It is easy to set about breeding guinea-pigs. All one has to do is allow the boar and sow to run together and nature will do the rest. Both sexes will show sign:- of sexual behaviour at an early age but this is a form of play or preparation for more serious behaviour when older. No young may be produced. Actually it is unwise to allow a sow to breed too soon; some are capable of breeding as early as three or four month but five months is probably a better age to start. A male may be used for breeding as early as three month (although many breeders frown on breeding from males before five months).
The simplest method is to have a pair living together in the same hutch from five months of age. These will produce a succession of litters with the minimum of attention. The gestation period on the average s 69 days, with a variation of 67 to 70 days. This is in extraordinarily long period for such a small animal. However, it means that the young are born fully developed. Baby guinea-pigs are born with their eyes open and covered with hair. They are strong enough to walk within a few minutes. Though it is usual to provide nesting material, the mother rarely makes a proper nest as do other rodents. The mother and young imply use it to lay on. The average litter is three or our but as many as six young is possible. The male s not removed, as he will not interfere with the litter. Indeed the babies will huddle close and use him as a hot water bottle!
The baby guinea-pigs commence nibbling at solid food after about three days. This is the time when food tucked away by the parents and young will increase rapidly and a watch should be kept that they are never short of food. A mash at this time is especially good for the young. The young may be weaned at about three weeks. Bowls of milk or bread and milk can be given and they will love it but it is not obligatory provided the diet is varied and adequate. Likewise, special food at weaning is not necessary.
When the parents are running together continuously, the boar will normally mate the sow almost immediately after birth of the young. This is natural and does no harm to the mother. Her young will be weaned long before the next litter arrives. However, it means that if you do not wish to have too many litters, the male must be taken away from the mother before her litter is born. There is rarely any difficulty in knowing when the female is pregnant. Her tummy swells to quite a size.
Quite a large hutch is required when a male is living with several females and overcrowding may occur if these are allowed to litter together. Because pregnancy is so easily detected, removal of the female to a separate, smaller, hutch is common practice. She can have her babies, and rear them before being returned to the communal hutch. This is the sort of breeding which can be followed if one is the fortunate possessor of a valuable boar.
Sexing of young guinea-pigs is apt to be confusing for the beginner. This is because the external signs differences between the sexes are small and requires a practical demonstration if they are to be understood. However, the sex can be determined by gentle palpation. A finger should be pressed on the stomach just in front of the vent. If the animal is a boar, a small tube (male organ) will become visible, whereas, if it is a sow, no tube will appear. If you are doubtful, request a guinea-pig breeder to show you the difference. It is advisable to separate the sexes before four weeks of age otherwise the boars start chasing the sows and squabbling among themselves.