Guinea Pigs are very prolific, having about five litters a year, and
from two to five at a litter. Three is a safe average.
The females are sexually mature at a month, but, of course, should not
be bred at that age. Three months is plenty early enough and some
breeders wait until they are even older.
The period of gestation is from 65 to 70 days. The young ones are fully
developed when born
nd in a few hours are able to run around. They
begin eating other food in a day or two.
They should be weaned when about three weeks old and placed in separate
pens, separating the young males from the females. It is then well to
let the mother rest two or three weeks before being placed in the
breeding pen again.
It is best to let each female have not over four litters a year. The
young ones are apt to be stronger and there will be more of them in a
litter. You will get about as many of them per year with four litters as
with five and have better stock. Some breeders, especially for show
stock, get only three litters a year.
When your young females are about four months old, they should be placed
in the breeding pen. Best results and surer are obtained by keeping one
male with four or five females and letting them stay together until you
are sure each female is bred. They begin to show that they are with
young in about 30 days or sooner and get to be very large before giving
It is best to have several females with young together in the same pen,
as they will nurse each other's young indiscriminately and the little
fellows seem to know no difference. While the males do not kill the
little ones, still they should never be left in the pen with nursing
mothers, as they will bother them.
Many breeders do not have special breeding pens, but keep all of the
females together and put males in with them. This is hardly the best
plan, however. The females must not be allowed to litter in the big pen,
but always in special pens or hutches.
It is best to have different breeding pens or hutches, so you can get
young stock that is unrelated. You will have many chances to sell
breeding stock and it does not do to supply males and females that are
full brother and sister. By using care you can so breed your stock that
you can keep different batches of them that are not very closely
By line breeding, we mean breeding the same stock without getting new
males. It is the method used by breeders of fancy stock to get any
special color or marking. It is not inbreeding in the true sense of the
In line breeding you breed the father to his daughter and the son to his
mother. This arrangement is all right and gets splendid results. You
must avoid, however, breeding full brothers and sisters. It is also well
to breed pigs that are similar in color and marking. For instance: Breed
whites with whites and blacks with blacks, etc. By line breeding you can
get almost any color you want. If you wanted to get solid red, say, out
of a mixed lot, you should breed your reddest male to your reddest
female. Then breed the father to his reddest daughter and the reddest
son to his mother. Continue in this way and eventually you will get
For commercial purposes, however, we think it is best to get new males
every now and then. If you have only one male at the start, you should
get a new one when the young ones of your first litter are old enough to
breed. This will permit you to get stock not closely related and that
you can sell for breeding and pet purposes.
It is best to breed males and females of different ages. Have one older
than the other. The females should not be handled too much when they are
with young, as it is apt to injure them, and, of course, no animal
thrives as well when fondled. Always keep your strongest and best males
Too frequent littering tends to weaken both the mother and the little
ones. If you have a female that gives weak young that are dead at birth
or die soon after, give her a rest of several months before breeding her
again. It is best to have fewer litters and stronger stock.
The old males will sometimes fight when in the pen together, but it is
seldom that the females do not get along well together. If you have a
fighting male keep him in a place to himself, as he is apt to injure the
Good young breeding stock is to be preferred by one beginning to raise
Cavies, because they have a longer life before them and if you get old
stock you cannot tell how old they are. Guinea Pigs live to be about
seven or eight years old and if you buy young stock you have them for
their entire breeding age.