The weight system in iLivestock is 'stand alone', meaning that any weights recorded are not used by other parts of the system so you can safely record weight in lbs in the weight fields. At this time the labels will be wrong (Kg) but you can simply ignore them for now. We will look at being able to change the labels to lbs in a future release. The export files produced (CSV) will also have Kg in weight column headers but you can manually edit these for now.