Weighing the pigs

The pigs we had before we 'weighed' almost every week. I say weight, but we measured them and then estimated the weight from that using a formula from our pig book.
We finally got round to doing Pinky and Perky for the first time. Initially they seemed to be half the weight for the same age. But it turned out I should have measured from between the ears not from the bottom of the neck, I had forgotten. Even then they are about 25 kg (maybe about 30%) lighter than the other pigs at the same age. The Noir de Bigorre (they are 50% Noir de Bigorre, 25%Pietrain and 25% large white) is known for being very slow growing and they were weaned quite a bit younger than the other guys we had so perhaps those things together explains it. We have been feeding them similar although maybe a bit less as they have a much larger area to forage in. They look very happy and healthy. We just wormed them to be on the safe side.