_ CHAPTER VI. BREEDING
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 and 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 birth.
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 related.
Line Breeding.
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 word.
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 solid reds.
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 for breeders.
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 other males.
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. _