Reproduction is the process whereby an animal ensures the continuous existence of their genes in
the population by procreation. Reproduction presents a series of obstacles for both males and
females. Males have to ensure they are in peak physical condition in order to establish
dominance and compete for the attention of the opposite sex. Females need enough energy to
support their bodily needs whilst supplying energy to the growing foetuses and suckling young.
The current thesis investigated the pattern of ovulation in female as well as the effect of
photoperiod and food restriction on male gonadal development in wild caught South African
spiny mice (Acomys spinosissimus) from the Limpopo province in South Africa by using faecal
samples to measure hormone concentrations. A novel method, using faecal samples to monitor
reproductive function in Acomys spinosissimus was validated during this study. It was shown that
reproductive function can reliably be monitored in both sexes using enzyme immunoassays for
17-oxo-androgens in males and 20-oxopregnanes in females, respectively. Females were
randomly assigned to one of three treatments. Seven females were housed completely separated
from any male stimuli and represented the control group. The two experimental groups were
each made up of seven females. The separated treatment was housed in visual and olfactory
contact with intact males, separated by wire mesh. The paired treatment was housed with
vasectomized males, allowing full contact between the two sexes. Females from all three
treatment groups underwent normal follicular development with corpora lutea of ovulation
recorded for one female from the control and one female from the paired treatment. Progesterone
concentrations were compared between the different treatments using faecal hormone metabolite
levels. The progesterone concentrations were not affected by the different treatments; however,
the day of faecal sample collection influenced progesterone levels. The findings from the ovarian
histology and faecal progestagens strongly suggest a spontaneous pattern of ovulation. To
investigate the effects of photoperiod and food restriction, males were randomly assigned to one
of four treatment groups. The first two groups, consisting of six males each, were subjected to a
14L: 10D (LD) photoperiod. Within the LD treatment, one group was fed ad libitum (NR) whilst
the other group was subjected to a 10% food restriction (R). The remaining two cohorts were
subjected to the same feeding regime as mentioned above, but they were kept on a 10L: 14D (SD) photoperiod. Male spiny mice exposed to a long photoperiod had significantly greater testes
volume and seminiferous tubule diameters when compared to the males exposed to a short
photoperiod. Total body fat did not differ significantly when compared between the different
treatments. Males exposed to the long photoperiod also had significantly higher testosterone
concentrations when compared to the males exposed to the short photoperiod. Feeding regime
did not have any significant effect on any of the reproductive parameters investigated in this
study. During this study it was concluded that Acomys spinosissimus is a spontaneous ovulator
that is strongly photoperiodic with the availability of food resources enhancing the photoperiodic
effect. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Zoology and Entomology / Unrestricted
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:up/oai:repository.up.ac.za:2263/33164 |
| Date | January 2013 |
| Creators | De Bruin, Phillippus Rudolf |
| Contributors | Bennett, Nigel C., 1961-, prdebruin@zoology.up.ac.za, Medger, Katarina |
| Publisher | University of Pretoria |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Rights | © 2013 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
Page generated in 0.0029 seconds