The breed of sow has a vital role in the successful rearing of piglets and the selection of a good female is paramount. Breed from a hybrid or multiple breed female that through her mothering ability exhibits good hybrid vigour and one that is supported by historical data from the genetic base. This should show good milking ability, number of pigs reared and low mortality. The larger the sow the more difficult it becomes for her to rear pigs, maintenance costs increase and there is a relationship between girth size and piglet mortality. A large girth results in bad teat placements at farrowing and inadequate or delayed intake of colostrum in individual pigs. Increased body size may also produce sows too large for existing farrowing crates.