Dietary supplementation of conjugated linoleic acid in horses: establishment of baseline values on bone turnover, synovial prostaglandin E2, and gait kinematics

Abstract

Conjugated linoleic acid (CLA) has shown anti-inflammatory effects in laboratory and food animal species by modulating production of proinflammatory cytokines and inhibiting cyclooxygenase 2 (COX2), reducing prostaglandin E2 (PGE2) production. Bone remodelling may also be affected by CLA. Thus, CLA may reduce inflammation consistent with joint disease. Effects of CLA supplementation in horses have not been previously reported. This study aimed to determine baseline values of CLA supplementation on bone turnover, synovial PGE2 and gait kinematics in mature, idle horses. It was not expected that CLA would affect bone metabolism or gait kinematics in this animal model, as COX2 pathway should not be upregulated. In a crossover study, 12 mature mares were blocked by breed, age, and body condition score and separated into two treatment groups (n=6 per group) fed CLA or corn oil (CO; isocaloric control) for two 6-week feeding periods, separated by a 4-week period when oil treatment was withheld. Corn oil or CLA supplement (55% mixed CLA isomers) was incorporated into diets at 0.01% body weight/day. Blood and synovial fluid samples were collected before (day 0) and after (day 42) each feeding period for evaluation of serum bone alkaline phosphatase (BAP) and deoxypyridinoline (DPD) and synovial PGE2. Stride length and fetlock flexion and extension were captured on day 0 and 42 of period 1. ANOVA was conducted to compare the response of BAP, DPD, and PGE2 of CLA-treated and control mares. Kinematic data were analysed with Student t-tests. Dietary CLA supplementation did not affect serum BAP or DPD, synovial PGE2, or stride length (all P>0.05). This study provides a baseline for CLA supplementation on bone metabolism and gait kinematics in horses; CLA supplementation in horses at varying levels of growth, exercise, and progression of joint disease may now be more revealing.