blood. We found FO contributed to an improvement of lipid profile, haematological parameters of the blood and enhanced antioxidant defence mechanisms of horses. This suggests that substitution of SO with FO in the diet of horses is beneficial for their health status.

Abstract

This study compared the effect of two dietary vegetable oils on plasma biochemical indices, haematological parameters, and redox status of horses. Forty riding horses (20 mares and 20 stallions) of the Malopolski breed were divided equally into two groups that were similar in terms of age, sex, and body weight (on average 530 ± 30 kg). The horses received soybean oil (SO) or flaxseed oil (FO) in the amount of 25 mL per 100 kg BW/day. After 60 days, blood was collected for biochemical and haematological analyses. The results show that horses receiving FO as compared to the SO group had significantly lower plasma levels of glucose, low density lipoprotein cholesterol, total cholesterol/high-density lipoprotein (HDL) ratio and triacylglycerols, as well as the activities of alanine aminotransferase and alkaline phosphatase. In turn, %HDL-TC and lactate dehydrogenase activity were significantly higher in the FO group. The inclusion of FO in the diet contributed to an increase in antioxidant indices: creatinine, vitamin C, copper, and zinc contents and also superoxide dismutase and catalase activities. The level of the end product of lipid peroxidation, i.e., malonyl dialdehyde, in the FO group as compared to the SO group was significantly lower. Moreover, FO caused an elevation in red blood cell indicators, lymphocyte count and lysozymes. In conclusion, FO exerts a beneficial effect by stimulating antioxidant defence mechanisms of horses and reducing the severity of oxidative stress. FO also improved the lipid profile and haematological parameters of the blood. The replacement of SO by FO is recommended based on these findings.

Incorporation of sunflower oil or linseed oil in equine compound feedstuff: 1 Effects on haematology and on fatty acids profiles in the red blood cells membranes

Eight trained horses (6 mares - 2 geldings, 6 Selle Français, 2 Trotteur Français, 12 ± 5.8 years old, 538 ± 72.5 kg) were offered three diets to potentially affect haematology and the fatty acids (FA) profiles in red blood cells (RBC) membranes. The control diet was composed of 50% hay and 50% concentrate containing mainly rolled barley (48%) and whole spelt (48%). In the case of sunflower oil diet, sunflower oil (62.0% of α-linoleic acid, LA) was incorporated at a rate of 8% and substituted by an equal proportion of barley. In the linseed oil diet, first cold-pressed linseed oil (56.0% of α-linolenic acid, ALA) was utilised at a similar incorporation rate of 8%. The experimental design consisted of three 3 × 3 latin squares with one being incomplete. Each period lasted 8 weeks. On average, the total feed intake (straw excluded) was 6.2 kg/day and the oil intake 0.278 kg/day. The oils significantly increased the concentrations of RBC, haemoglobin and haematocrit. The oils had no significant impact on the haematology profiles except that platelets tended to decrease in both oil-based diets. The most abundant FA in the RBC membranes of the control diet samples were in the decreasing order LA, C18:1n9-7, C18:0, C16:0 and the arachidonic acid (ARA) respectively. The sunflower oil supplementation slightly increased the amount of LA (36.23 vs. 34.72 mg/dl, p = 0.55) and C22:4n-6 (0.21 vs. 0.09 mg/dl, p = 0.22), while the decrease was observed in case of other FA (C16:1n-7, 1.08 vs. 1.42 mg/dl, p = 0.03), C20:3n-6 (0.22 vs. 0.31 mg/dl, p = 0.02), and ARA (1.17 vs. 1.63 mg/dl, p = 0.08). Linseed oil induced similar effects in the n-6 series FA profiles. In the context of practical applications, our results show that linseed oil incorporation in the diet could improve the haematology and the n-3 FA profiles potentially leading to an increased performance.

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.

Effects of two different dietary sources of long chain omega-3, highly unsaturated fatty acids on incorporation into the plasma, red blood cell, and skeletal muscle in horses

The objective of this study was to examine the effects of different sources of dietary omega-3 (n-3) fatty acid supplementation on plasma, red blood cell, and skeletal muscle fatty acid compositions in horses. Twenty-one mares were blocked by age, BW, and BCS and assigned to 1 of 3 dietary treatments with 7 mares per treatment. Dietary treatments were: 1) control or no fatty acid supplement (CON), 2) 38 g of n-3 long chain, highly unsaturated fatty acid (LCHUFA) supplement/d provided by algae and fish oil (MARINE) containing alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and docosapentaenoic acid (DPA), and 3) 38 g of n-3 LCHUFA supplement/d provided by a flaxseed meal (FLAX) containing ALA. Each supplement was added to a basal diet consisting of hay and barley and was fed for 90 d. Blood samples and muscle middle gluteal biopsies were taken at d 0, 30, 60 and 90 of supplementation. Plasma, red blood cell and skeletal muscle fatty acid profiles were determined via gas chromatography. Plasma linoleic acid (LA) and ALA were at least 10 and 60% less (P < 0.01), respectively, in the MARINE compared with the FLAX and CON groups. Plasma EPA and DHA were only detected in the MARINE group, and EPA increased 40% (P < 0.001) from d 30 to 60, and DHA 19% (P < 0.01) from d 30 to 90. Red blood cell LA and ALA were not different among treatments. Red blood cell EPA and DHA were only detected in the MARINE group, where EPA increased 38% (P < 0.01) from d 30 to 60, and DHA increased 56% (P < 0.001) between d 30 and 90. Skeletal muscle LA was at least 17% less (P < 0.001) in the MARINE group compared with the other treatments. Skeletal muscle ALA was 15% less (P = 0.03) in the MARINE group compared with FLAX and CON groups. Skeletal muscle EPA was at least 25% greater (P < 0.001) in MARINE group compared with other treatments and increased (P < 0.001) by 71% from d 30 to 60. Skeletal muscle DHA was at least 57% greater (P < 0.001) in the MARINE group compared with other groups and increased (P < 0.001) by 40% between d 30 and 90. As far as the authors are aware, this is the first study to demonstrate that dietary fatty acid supplementation will affect muscle fatty acid composition in horses. Incorporation of n-3 LCHUFA into blood and muscle depends directly on dietary supply of specific fatty acids.

Correlations between blood and tissue omega-3 LCPUFA status following dietary ALA intervention in rats

The aim of this study was to assess relationships between the fatty acid contents of plasma and erythrocyte phospholipids and those in liver, heart, brain, kidney and quadriceps muscle in rats. To obtain a wide range of tissue omega-3 (n-3) long chain polyunsaturated fatty acids (LCPUFA) we subjected weanling rats to dietary treatment with the n-3 LCPUFA precursor, alpha linolenic acid (ALA, 18:3 n-3) for 3 weeks. With the exception of the brain, we found strong and consistent correlations between the total n-3 LCPUFA fatty acid content of both plasma and erythrocyte phospholipids with fatty acid levels in all tissues. The relationships between eicosapentaenoic acid (EPA, 20:5 n-3) and docosapentaenoic acid (DPA, 22:5 n-3) content in both blood fractions with levels in liver, kidney, heart and quadriceps muscle phospholipids were stronger than those for docosahexaenoic acid (DHA, 22:6 n-3). The strong correlations between the EPA+DHA (the Omega-3 Index), total n-3 LCPUFA and total n-3 PUFA contents in both plasma and erythrocyte phospholipids and tissues investigated in this study suggest that, under a wide range of n-3 LCPUFA values, plasma and erythrocyte n-3 fatty acid content reflect not only dietary PUFA intakes but also accumulation of endogenously synthesised n-3 LCPUFA, and thus can be used as a reliable surrogate for assessing n-3 status in key peripheral tissues.

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.

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.

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.

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.

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.

Beneficial effects of alpha linolenic acid rich flaxseed oil on growth performance and hepatic cholesterol metabolism in high fat diet fed rats

The purpose of the study was to investigate the effect of flaxseed oil (FO), rich in alpha-linolenic acid (ALA) (18:3 n-3) on growth parameters and lipid metabolism of rats fed with high fat diet. High fat diet (HFD) resulted in significant alterations in hepatic lipids, increase in body weight gain and negative effect on lipoprotein metabolism. FO supplementation significantly lowered the increase in body weight gain, liver weight, plasma cholesterol, triglycerides, phospholipids, free fatty acids, high-density lipoprotein (HDL), low-density lipoprotein-cholesterol (LDL-C), very low-density lipoprotein (VLDL), LDL/HDL and TC/HDL ratio in HFD fed rats. FO significantly reduced the hepatic and plasma lipid levels indicating its hypolipidemic activity. On the other hand, oral administration of FO exhibited lower plasma lipoprotein profile as compared to HFD rats. Hepatic protection by FO is further substantiated by the normal liver histological findings in HFD fed rats. These data suggest that FO participate in the normal regulation of plasma lipid concentration and cholesterol metabolism in liver. No adverse effect of FO on growth parameters and plasma lipids in rats fed with fat-free diet. The results of the present study demonstrate that FO may be developed as a useful therapy for hyperlipidemia through reducing hepatic lipids, thereby proving its hypolipidemic activity.

Gastrointestinal protectants and cathartics

The purpose of this article is to provide the reader with an overview of gastrointestinal cathartics and protectants and to point out possible applications for use in the horse with gastrointestinal disease. Most of the treatments described in this article have been used by the authors with apparent success; however, controlled studies with subsequent publication in the scientific literature with respect to these treatments in the horse are, for the most part, lacking. The authors view this emerging field of treatment as exciting and look forward to substantiating the efficacy of several of the treatments discussed.