461 Effects of maternal overnutrition on cartilage metabolism in the neonatal foal

Abstract Alterations within the extracellular matrix of articulating joints influence the prevalence of developmental orthopedic disease in horses. The potential developmental impact of maternal nutrition on extracellular matrix constituents in neonatal foals has not been investigated. To evaluate effects of third trimester overnutrition on cartilage metabolism in neonatal foals, 16 Quarter horse mares were used in a randomized design. Mares with confirmed breeding dates were stratified by BW, BCS, and expected foaling date, and randomly assigned to dietary treatments, beginning on d 235 gestation. All mares received ad libitum access to coastal bermudagrass hay (Cynodon dactylon) and 0.1% BW forage balancer daily (Empower Balance, Cargill Inc.). Control mares (CON; n=8) were fed to meet nutrient requirements during late gestation. The overfed treatment (HIGH; n=8) received an additional 40% above CON receiving the same diet plus 0.7% BW commercial concentrate (SafeChoice Mare and Foal, Cargill Inc.) daily until parturition. Maternal BW change during the experimental period for CON and HIGH mares validated the model (P=0.07), with gains of 26.4 ± 5.5 kg and 49.2 ± 5.5 kg, respectively. At 5-hr postpartum, foals were euthanized and synovial fluid collected via carpal arthrocentesis. Samples were analyzed for carboxypeptide of type II collagen (CPII), collagenase cleavage neopeptide (C2C), and aggrecan chondroitin sulfate 846 epitope (CS846) using commercial ELISA (IBEX Technologies). Data were analyzed using the MIXED procedure of SAS. Diet did not affect CPII or C2C concentrations (P>0.05). Foals maintained an average CPII:C2C ratio of 8.16 and 7.83 for CON and HIGH treatments, respectively. Synovial fluid concentration of CS846 was unaffected by diet (P>0.05). These data indicate that maternal overnutrition in the third trimester did not alter cartilage metabolism based on type II collagen and aggrecan synthesis within the carpal joint of neonatal foals.