Abstract
Lameness in gilts and sows has an economic impact on pig production and is a major welfare concern. Study objectives were to compare subjective and objective lameness measurements and assess efficacy of chelated trace minerals in finisher pigs. Two dietary treatments: metal methionine hydroxy analogue chelate (MMHAC) supplied as MINTREX® Zn-Cu-Mn (Novus International, Inc.) supplemented at 80-10-20 mg/kg diet; and sulfates Zn-Cu-Mn supplemented at 120-20-40 mg/kg diet were fed. Four groups of pigs (50-70 kg; 8 pigs/grp) were fed dietary treatments for a duration of 8 wk prior to injection of 2 mg sodium urate crystals into the right rear distal interphalangeal joint. Data collection occurred at baseline, 6, 12, 24, 48, 72 and 144 hr post-urate injection. Measurements included gait scoring (0-4), a panel of serum biomarkers for synthesis and degradation of cartilage (P2CP, CTX2, C2C), bone (osteocalcin, CTX1) and static force-plate. A Proc Mixed GLM procedure of SAS was used and means were determined using a Tukey test. Urate injections resulted in elevated gait scores, peaking at 12 hr and similar to baseline at 72 hr; pigs fed MMHAC had lower gait scores (P< 0.01) compared to sulfate. C2C (P=0.09), CTX2 (P=0.10) and osteocalcin (P< 0.01) paralleled closely to changes in gait score, peaking at 12 h and returning to baseline at 24 to 72 hr. Osteocalcin (P=0.07) and osteocalcin: CTX1 ratio (P=0.05) were increased with MMHAC. These findings demonstrate that biomarkers can distinguish between healthy vs lame pigs and MMHAC, at lower concentrations vs sulfates, reduced gait score and increased osteocalcin.
Keywords: chelated trace minerals, lameness, pigs, urate