Influence of oral glucosamine supplementation in young horses challenged with intra-articular lipopolysaccharide.

Fourteen yearling Quarter horses (351 to 470 kg) were utilized in a randomized complete block design to evaluate potential of glucosamine hydrochloride (HCl) to mitigate intra-articular inflammation following a single inflammatory insult. Horses were blocked by BW, age, and sex, and randomly assigned to treatments for a 98-d experiment. Treatments consisted of a control diet (CON; = 7) fed 1% BW per d (as-fed) of concentrate only or a treatment diet ( = 7) of concentrate top dressed with 30 mg/kg BW glucosamine HCl (99.6% purity; GLU30) offered at 12 h intervals. Horses were maintained in individual stalls and offered approximately 1% BW per d of coastal bermudagrass hay (). Plasma and synovial fluid samples were obtained every 14 and 28 d, respectively, and stored at -20°C, before analysis of glucosamine via HPLC. On d 84, an intra-articular lipopolysaccharide (LPS) challenge was conducted on all horses to determine ability of dietary glucosamine HCl supplementation to mitigate joint inflammation and cartilage metabolism. Carpal joints were randomly selected to receive 1 of 2 intra-articular treatments and included sterile lactated Ringer's (control; Contra) only or 0.5 ng LPS solution (LPS) obtained from O55:B5 into the radial carpal joint. Synovial fluid was obtained at pre-injection h 0 and 6, 12, 24, 128, and 336 h post-injection, and was analyzed for prostaglandin E (PGE), carboxypeptide of type II collagen (CPII) and collagenase cleavage neopeptide (C2C) biomarkers by commercial ELISA kits. Data were analyzed using PROC MIXED procedure of SAS. Plasma and synovial glucosamine tended ( = 0.10 and = 0.06, respectively) to increase over time in response to GLU30 compared to CON. There was a treatment by time interaction ( ≤ 0.01), with GLU30 increasing plasma glucosamine concentrations at 28 and 42 d when compared to CON. A treatment by time interaction ( ≤ 0.01) was observed with GLU30 increasing synovial glucosamine levels at d 28 and 84 ( ≤ 0.01 and = 0.05, respectively). Intra-articular LPS increased ( ≤ 0.01) synovial PGE, C2C, and CPII levels. GLU30 decreased synovial PGE and C2C concentrations when compared to CON ( = 0.04 and = 0.05, respectively), while synovial levels of CPII increased ( ≤ 0.01) in GLU30 horses. These results indicate the potential for oral glucosamine HCl to mitigate intra-articular inflammation and influence cartilage turnover in a young horse model.

The effect of a limit-fed diet and slow-feed hay nets on morphometric measurements and postprandial metabolite and hormone patterns in adult horses.

Modern horse management systems tend to limit a horse's opportunity to forage, rely on meal feeding, and may contribute to the increase in equine obesity. The use of slow-feed hay nets represents an opportunity to extend foraging time while feeding a restricted diet. The objectives of this study were to determine if limit feeding combined with a slow-feed hay net would affect morphometric measurements and postprandial metabolite and hormone patterns in overweight adult horses. Eight adult Quarter horses (BW 563 kg ± 4.6 kg; BCS 7.2 ± 0.3) were used in a randomized complete block design, with 4 horses assigned to feeding hay off the stall floor (FLOOR) and 4 horses assigned to feeding from a slow-feed hay net (NET). Horses were fed in individual stalls at 1% BW each day, split evenly between 2 meals at 0700 and 1600 h. Body weight, BCS, neck and girth circumference, cresty neck score, and ultrasound measurements of average rump fat, longissimus dorsi (LD) depth, and LD thickness were taken on d 0, 14, and 28. Three 24-h blood samplings were conducted on d 0, 14, and 28 and were analyzed for glucose, insulin, cortisol, and leptin concentrations. Samplings occurred every 30 min for 3 h postfeeding, with hourly samples occurring between feedings. Horses feeding from the FLOOR took less time to consume their hay meal compared with horses feeding from the NET ( < 0.001). All horses lost weight over the 28-d period ( < 0.0001); however, no difference was observed between treatments. There was no difference in BCS, neck and girth circumference, cresty neck score, rump fat, or LD depth between days or treatments ( ≥ 0.25). There was an effect of day on LD thickness in horses feeding from the NET. Longissimus dorsi thickness was lower on d 28 compared with that on d 0 ( = 0.0257). Only time to peak insulin and peak cortisol were affected by treatment ( ≤ 0.037), with horses feeding from the NET having lower values than horses feeding from the FLOOR. Average glucose, insulin, cortisol, and leptin were affected by day ( ≤ 0.0102). Glucose and insulin values increased, whereas cortisol and leptin levels decreased throughout the 28-d study. The use of a slow-feed hay net coupled with a limit-fed diet appears to be an effective method for decreasing BW and maintaining more homeostatic levels of postprandial metabolites and hormones when feeding overweight adult horses.