Here are some factors that can influence this:
* Individual health: Some guinea pigs may be able to breed longer than others depending on their overall health.
* Diet and environment: A healthy diet and a clean environment can help guinea pigs stay healthy and able to breed for longer.
* Stress: Stress can negatively impact a guinea pig's reproductive health.
* Genetics: Some breeds of guinea pigs may be more prone to fertility issues than others.
It's important to note that guinea pigs can still be fertile even after they've stopped being receptive to mating. So, even if your guinea pig is older and no longer shows signs of breeding, it's essential to take precautions if you have a male and female living together.
To ensure your guinea pig's health and well-being, it's always a good idea to consult with a veterinarian for advice on their reproductive health.