Effect of a reproduction rhythm based on the body condition of rabbit doe on same serum parameters

Productive protocols based on standard (Control: artificial insemination (AI) 11 days post-partum) or Conditioned rhythm (AI only when the does reach a perirenal fat depot weight estimated between 15 and 30 g) were compared. Two groups of fifty New Zealand White females were inseminated for seven consecutive cycles. The kits were weaned at 26 days. On the day of AI, all the does were submitted to ultrasound scanning of the perirenal regions to measure fat thickness and to BCS evaluation. Live weight, perirenal fat weight estimated and cumulative BCS were higher (P<0.01) in the Conditioned Group. These does, compared to the controls, showed higher sexual receptivity and fertility rate (P<0.01) as well as number of live born (P<0.05). The higher progesterone value found in control rabbits (P<0.05) confirms the negative effect of lactation on both sexual receptivity and fertility (P<0.01). Control does had lower (P<0.05) T3 blood concentrations, reflecting their worst body status. Multiparous does had higher (P<0.01) leptin levels, that only in Conditioned group reflected a greater body condition. Insulin and glucose concentrations were slightly increased in control does compared to conditioned rabbits. Further investigations are needed to analyze other important metabolites and hormones and to confirm the effect of body status condition on long-term performance of rabbit does. In conclusion, compared to fixed insemination at 11 days post partum, the conditioned rhythm seems more adapted to the reproductive physiology of rabbit does as testified by their higher sexual receptivity and fertility rates and better body condition. It is also evident thatexcessive fatness of non-pregnant does should be controlled by reducing feed ingestion during the dry period. Both BCS evaluation and measurement of perirenal fat by ultrasound technique permit to manage properly the energy balance and to improve body status, reproductive performance and welfare of rabbit does. Hormonal and metabolite analyses represent a good tool for understanding the physiological mechanisms required to meet these objectives.