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 11 It is clear that many breeders are not getting the best results from their herds. Everything possible must be done to improve this situation, since the financial disadvantage imposed on a breeder by low pro¬ ductivity may be too great to allow him to continue in business. The results given here may be of some assistance in showing breeders which factors are of the greatest importance. 3. POST-PARTUM BREEDING IN THE GUINEA-PIG I. W. Rowlands When the guinea-pig is bred by the ordinary method (separation of the sexes before parturition), an interval of about 15 weeks elapses between the birth of succeeding litters. In other words it takes a sow 2 years to produce seven litters. It is not very widely realized that the guinea-pig, in common with several other laboratory rodents, has a period of heat and will mate within a very few hours after farrowing. This period is known as the post-partum heat. Thus, by the usual method of breeding, the chances of mating occurring at this heat are lost. If a sow farrows in the presence of a boar, there is a good chance that another pregnancy will be well advanced by the time she has reared her previous litter and another litter will be born 63-70 days later. This method of breeding reduces the interval between the births of two succeeding litters from 15 to about 10 weeks. A healthy sow should be capable of producing five litters in a year. Bruce and Parkes, using guinea-pigs of the M.R.C, strain kept continuously together in pairs, found that 74% mated at the post¬ partum heat. The young were healthy and strong and the breeding sows took the strain of this intensive breeding without any ill-effects. Pair-breeding cannot be applied economically on a very large scale because of the large numbers of males that would have to be maintained, and to overcome this disadvantage I tested the possibility of post¬ partum breeding in small colonies of animals in floor pens in a heated room, and the results obtained are described below. (A) Design of the Test A number of small floor pens 7 ft by 3 ft 6 in. were built with asbestos sheeting, the walls being 18 in. high. Variable numbers of animals, as shown in Table I, were placed in these pens, in some of which post-partum mating was allowed by keeping the males con¬ tinuously with the females (Method 1). Other pens were fitted with a