Characterizing the Gonadosomatic Index and Its Relationship with Age in Greater Cane Rat (Thryonomys swinderianus, Temminck)

Adebayo, A. O.; Oke, B. O.; Akinloye, A. K.

doi:10.21608/jva.2009.42311

Characterizing the Gonadosomatic Index and Its Relationship with Age in Greater Cane Rat (Thryonomys swinderianus, Temminck)

Document Type : Original Article

Authors

¹ Department of Veterinary Anatomy, University of Agriculture, Abeokuta.

² Department of Veterinary Anatomy, University of Ibadan, Ibadan.

³ Department of Veterinary Anatomy, University of Agriculture, .

10.21608/jva.2009.42311

Abstract

This work investigated the gonado- somatic index (GI) by weight and by volume and its relationship with age in the greater cane rat raised in captivity at Igbesa, a suburb of Agbara Industrial layout in Ogun state, Nigeria. The actual weights and volumes of the testes of 18 sexually matured male animals, obtained after sacrificing the rats, were used to evaluate the gonadosomatic indices. The results obtained showed that the cane rat has low investment in its spermatogenic tissue and spermato- zoa having GI by weight and by volume of 0.053% and 0.059% respectively, compared to other rodents like mouse (0.4% in Mus pahari, 3% in Mus spicilegus), 0.72% in gerbils, 0.3 - 9.1 in lemur and 0.88% in African giant rat. Also, it was observed that low relationship ex- isted between testicular size (r2 = 0.23, p< 0.05) and the GI (r2 = 0.41, p <0.05) in sexually matured males. The result showed that as the animal ages even with increased body weight its GI de- clines. These observations can serve as aid for farmers involved in captive rearing of this animal and contribute to the knowledge of the reproductive biol- ogy of the male cane rat.

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