Dissertation
This laboratory-based study examined the effects of quinestrol and levonorgestrel
(singly and in combination) incorporated in bait on body mass and reproduction of the
roof rat (Rattus rattus ). A total of 140 R. rattus, (70 males and 70 females) were provided
with 10 g of bait containing quinestrol (QU) or levonorgestrel (LE) or a combination of
levonorgestrel and quinestrol (EP-1) at concentrations of (10 ppm and 50 ppm) for seven
consecutive days consecutively. After 7 days, animals were dissected and the ovary,
uterus, testis, seminal vesicles, and epididymis were weighed and examined. Bait
consumption and body weight decreased significantly (p = 0.0001) in treated compared to
control animals, with a minor difference between sexes. Quinestrol and EP-1 at 10 ppm
and 50 ppm increased the mass of the uterus and ovary of females (p = 0.0001), which
was associated with edema in the uterus. The mass of epididymis, testis, seminal vesicles,
were reduced and sperm counts and motility were significantly reduced (p = 0.0001)
particularly in the animals with QU and EP-1 at the higher concentrations. To determine
the effects of contraceptive hormones on reproduction, 50 ppm of QU and EP-1 were
used. A total of 160 animals of equal numbers and sexes were paired, keeping the ratio of
one female to one male. Pregnancy and litter production was significantly reduced
(p = 0.0249) in the treated pairs when compared to controls. It is concluded that quinestrol
and EP-1 have a significant impact on both males and females R. rattus reproduction
compared to levonorgestrel alone. These hormones will be very valuable when used as a
fundamental method in controlling R. rattu reproduction.