Effect Of Dietary Energy Level And Light Intensity On Reproductive Performance And Body Condition Of Rex Rabbits

The experiment was conducted to investigate effects of energy level and light intensity on reproductive performance and body condition of Rex-rabbit does used circle production system. In the energy requirement experiment, a total of 150 rabbits(mean body weight 3.56±0.17kg) were used in the study. Rabbits were divided randomly into three groups(40 replicates per treatment, 1 rabbit per replicate), 42-d circle production system were used, diets containing DE 9.2,9.7,10.2MJ/kg, respectively. Three gestations were recorded in this study and blood samples were collected at 15-d during the first two gestations. Production experiment indicates that lactation capability(P = 0.0062), body weight of postpartum(P = 0.0021)after first gestation and weaning litter weight(P = 0.0006)were very significantly affected by different levels of energy. Body weight of 21-d of gestation of first(P = 0.0475) and third(P = 0.0302)gestation were significantly affected by different levels of energy. Besides, the values of creatine kinase(P = 0.0015) and triglyceride(P = 0.0013) in blood serum of Rex-rabbit does used 42-d circle production system were very significantly affected by different levels of energy. The values of high density lipoprotein cholesterol(P = 0.0368), total cholesterol(P = 0.0476) and glucagon(P = 0.0159)were significantly affected by different levels of energy, other serum biochemical indices were not affected. In conclusion, the suitable DE level is 10.2MJ/kg for Rex-rabbit does used 42-d circle production system which can keep the body condition and improve reproductive performance.In the light intensity experiment, a total of 144 Rex-rabbits and 49-d reproductive rhythm was applied in this study. Rabbits were divided randomly into three groups(48 replicates per treatment, 1 rabbit per replicate) and feed under three different light intensities: 60lux(L), 80lux(M), 100lux(H). Does’ bodyweight, the kindling rate, the litter size and the mortality of the kits of the first three consecutive reproductive cycles were evaluated. Ovaries were collected from 18 rabbit does(6 per group) and the ER-α, FSHR, LHR, Gn RHR-I, PGR, GHR m RNA expression were examined with real-time QT-PCR. The results showed that no difference was observed among all reproductive indices under the three light intensities and no difference was observed among the m RNA expression of ER-α, FSHR, LHR, Gn RHR-I, PGR. However, light intensity had a significant effect on the bodyweight at first insemination, second insemination and second postpartum(P < 0.05) and also had a tendency to effect the bodyweight at first postpartum(P = 0.0894). However, no difference was observed on the bodyweight of the third cycle(P > 0.05). The expression level of GHR m RNA was significantly higher in group L than group M and group H(P < 0.05). But, no difference was observed between group M and group H(P > 0.05). These observations suggest that a light intensity have no effect on the reproductive performance of rabbit does, but higher light intensity have a negative effect on bodyweight at the beginning of the experiment and the effect disappear after second gestation.