What is the best age for breeding my guinea pig ?

If you really must breed your piggy, rather than provide a home for an existing 'home-seeking' piggy, then the best age for breeding your guinea pig for the first time is approx 5 months. NEVER breed a female guinea pig that is over the age of 12 months (unless she has previously had pups) as her pelvic bones will have fused and she will most likely lose her own and her pups life.