Oh, 4-H piggies? Maybe you should put that in your title to attract attention. I have pastured homestead pigs, so I can't help ya, sorry! They wouldn't win any prizes for fast weight gain, that is for sure. Cheap bacon is all I'm going for, and the pastured aspect.
We raised two pigs in a pen of hog panels and a house made of pallets with hog panels hooped over with a tarp as a roof.
We moved the house and pen about once a week and let them rip up our garden. Not sure you could do a 4H this way but it worked for us and was a lot of fun. The hogs ended up small but we only kept them for 4 months and werent really aiming for huge.
Storey's guide to pigs has a raising for show section.
For 4-H pigs the most common breeds are Hampshire and Yorkshire for project animals. You will want to find out the rules ahead of time if you are planning to auction. The most important is the dates for age qualifications.
Most 4-h'ers raise their hogs in a stall or smaller pen for faster growth. A 10'x10' pen is the average size, but a bit bigger for exersize will improve the fat ratio of the hog. We have pastured our hogs and had a decent growth.
Be sure to ask around or call your extention office for a list of breeders that have quality, fast growing stock. Weaners from these breeders will be more expensive, but it will pay off in the end to have a good growing hog.
Also remember that 4-H accepts crossbreeds and non registered animals for showing.
Feed a good grower ration to your pigs. This will help to keep them growing fast. You can also suppliment in some fresh veggies and other healthy table scraps.
Walking your pig at least twice per week will help build up muscle and will also help you with showing your pigs later on.
Two is better than one they say. When pigs are housed together they are said to grow better, just be sure to feed them separately for better growth.
Be sure to contact your 4-H extension office. They will have books for you to help you get started.