In my opinion it's a basic flaw in the standard wind-down advice. There is a big difference between the weights before and after wind down nobody seems sure of the answer to this question.
Although it's rarely mentioned there is a better calculator than the Jackson and that's the Hailey. It's more sensitive for example you can dial up for a male or female animal. And it's based on much more recent studies.
Worth checking out for those who find these things useful. This widget will do the sum online for you:
http://www.ahailey.f9.co.uk/cond.htm