Maternal Vitamin D Deficiency Increases the Incidence of Osteochondrotic-Like Lesions in the Distal Femur of Growing Pigs.

Abstract The current objective was to evaluate the hypoviatminosis-D (Hypo-D) swine model for osteochondrosis-like (OC-like) lesions in the distal femur. Maternal and neonatal vitamin D deficient diets were used at specific production phases to produce OC-like lesions. Sows were fed 1 of 3 diets during gestation and lactation that included either 0 (GD-), 325 (GD+), or 1750 (GD++) IU D3/kg diet. Pigs produced by those sows were then fed 1 of 2 nursery diets for 4 weeks supplemented with either 0 (ND-) or 280 (ND+) IU D3/kg diet. After the nursery phase, all pigs were fed recovery diets formulated with 280 IU D3/kg. Dietary treatment groups included GD-ND- (n=16), GD+ND- (n=20), GD+ND+ (n=19), and GD++ND+ (n=15) for a total of 70 pigs. Pigs were euthanized at 22 weeks of age and the entire distal femoral joints were dissected for computed tomography (CT) scans and image analysis using Mimics (Materialize software, Version 23) to quantify whole-bone mineral volume (mm3), whole-bone mineral density (g/cm2), and OC-lesion characteristics across the physis and articular surfaces (number and volume of lesions). The incidence of kyphosis and distal femoral OC-like lesions were evaluated using binary count data (0 = no observations of spinal curvature or femoral OC-like lesions) or (1 = observations of spinal curvature or femoral OC-like lesions). Pigs in GD-ND- group did not recover body weight, whole-bone density, or whole-bone volume compared with pigs in other dietary treatment groups (P < 0.05; Table 1). The GD-ND- pigs had the greatest incidence of kyphosis (81%) and large physeal irregularities (LPI) in the distal femur (88%), compared with other groups. The distal femoral LPI in GD-ND- and GD+ND- groups had larger lesion volumes (P < 0.05) compared with pigs in GD+ND+ and GD++ND+ groups. However, small physeal lesions (SPL) and articular surface lesions (ASL) did not follow the same response pattern to dietary treatments. Interestingly, the GD+ND+ group had the largest volume of ASL compared with other groups (P < 0.05). The contrast in differential development of the three categories (SPL, ASL, and LPI) of lesions in the distal femur raises interesting questions about biological responses to vitamin D deficient diets at critical time points in long bone development. The present results infer that the time in which a vitamin D deficient diet is fed to sows and their subsequent offspring may alter the location, number, and size of OC-like lesions in the distal femur. Further studies are needed to fully characterize LPI and track the timing of a vitamin D deficiency with the different developmental growth patterns of the vertebral column and distal femur physis and articular surfaces.