Mean levels of serum plasma 25(OH)D at sacrifice were significantly lower than pre-surgical levels (F= 22.08, p<0.0001), decreasing lines indicate serum plasma vitamin D from pre-surgery to sacrifice. There was a significant grouping effect of levels of dietary vitamin D adjusted chow (F= 496.03, p<0.0001). Mean values are plotted as a function of spinal segment fused via manual palpation (MPF+, solid line) or not fused (MPF-, dashed line). SAS-Mixed model was used with a term for repeated measures of serum plasma vitamin D (pre-surgery vs. sacrifice) with dietary vitamin D as a grouping variable. The test for interaction between serum D and dietary was not significant (P=0.08) and the greatest contribution was from the HD, hyper-vitamin D dietary group.