A two-sample t-test with equal or unequal variances was used to test for differences in vitamin D3 and 25(OH)D3 in loin and subcutaneous adipose from the SUN versus control pigs at slaughter and to test for differences between summer and fall exposure pigs for serum and tissue vitamin D concentrations. Pearson correlation coefficients were used to determine associations between tissues and serum concentrations of vitamin D.