54 Influence of dietary Saccharomyces cerevisiae fermentation product on cartilage metabolism in young exercising horses challenged with intra-articular lipopolysaccharide

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Dietary Saccharomyces cerevisiae fermentation product (SCFP) has the ability to optimize the intra-articular environment of horses, but its efficacy in young, exercising horses is not fully understood. Thirty Quarter Horse yearlings (374 ± 25 kg BW; 562 ± 16 d of age; 15 fillies, 15 geldings) were used in a 60 d study to investigate the effect of dietary SCFP (TruEquine®C, Diamond V Mills Inc.) on cartilage metabolism following an acute inflammatory insult, hypothesizing that SCFP would increase cartilage metabolism. Horses were stratified by BW, age, and sex and randomly assigned to dietary treatments (n = 10/group): 0 mg/kg BW (CON), 46 mg/kg BW SCFP (TRT1), or 92 mg/kg BW SCFP (TRT2) top-dressed to a custom-formulated concentrate void of microbials and offered at 1% BW/d (as-fed) every 12 h. On d 0, 21, 42, and 56 BW was obtained and intake adjusted accordingly. Daily grain and supplement orts were negligible across treatments. Horses were housed individually (3.6 × 7.3 m) and offered ad libitum Coastal bermudagrass hay and water. Horses were exercised on a progressive workload for 30 min/d, 5d/wk using a free-stall exerciser. On d 46, horses underwent an intra-articular lipopolysaccharide (LPS) challenge. Each horse's radial carpal joints were randomly selected to receive either 0.5 ng LPS or sterile lactated Ringer's solution (LRS) as a contralateral control.Synovial fluid obtained pre-injection (h 0) and at 6, 12, 24, and 336 h post-injection was analyzed for c-propeptide of type II collagen (CPII) and collagenase cleavage neopeptide (C2C) by commercial ELISA. Rectal temperature (RT), heart rate (HR), respiration rate (RR), and carpal circumference (CC) were recorded immediately before each arthrocentesis. Data were analyzed using PROC MIXED of SAS v9.4 and mean separation was achieved with orthogonal contrasts. The delta in BW exhibited a quadratic dose response (P ≤ 0.01) where CON horses were heavier than TRT1 and TRT2 on d 56. Diet did not influence HR, RR, or RT (P ≥ 0.25). There was an LPS × time interaction for CPII (P ≤ 0.01), CPII:C2C (P ≤ 0.01), CC (P ≤ 0.01), and a tendency in C2C (P = 0.09) for concentrations to be greater in LPS joints at 6, 12, and 24 h than LRS joints. Regardless of injection, CPII, C2C, and CPII:C2C did not return to baseline through h 336 (P ≤ 0.04). Dietary SCFP did not influence (P ≥ 0.42) biomarkers indicative of cartilage metabolism. Although, intra-articular LPS increased cartilage turnover in young exercising horses, the response was not affected by dietary SCFP.