PSII-10 The effects of an intra-articular inflammatory insult on synovial fluid trace mineral concentrations in growing horses fed inorganic or complexed trace minerals. (7th December 2018) - Millican, A
Abstract: Sixteen weanling Quarter horses (255 ± 22 kg BW) were used in a 56-d trial to determine trace mineral (TM) source effects on synovial fluid TM concentration following an inflammatory challenge. Horses were stratified by age, sex and BW then randomly assigned to dietary treatment: complete concentrate formulated with Zn, Mn, Cu, and Co as inorganic sources (CON; n=8) or complexed trace minerals (CTM; n=8). Added TM were at iso-levels across treatments and intakes met or exceeded NRC requirements. Horses were offered 1.75% BW of treatment concentrate and 0.75% BW coastal Bermudagrass ( Cynodon dactylon ) hay, as-fed. On d 42, an intra-articular lipopolysaccharide (LPS) challenge was conducted. Carpal joints were randomly assigned to receive intra-articular injections of 0.5 ng LPS derived from Escherichia coli 055:B5 or sterile lactated Ringer's solution (LRS) as a contralateral control. Synovial fluid was collected at pre-injection h 0, and 6, 12, 24, 168, and 336 h post-injection and analyzed for Mn, Zn, Cu, Co, and Se. Data were analyzed using the MIXED procedure of SAS. A diet×LPS×time effect was observed for Co, Cu and Se (P<0.05); concentrations peaked at h 6 and decreased to h 168 in both CON knees and CTM-LPS. A delayed peak was observed at h 12 for CTM-LRS. Peak Cu, and Se concentrations were higher in LPS knees and Co was highest in CTM-LPS. A diet×time interaction was observed for Zn (P<0.05). Zinc peaked at h 6 in CON and h 12 for CTM before decreasing to h 168. At h 168, CON had lower concentrations than CTM. A time×LPS interaction was observed for Mn (P<0.01). Manganese peaked at h 6 in LPS knees versus a later peak at h 24 in LRS knees. Data indicate acute joint inflammation altered synovial fluid TM concentrations and dietary source impacted degree of response.