Abstract:
This study was carried out to evaluate the effects of fertility control agents (quinestrol and levonorgestrel) on reproduction performance of multimammate rats (Mastomysnatalensis). A total of 316 individual Mastomysnatalensiswere used to evaluate consumption rate of bait and their effects on reproductive performance under laboratory conditions. Animals were fed with contraceptive baits for seven days, paired and sacrificed for histological observations. Results indicated that acceptance of the control bait was not statistically different (p< 0.001) from that of levonorgestrel at 10 ppm. Acceptance of bait treated with quinestrol at three concentrations (10 ppm, 50 ppm and 100 ppm) was significantly lower (p< 0.001) than plain bait and that of levonorgestrel treatments. Significant interaction effects of treatment and sex were observed (F (16,392) =10.007, p<0.001), with higher acceptance of treated bait for both levonorgestrel and quinestrol in female rats than male rats. Quinestrol, levonorgestrel and quinestrol/levonorgestrel combination significantly reduced testes, epididymis and seminal vesicles weight. Sperm concentration and motility were significantly decreased with increased abnormal sperms morphology. In female animals there were significant differences (F (2, 86) =3.28, p = 0.0423) in pregnancy rate compared to the control group. There were no observed differences in uteri and ovaries weights. All treatment concentrations of quinestrol, levonorgestrel and quinestrol/levonorgestrel combinations had significant effects on pregnancy compared to the control (p< 0.05). The most effective compound was quinestrol which reduced spermatogenesis at all concentrations. Levonorgestrel alone was less effective on male and female reproduction status. These results indicate that quinestrol and/or quinestrol/levonorgestrel combination have anti-fertility effects on M. natalensis.
