Real-time PCR. VDR, CB, and TRPV6 mRNA expression levels in the different intestinal segments in the horse intestine (DD = duodenum, JE = jejunum, IL = ileum, CC = cecum, CAV = colon ascendens ventrale, CAD = colon ascendens dorsale, CD = colon descendens) were determined by real-time (TaqMan) PCR. Expression was normalised to the expression of β-actin. VDR mRNA was found in each intestinal segment, but the amount and distribution patterns showed distinct inter-individual variations between the animals investigated. There were no significant differences between VDR mRNA expression levels in the small and large intestine (p > 0.05) (Figure 2A). The duodenum expressed the highest levels of TRPV6 and CB mRNAs (p < 0.05) (Figure 2B, C).