Abstract:
The reproductive characteristics of 34 female grasscutters (Thryonomys Swinderianus) were investigated to identify common features that could be used to formulate breeding strategies for grasscutters in captivity. The female's ability to manifest an oestrous cycle, mate, conceive, deliver and wean its young in captivity, as well as elicit signs of successful mating, conception and imminent parturition were investigated. Thirty-one (91.2%) females cycled erratically and mated within 2 weeks of pairing with the male, irrespective of the oestrous phase. Twenty-seven (87.1%) conceived, 2 aborted and 25 (92.6%) gave birth after 148-157 days to 2-6 pups per litter, totalling 98 neonates, which included 9 stillborn. The remaining 89 pups were successfully weaned at 6 weeks of age. All mated females presented post-mating vulval congestion, while those that became pregnant bled intermittently on the 32nd-38 th day after mating, Eleven (44%) of the pregnant females adopted the 'penguin posture' 2-3 days before delivery. The variations among the grasscutters with respect to all the parameters investigated (except the oestrous cycle length) were statistically not significant; suggesting that a common breeding programme could be put in place for management of grasscutters in captivity. Furthermore, since mating, pregnancy and imminent parturition were accompanied by visible cues, they could be used to enhance the practical management of the breeding colonies. In conclusion, the overall findings of this study showed that though the grasscutters of the study are still undergoing domestication, they exhibit fairly uniform characteristics and therefore the formulation of a common breeding programme is practicable.