257 Survey of Biological Measurements Used to Determine Bone Mineralization in Pigs Across the US Swine Industry

Abstract Pigs (n = 192) from 64 commercial sites across 14 production facilities in the Midwest USA were used to evaluate baseline biological measurements used to determine bone mineralization in pigs. There were 3 pigs selected from each site representing: 1) a clinically normal pig, 2) a pig with evidence of clinical lameness, and 3) a pig with a history of recent low feed intake within a hospital pen (sick pig). Pigs ranged in age from nursery to market weight, with the three pigs sampled from each site representing the same phase of production. For each pig, blood, urine, and the right and left metacarpal, fibula, 2nd rib, and 10th rib were collected and analyzed. Serum was analyzed for Ca, P, and 25(OH)D3 as part of the serum chemistry profile. and. Each bone was measured for bone density and ash (non-defatted and defatted methods). Bone density was measured on each bone based on Archimedes principle. For defatted bone ash, all bones were cleaned of tissue and then placed in Soxhlet extractors containing petroleum ether for 7 days as a means of removing water and fat. Bones were then dried at 105°C for 7 days and then ashed in a muffle furnace at 600°C for 24 h. Healthy pigs had increased (P < 0.05) serum calcium and 25OHD3 compared with sick pigs, with lame pigs intermediate (Table). Healthy pigs also had increased (P < 0.05) serum phosphorus compared with sick and lame pigs, with no differences between the sick and lame pigs. For defatted bone ash and bone density, there was a pig type × bone interaction (P < 0.001). There were no differences between pig types for the fibulas, 2nd rib, and 10th rib, but metacarpals from healthy pigs had greater bone ash compared with sick pigs, with lame pigs intermediate. For bone density, healthy and lame pigs had greater (P < 0.05) bone density than sick pigs for the metacarpals and fibulas, with no difference observed for the ribs. In summary, there appear to be differences in serum analysis between a healthy, lame, and sick pig. Differences in bone mineralization between pig types were observed in the metacarpal and fibula, but not ribs. The metacarpal appears to be the most sensitive bone to detect differences in bone mineralization between pig types. There was also considerable range in values within pig type across production sites.