Potential Benefits of Rice Bran Oil for Lightly Worked Young Horses.

Abstract Rice bran (RICE) and flax (FLAX) oils contain omega-3 fatty acids with the potential to reduce post-exercise muscle damage. This study compared plasma essential fatty acid profiles, creatine kinase (CK) activity, and lactic acid (LA) concentrations in lightly worked young horses undergoing a 16 min incremental exercise test (IET; 16.1, 19.3, 22.5, and 25.7 kph) after 60 d of supplementation. Treatments consisted of none (CON; n = 4), FLAX (n = 4), or RICE (n = 4) oil. Horses received their energy requirement as 40% from concentrate and 60% from hay, with oil replacing 25% of concentrate calories. Blood was obtained before, 1, and 30 min post-IET. Data were analyzed by repeated measures ANOVA. On d60, alpha-linolenic acid was greater in FLAX (2.3±0.2 g/100g) than RICE (1.5±0.2 g/100g; P = 0.01), and docosahexaenoic acid was higher in CON (1.4±0.3 g/100g) and RICE (0.9±0.3 g/100g) than FLAX (0±0.3 g/100g; P < 0.01). In CON horses, CK activity was increased on both IET days at 30min post (1.9±0.4 U/L; P < 0.01). In FLAX and RICE horses, CK activity increased 30 min post IET on d0 only (FLAX=2.2±0.1 U/L; P=0.02; RICE=1.9±0.06 U/L; P = 0.01), with no increase on d60 (P > 0.06). For CON, LA concentrations were not different at 1 min post-IET between d0 and 60 (P >0.7) but were different at 30min post (d0=1.0±0.1 mmol/L; d60=0.4±0.1 mmol/L; P = 0.04), In FLAX, LA was greater at 1min post-IET on d60 (2.8±0.1 mmol/L) than d0 (1.5±0.1 mmol/L; P = 0.057), with no differences between days at 30min post-IET (P >0.07). In RICE horses, LA was not different at 1min post IET across days (P >0.1), however was lower at 30min post-IET on d60 (d0=1.7±0.1 mmol/L; d60=0.2±0.1 mmol/L; P < 0.01). Sixty days of rice oil supplementation may benefit lightly worked horses by reducing post-exercise lactic acid concentrations, CK activity, and increasing docosahexaenoic acid.