Hi there. First time on this site. I have a concern about some pigs I am currently raising. I have 6 Tamworth/Berkshire cross that are about 4 months old. The problem is the are only around 40 lbs a piece with one being around 60lbs. They have continuous water and feed that never runs out. I feed them a ration of corn and soybean meal of 4 parts corn and 1 part soybean meal. I figured by 4 months they should be quite a bit bigger. They all seem healthy but small. They are on a 1/8 acre field. Mother weighed around 500lbs and dad was about 400lbs. Any idea as to why they are so small? Any advice would be greatly appreciated.