Date of Award

12-2011

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Animal and Veterinary Sciences

Advisor

Vernon, Kristine

Committee Member

Coverdale , Josie

Committee Member

Jenkins , Thomas

Committee Member

Sharp , Julia

Abstract

Conjugated linoleic acid (CLA) reduces inflammation via the inhibition of cyclooxygenase II , thus reducing prostaglandin E2 (PGE2) production. Conjugated linoleic acid has a suggested osteoclast-suppressive role in bone remodeling and osteoarthritis, which are dependent on bone resorptive stimulator PGE2. Bone resorption marker, deoxypyridinoline (DPD), and bone formation marker, bone alkaline phosphatase (BAP), have been modulated by CLA supplementation in other species. Recent research in equine exercise physiology investigated dietary supplementation of polyunsaturated fatty acids as a possible prevention and treatment for osteoarthritis, but CLA supplementation has putative effects on skeletal function or inflammation in horses has not been reported. Our objective was to determine the effects of CLA supplementation on PGE2 in synovial fluid, BAP and DPD in serum, stride length and fetlock flexion and extension at the walk and trot, and body condition in healthy horses at maintenance.
In a crossover study, 12 mares were blocked by breed, age, and body condition score (BCS) and separated into 2 treatment groups (n = 6/group). Groups were subjected to CLA and corn oil (CO) as an isocaloric control for 6 weeks (wk) separated by a 4-wk period during which treatment was withheld. Corn oil or CLA supplement (mixed isomers; source contained 55% CLA isomers) were incorporated into maintenance-level diets at 0.01% body weight (BW) per d over a six week period. Mares were fed individually and were restricted to dry lots to quantify forage intake. Synovial fluid, blood, rump fat thickness (RFT), BW and BCS were sampled before (d 0) and after (d42) of each feeding period. Walk and trot stride length and fetlock range of motion were assessed on d 0 and d 42 of feeding period 1 only. Immunoassay kits were used to quantify BAP and DPD in serum and PGE2 in synovial fluid.
There were no observed differences in BW, RFT or BCS between the CLA and CO groups. While plasma CLA concentrations were higher in horses fed CLA compared to controls (P < 0.001), synovial fluid PGE2, serum BAP and serum DPD did not differ with treatment. Additionally, stride length and fetlock extension were not different at the walk or trot between treatments, nor was fetlock flexion at the walk.
Despite absorption and incorporation of CLA into plasma, mares did not experience treatment effects on biochemical markers of joint inflammation, bone metabolism or kinematic performance. Examining the effects of CLA supplementation on horses at varying levels of growth, exercise, and progression of osteoarthritis may reveal more effects as to its potential benefits in the horse. Rate of dietary CLA incorporation, duration of supplementation, and isolated isomer studies may improve our understanding of these fatty acids in the equine diet.

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