How to get my pig to gain weight?

My pig was born in January. The day we have to weigh is may 25th. I weighted my pig saturday 9th of april and he only weighs 70 pounds. He is in a pen with 3 other pigs and my pig is the least dominate. The bigest pig weights 150 somethin. we thought my pig was getting run off but they have a whole bunch of feed buckets in the pen in all different corners. We have been going out there and feeding my pig treats but she just isnt that interested in eating. We are feeding this organic stuff that has 18% protien in it. They are also giving them cottage cheese, raw eggs, and avacados. I keep my pig at my friends house.