Effects of beta-carotene on the fertility of rabbits

Abstract

The aim of this study was to investigate the effects of beta-carotene added in the diets of New Zealand rabbits on the ovulation, fertilization ratio, LH and progesterone levels. Forty female and 4 male adult New Zealand rabbits were used. Female rabbits were divided into 2 groups consisting of 20 each. Group I consisted of experimental rabbits while Group II was kept as the control. Animals in the experimental and control groups were kept in separate cages but in the same husbandry conditions. For the animals in the experimental group, 2.8 mg/kg of synthetic beta-carotene was added into the diet for a month. The female adults in the control group were fed a normal diet. At the end of month, male rabbits were deliberately placed in cages with females for mating. Blood samples were taken from all female rabbits every 6 hours for 2 days after mating and the level of LH was measured in all samples. Blood was also taken at 4 day intervals for 30 days and the progesterone levels were measured. All females (in Groups I and II) were laparotomized 2 weeks after mating and the ovarial corpora lutea and fetuses were counted. The LH levels in Groups I and II were statistically analysed and no difference was found between 0, 12, 18, 24, 30, 36, 42 and 48 hours, but the difference between Groups I and II at 6 hours was statistically significant (p<0.05). The difference in progesterone values on days 0, 4, 8 and 20 between the groups was not statistically significant, but the difference at 12, 16 and 30 days was significant (p<0.05). This difference on days 24 and 28 was also significant (p<0.01). The numbers of corpora lutea taken from the two groups were similar. The number of fetuses in Groups I and II was different and the difference was statistically significant (p<0.05). The number of fetuses born alive was also different and was statistically significant (p<0.05). In conclusion, the results of this study indicated that the addition of beta-carotene in the rabbits' feed stimulated fertilization and increased reproductive performance. Therefore, beta-carotene can be used as a supplement in rabbit feed in order to increase reproduction.