Tamsaddle,
Yes we recommend increasing the feed gradually.
To quote from the book :
"Once the litter is born the sow will have her normal 6lb a day, then add 1lb per day up to the number of piglets. So a sow with 12 piglets has 6lb (2.73kg) on day 1, 7lb (3.18kg) on day 2, up to 18lb (8.18kg) on day 12. She will stay on this until the piglets wean. Most sows do not need this quantity and you will find they leave food in the trough, so decrease the amount. Some sows bring up a litter and remain in relatively good condition, others will go very thin and lose hair. For these type of sows we will increase the feed again. Just make a judgement on how much more you think she needs, you can’t really over feed a sow who is feeding a litter, the figures are a guide. We tend to find that most sows will eat about twice or two and a half times their normal ration i.e. about 12lb to 15lb (5.5kg-6.5kg)"
As we say, these are guidelines, not forumulas, watch your sow and adjust accordingly.