Notes for breeders of common laboratory animals / edited by George Porter and W. Lane-Petter.

Date:
1962
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Notes for breeders of common laboratory animals / edited by George Porter and W. Lane-Petter. Source: Wellcome Collection.

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    1. GUINEA-PIGS 3 reduced from five with the first method to about three and a half with this method, the space required for a given number of sows is increased by about 70% and the labour involved in looking after the animals is increased. Some breeders find, however, that the additional number of animals reared per litter makes this the method of choice. Other breeders try to combine these two methods by removing the boar when the sows are obviously in pig. If care is taken to avoid more than one litter in a cage at one time, it is possible to combine the higher productivity of the second method with the economy in space given by the first method. The female guinea-pig should not be mated before she is 4 months old. The first litter produced is usually rather smaller in number, and the number born dead is higher than in subsequent litters. The next five or six litters are the largest, and thereafter the numbers decline, but the actual decline differs in different animals. It is im¬ portant, therefore, to watch the performances carefully and to cull unproductive animals from the herd. Although the young born in small litters grow fastest, it is a mistake to use these animals for breeding since the characteristic of small litters is thereby perpetuated. Any female that does not rear to weaning at least ten young per annum should be discarded. This means that in polygamous herds (where the boar runs with the sows all the time) at least two and a quarter young must be reared, on the average, per litter, and when animals are separated or the boar is removed for littering at least three per litter. These figures can easily be attained by well-fed healthy stock. It cannot be too strongly emphasized that the guinea-pig herd must be kept as a self-contained unit and no new stock introduced from outside. Breeding within the herd should not lead to any deterioration in the stamina or fertility of the stock. If it is desired to introduce a different colour or other characteristic into the herd, then animals from an outside source will have to be introduced, but it is important that before this step is taken the opinion be obtained of some competent authority, who will be able to advise on a safe source from which to obtain these animals. It is safer to obtain males since these are not so likely as females to break down if chronically infected, and they should be kept in quarantine for some weeks before being admitted to the herd. When they have mated some sows, it might be safest to dispose of them. On no account should adults be introduced into the herd merely to increase the numbers of breeding animals. If an increase in numbers is desired, young stock must be kept from the produce of the herd. This