Q. If off paddock infrastructure is used (cows are off paddock) for variable hours during all months of the year, should a feed pad or an animal shelter be selected?
It is effluent management that is important. If deciding between a wintering pad/animal shelter with a concrete feeding apron and a shelter plus a feed pad, it shouldn't matter, as long as the time spent on the feeding apron is the same as time spent on the feed pad. Effluent management of the concrete feeding apron is assumed to be the same as effluent management from a feed pad.
Here, timing becomes the issue. If time spent by animals in the shelter varies from month to month, but the time spent feeding (on the concrete feeding apron) is reasonably constant, then use a wintering pad/animal shelter. If, on the other hand, the time spent in the shelter and time spent feeding on the concrete feeding apron vary with time, then split animals between both structures.