175 of what size and weight bales?

Yes many variables but we need to plan for the worst. Nothing wrong with having some hay left over when the cows start grazing.

Another question is storage - will these bales be in a shed or outdoors uncovered? If the OP is planning on feeding for 7 months he is pretty far north. In drier areas there is a lot less loss in outside storage then there is in typically wetter areas. etc.

The 2.5% dry matter method above and thinking of hay by weight rather than by number of bales usually avoids unpleasant surprises in the spring as calving time approaches.