الفهرس 
ACKNOWLEDGMENT
Reproduction in rabbitsOnly 14 pages are availabe for public view
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Abstract
Maintenance of pregnancy and reducing embryonic mortality are two essential demands for increasing the animal production.
In primate pregnancy, progesterone is essential for many homeostatic mechanisms necessary for gestation, including suppressing maternal immunity to prevent the rejection of the developing fetus and promoting quiescence to ensure that pregnancy is maintained until term
Vitamin E is essential for body functions as growth, reproduction, prevention of various diseases, and for integrity of tissues. Vitamin E deficiency was found to be the cause of reproductive failure and nutritional myodegeneration in a rabbit breeding colony
The hypothesis of this study is that the doe rabbit that gestate at first kindling may have not the capacity to produce sufficient progesterone , and may have inappropriate amount of vit.E necessary for the embryonic survival during early pregnancy
Therefore, the aim of this study was to determine the enhancing of the early embryonic survival of does rabbit that gestate at first time by exogenous treatments with long acting progesterone and vitamin E and to investigate the effect of these treatments on the second kindling
Progesterone itself might be too short-acting unless given more than once per day. Since multi-injection of P4 is nonpractical, single long acting progesterone injection will be used in this study
A total of 24 virgin female New Zealand White rabbits of 6 months of age with mean body weight 2.35 ± 0.49 kg were used in this study and divided randomly into 4 groups of 6 does per each.
- Does in the first group were injected i.m. by saline solution and considered as control for other groups.
- Does in the second group were injected i.m. by 1.0 mg/kg single dose of long acting progesterone 2 days after mating.
- Does in the third group were injected i.m. by 20 IU/kg of vitamin E every 3 days after mating until mid-pregnancy (day15).
- Does in the fourth group were injected i.m. by both progesterone and vitamin E. All treatments were provided after natural matings.
All does were weighed and the weight was repeated every 10 days throughout the experiment. After each kindling by approximately 12 h, all litters were weighed and the weight was repeated at weaning period.
Does were naturally mated and re-mating interval was fixed at 10 days after kindling and weaning age at 17 day. After mating by 7 days, does were exposed to the ultrasonographic examination to check pregnancy and non-pregnant does were re-mated until they become pregnant. Furthermore, numbers of developing embryos were also recorded by using Doppler Ultrasonographic examination at days 7, 10, 12,16 and 20 of pregnancy.
Blood samples were withdrawn from each doe at pre-mating, post-mating by 7 days and mid-pregnancy (day 15).
Progesterone was assayed by competitive immunoluminometric assay.
The productive and reproductive traits were estimated during the first and second pregnancy.
All does used in the first experiment were re-mated them naturally after 10 days of the first kindling with no any exogenous treatments. This experiment was done just to confirm the results obtained from the first experiment from one side and to ensure that the treatments had no negative influences on the second pregnancy and progeny from the other side.
The results of this study showed that:
- At first pregnancy, the increase in body weight was significantly higher in the group treated by p4 (0.20 kg) than in the control does (0.02 kg) during the transition from 10 d post-mating to 20 d after it, but it dropped upon the transition from mating to 10 d after mating. At the same period of gestation, the treatment by Vit. E was also significantly higher (0.19 kg) than in the controls, while the treatment by p4 + Vit. E achieved progressive increase (0.26 kg) in mean body weight compared with the controls (0.15 kg) and the other treatments.
- The DROP in body weight was insignificant between the treatment by p4 and the controls after first kindling, while it was significant between the treatment by Vit. E (-0.09 kg) and the controls (-0.19 kg). By contrast, at second kindling the DROP in the weight was significantly higher in the groups treated by p4 (-0.32 kg) and p4 + Vit. E (-0.33 kg) than in the controls (-0.09 kg) and Vit. E (-0.15 kg).
- Treatments didn’t effect significantly on gestation length either in the first pregnancy or in the second ones compared with thecontrol..
- Numbers of mating per first and second conception were significantly(P < 0.05) lower in the does treated by p4 than the control and Vit. E groups.
- Treatment with p4 improved significantly (P < 0.05) the rats of conception in both first and second pregnancy while treatment with Vit. E. in the first pregnancy improved significantly (P < 0.05) the rate of conception in the second pregnancy, and not the first pregnancy.
- The treatment with Vit. E alone in the first pregnancy had a beneficial effect on conception rates in the second pregnancy, and not in the first pregnancy.
- Treatment by p4 achieved significantly reduction(P < 0.05) in the rates of abortion at first kindling compared with their rate in the control does. Similarly, the rate of abortion in does treated by p4 + Vit. E was significantly (P < 0.05) lower than that in the control does. Further, all treated groups succeeded to pass through the second kindling without abortion compared with the control does (0.33 ± 0.21).
- Mortality rate was significantly (p<0.05) higher at weaning of kits born from the does injected by Vit. E alone than those injected by p4 + Vit. E and insignificant with p4 and control groups. Furthermore, the mortality rate was higher in the group treated by Vit. E at first kindling than at second kindling. No significant differences in the mortality rate were found either among the treatments themselves or between the treatments and the control group after the second kindling.
- There were no significant differences in the litter size at birth either among the treated groups or between the treatments and the control group in the two parities. Although the lack of significance among the groups in the first kindling, but the does injected by a single dose of long-acting p4 resulted in an increase in their kits (4.83 ± 1.08 ) born at birth compared with the does treated by Vit. E (2.67 ± 0.88) and the control group (3.50 ± 1.18). The same trend has been found in the second kindling, there were no significant differences in the number of kits born between the treatments and the controls.
- Also the significance was lacked in the mean numbers of kits at weaning either at first or second kindling.
- Significance was lacked in the mean kit weight of all treatments and the control does of both first and second kindling. While the significance was observed in the total litter weights at first kindling, since the does treated by p4 achieved highly significantly (p<0.05) rise in the total mean of litter weights (292.0 ± 31.30 g) than those treated by Vit. E (200.0 ± 25.60, g) and the control. No significant differences in the total mean of litter weight were found at second kindling between the does treated by p4, p4 + Vit. E and the controls.
- p4 concentrations after 7 and 15 days of pregnancy were significantly higher (P < 0.05) in does treated by p4 than the other treatments and the controls, Meanwhile, the p4 concentration continued in its rise to reach 12.45 ± 2.79 ng/ml in mid-gestation of does treated by p4 compared with the control does (5.11 ± 1.96 ng/ml). Further, there was significant positive correlation between conception rate and progesterone level of both first and second knidling, and progesterone concentration and total litter weight at first kindling.
- There was no any significant effect in the p4 concentration between the does treated by Vit. E and the controls
- The sonogram at the 7th day of mating showed that the gravid uterus containing anechogenic (black) amniotic vesicle in the lumen with hyperechogenic (white) eccentric mass, which represent the fetus. This findings were recorded in 89.%, 50.%, 75.%and in 55.% of P4, Vitamin E, P4 + Vitamin E and control group respectively .At 10th day .The number of the fetei could be counted. There were significant differences in the amniotic vesicles diameter in pregnant does between the P4 and control group (P < 0.05), where the amniotic vesicle diameter in the P4 vs. control group was (1.19 ± 0.11 vs. 0.71 ± 0.09 cm). There were no significant difference between Vitamin E and control . After 16 days the blood supply was clear in this stage for the fetus and the uterus. After 16 days , also, the number of the fetei could not be counted
- The overall results of this study confirm that single long acting progeseterone dose may be economically applied in rabbit farms because it improved doe body weight, numbers of service/conception and conception rate of both two kindling, reduced abortion of two kindling, and increased total litter weight at birth of first kindling, not the second ones. Otherwise, single long-acting progesterone had no significant effect on gestation length, mortality rate and litter size at birth of both two kindling.
These findings suggest that single dose of long -acting p4 improved the fertilization rate and maintained the embryonic survival in the early stage of pregnancy compared with the other treatments and the control group. Moreover, it also improved the fertilization rate and embryonic survival in the second pregnancy