peppa and georgie wrote:
Hello found this for you
Breeding Your Guinea Pigs:
Guinea pigs are rather easy to sex. If you pinch or squeeze the genital area the penis will extrude in young males. Adult males are quite obviously male. When I kept cavies, I was taught that female guinea pigs are fertile at as young as two months of age (55-70 days)! And that males mature slightly later. My favorite pocket pet husbandry book The UFAW Handbook also gives the same ages for puberty (fertility). You can read more about guinea pig pregnancy problems in another article.
However, a reader recently informed me that guinea pig females can become pregnant as early as three weeks of age and that males can be fertile as early as four weeks of age. I never separated males from females at so young an age and I have never observed pregnancies occurring so young but apparently this might happen. So play it safe and separate the males babies from the female babies as soon as you can determine their sex.
Female guinea pigs have estrus or fertile periods just after giving birth and periodically throughout the year. The length of their estrus cycle is sixteen and one-half days. They are fertile for 6-11 hours, usually beginning in the evening. They come into heat again shortly after birthing. Although female pigs are fertile at two months of age or earlier, they should not be breed until they are 4-5 month old and weigh a little over a pound. The male used should be about double her age to insure potency.
A bigger problem is breeding female guinea pigs for the first time when they are too old. At 7-12 month of age the femaleâs pelvic bones fuse, making natural delivery next to impossible. So guinea pigs of this age that are having a first litter often need it delivered by cesarean section (dystocia). Baby pigs arrive after a pregnancy of 60-70 days. They are precocious, that is, they arrive fully developed. Babies suckle their mothers for about three weeks (180gms) and then are able to eat the same foods as their parents. Litter size ranges between one and eight. Be sure to handle the babies often at this age so that they become tame.
I would sure like to know where this information came from because it is filled with many incorrect facts.
To sex a baby pig, a male will look like an i and a female will look more like a Y. To me, a male looks more like a donut with a dot in the middle. You can gentle push on the penis to check that way, but don't squeeze or pinch. Females can and do become pregnant at 3-4 weeks (I bought a 4 week old that had babies exactly 10 weeks later). Since babies can be sexed at birth, it is best to separate the males when they are 3-4 weeks, not when you can tell the sex of the baby.
The estrus cycle is about every sixteen days, year round. They are in heat for about two days. In that time, the sow may or may not breed. Sows can be very choosy. I've had a couple that took 4-5 months before they accepted the boar. Or the boar may just be shy. With practice you can tell when a sow is in heat. There is a mucus plug that blocks the opening unless the sow is in heat. After birth, the sow comes in to heat about 2-3 hours after birth for about 12 hours. She can be rebred by the boar so he should be removed from the cage before the birth.
The beginning breeding age is more or less correct, except every breeder has their own ideal age to breed the sow. The 7-12 month age is not a proven fact. Many experienced breeders sometimes wait until the sow is over 12 months to breed her for the first time, especially if they are showing her. The pelvic bones don't actually fuse, but the ligaments may not stretch as easily, therefore causing a harder birth. I have waited until sows were just under one year old to breed for the first time with no problems (meaning they gave birth after 12 months of age).
Babies are born as little miniatures of the parents. They begin to eat and drink right away, but nurse for approximately 3 weeks. They can nurse longer and is recommended if a baby is on the small side.
To add, cavies don't produce their own vit C, so they need a good source from their food. Pellets are not a good source as the vit C looses it's potency the older the pellets are.
Well you can say you tried right :] 
