Mikey when your sows are pregnant you are not to give to much feeds.Thats what I was told.I
I will just elaborate on this.
On the first few days of pregnancy they do not give to much feed because they want the fetus inside the sow to be viable. To much feed sometimes would increase the body temperature of the animal thus it might affect the embryo inside the sow.
After a few days after the embryo settled/ implanted it self in the uterus then the feed needs to be increased to help for the development of the embryo.
In the latter part of pregnancy the feeds in changed to lactation for bone development and milk production. At this stage bone development of piglet is rapid and you need calcium to do it. One source of calcium is the feed lactation. If there is no source of calcium the sow will digest some of its own bone to give to its piglet to develop its own. This would result weak leg for the sow because of the bone cannibalism that happens.
After farrowing the sow is given more feeds some computes it as 200-250 grams per piglet+ maintenance.
it means if the sow maintenance is 2 kilos + it has 10 piglets x 250 grams =2500 grams or 2.5 kgs= 4.5 kgs of feed per day.