53 Hemp seed oil as a novel fatty acid supplement for horses

Abstract

Polyunsaturated fatty acids (PUFA) play a role in regulating the body's response to inflammation. Most grains fed to horses are high in linoleic acid (LA), a pro-inflammatory n6 PUFA, compared with α-linolenic acid (ALA), an anti-inflammatory n3 PUFA. Recent interest in hemp (Cannabis sativa) seed oil (HSO) as a PUFA source has arisen due to its unique fatty acid (FA) profile, which includes γ-linolenic acid (GLA), an n6 PUFA with anti-inflammatory properties. Dietary GLA is rapidly converted to dihomo-γ-linolenic acid (DGLA), a precursor to anti-inflammatory eicosanoids. Manipulating dietary FA may lead to alterations in tissue FA profiles in the horse which could promote a reduced inflammatory response. Thus, our objective was to determine if oral supplementation of HSO for 28 d would cause detectable changes in FA composition in synovial fluid (SF) and skeletal muscle (MUS). Six Thoroughbred geldings (11 ± 3.2 yrs, 568 ± 26 kg BW) were used in a crossover experiment with 2 consecutive 63d periods. Horses were offered a control (CON) basal diet of hay and concentrate or the basal diet with the addition of 166 mL HSO delivering 5g GLA. Diets were designed to be isocaloric. Over 7d, HSO was introduced gradually, maintained for another 28d, and then removed and horses resumed basal diets for an additional 28d. Horses were weighed, and body condition score (BCS) assessed weekly. MUS and SF samples werecollected on d0, d35, and d63 of each period. MUS biopsies were taken from the middle gluteus muscle at a depth of 8cm. SF was collected from the left carpus joint. FA were extracted from MUS and SF and analyzed by GC. Individual FA are represented as g of FA per 100g of total fatty acids. Data were analyzed using Proc MIXED in SAS (v.15.1 SAS Institute Inc., Cary, NC). No changes in BW or BCS were observed throughout the study. In SF, GLA was detected after 28d of HSO supplementation (0.32 ± 0.06g/100g) but not at any other time point. On d 28, horses supplemented with HSO also had greater SF DGLA (0.31 ± 0.04g/100g) than CON (0.19 ± 0.04g/100g; P = 0.04). MUS ALA tended (P = 0.07) to be greater in horses fed CON compared with HSO. No other differences were observed for FA in MUS or SF. These results indicate that 28d of HSO supplementation can modify FA profiles in equine skeletal muscle and synovial fluid. This could potentially influence inflammation signaling molecules and subsequently the inflammatory response, however, longer studies with more horses are needed to determine peak incorporation and the effects of varying quantities of HSO in the diet.