The guine pig i have attacked the new one! HELP???

Where did bạn introduce them? If it was in the male's territory then that is probably why is he so defensive. Always introduce on neutral ground, and do so slowly.

link

This should provide good info about how to introduce them properly.

Also, why are bạn wanting to breed? There are already so many guinea pigs in shelters and rescues needing homes. bạn could also lose your gieo, lợn nái hoặc babies. Guinea pigs can also breed after six weeks of age - and will breed with their mother/father/siblings. What will bạn do with the offspring? Please seriously think of the consequences and repercussions of breeding Guinea Pigs.