Figure 1. Glucose concentrations in ULF were higher (P = 0.05) in pregnant compared to open heifers on day 17 (A). Among pregnant heifers, there was no effect (P = 0.88) of fertility classification on ULF glucose concentrations (B). ULF glucose did not differ (P = 0.66) among open fertility-classified heifers (C). Glucose in plasma was not different (P = 0.20) between pregnant and open heifers (D). Among pregnant heifers, plasma glucose was affected by the interaction between fertility group and conceptus length (P = 0.02; E). Among the open animals, IF heifers had higher (P = 0.04) plasma glucose concentrations compared to HF heifers (F).