SHORT TERM EFFECTS OF DIFFERENT DIETS ON OVARIAN FUNCTION AND OOCYTE MATURATION OF RABBIT NULLIPAROUS DOES

Determination of the nutritional needs in reproductive does has been intensively studied, but the direct influence of nutrition on the ovarian physiology is poorly known in rabbits. Some nutritional factors may influence oocyte maturation that is the first step affecting successful fertilization and preimplantational embryo development. In this context, leptin is a possible link between the nutritional status and the reproductive function. The goal of this work was to study the short term effects of feeding strategies during rearing period (from 11 to 16 weeks of age) on the endocrine and reproductive parameters of nulliparous rabbit does. A total of 40 New Zealand x California white rabbits were randomly allocated to two experimental groups (HL and SL) fed with rich fibrous diets with a high (HL: NDF 50 % DM, ADL 16 % DM) or a standard lignin content (SL: NDF 41 % DM, ADL 5 % DM). Ten does per group were euthanasized, five before (G1 group) and the other five (G2 group) after artificial insemination (AI). The remaining rabbits were used to measure the conception rate. Serum leptin concentrations, ovary and body weight, number of follicles ≥1 mm in size in the ovarian surface, ovulation rate, and blastocyst recovery rate were recorded. Cumulus oocyte complexes (COC) were aspirated from ovarian follicles ≥1 mm in size of one ovary and were matured in vitro. A total of 113 COC were treated progressively for cortical granules (CG) and nuclear staining and observed under a confocal laser-scanning microscope. Leptin levels were higher in SL than in HL group (5.49 vs. 4.53 ng/ml; P<0.04). However, the average weight of does (HL: 3526 g; SL: 3641 g