PSXV-8 - Development of Imaging Techniques to Evaluate Dietary Interventions That Promote Regression of Osteochondrotic Lesions in a Growing Pig Model

Abstract: The current objective was to develop imaging techniques to characterize osteochondrotic-like lesions (OC-lesions) and evaluate the efficacy of dietary interventions to promote lesion regression and prevent lameness. Pigs (n=76) were weaned (~6kg) and fed 1 of 2 nursery diets for 3-wk with no supplemental vitamin D, (-D, n=60) or 280 IU D3/kg (+D3, n=20). Following the nursery, +D pigs were fed standard diets (+Ctl) and -D pigs were allotted to 1 of 4 diets (15 pigs/TRT) until 24-wk: 280 IU D3/kg diet, D3; 280 IU 25-OH-D3/kg, 25OH; 140 IU D3/kg+140 IU 25-OH-D3/kg, D3+25OH; 280 IU D3/kg+40ppm Mn, D3+Mn. Pigs were euthanized at 8, 12, and 24-weeks and femurs dissected for CT and MRI scans. CT scans were reconstructed in Mimics (Materialize software, Version 23) to quantify whole-bone mineral volume (BMV; g/cm3) and OC-lesion characteristics across the growth plate and articular surface (number, volume, surface area, location), as reported in Table 1. MRI images were used to validate lesions detected with CT. Differences in gain and feed intake were not detected. At 8-wk, BMV was reduced in D3 pigs compared with +Ctl; however, at 12-wk BMV was increased in 25OH and D3+Mn compared with D3 and D3+25OH pigs. By 24-wk BMV across all treatments was not different from +Ctl. No lesions were observed at 8 wk. Number of lesions per bone at 24-wk increased in D3+Mn compared with +Ctl pigs, 3.6 vs. 1.7, respectively (P< 0.05). Summation of lesion volume per bone at 24-wk tended to increase in 25OH and D3+Mn, 81.2 and 97.0 mm3, respectively, compared with +Ctl pigs, 60.6 mm3. Limitations of this study include low number of observations and low incidence of detected lesions in all treatments, with no differences between D3 and +Ctl. Although inferences about nutrient interventions are premature, we have developed methodologies to better characterize OC-lesions.