A brood sow should be fed about four pounds daily of a 14-16% protein feed during gestation, depending on her condition. Three weeks before farrowing, increase the amount to approximately six pounds but withhold feed the day she farrows. If constipation is a problem, add Epsom salts, bran or oats to her feed. Gradually increase the sow's feed after farrowing to about 12 pounds per day. Use common sense: if she is getting fat, cut back; if too thin, feed more of the same feed - do not change the protein content. See I told you raising pigs is cool.
After weaning there are several advantages to selling the sow immediately (within three weeks): You avoid the trouble and expense of acquiring a boar for re breeding; The price of a cull brood sow is usually enough to buy a bred gilt; If you raised the gilt, and she is a year old, only 40% of the proceeds are taxed under the capital gains provision; There is a three month break between selling the litter as finished hogs and buying another bred gilt to farrow the following spring. Keeping hogs off the land during this time cuts down the likelihood of disease and parasites. It also gives you a break.