Developmental competence of antral follicles and their oocytes after gonadotrophin treatment of sows with gene polymorphisms for leptin and melanocortin receptors (Iberian pig)

Abstract

Purpose: To evaluate possible differences in follicle and oocyte developmental competence after gonadotrophin treatment in sows of obese and lean genotypes.

Methods: Follicle dynamics, ovulation rate and oocyte developmental competence to embryo were compared between females, of obese (n = 7) and lean genotypes (n = 10), treated with 1,250 I.U. of eCG and 500 I.U. of hCG.

Results: The obese genotype showed lower numbers of follicles growing to preovulatory stages (12.4 ± 1.8 vs 18.6 ± 1.0, P < 0.05), of corpora lutea (16.0 ± 0.9 vs 23.5 ± 0.9, P < 0.05), and of recovered oocytes/embryos (8.0 ± 1.3 vs 12.9 ± 0.9, P < 0.05). Thereafter, embryo viability rates also decreased when compared to lean genotypes (62.5 vs 77.6%, P < 0.05).

Discussion: To our knowledge, this is the first study analyzing the effect of obese genotypes on the ovarian response to exogenous gonadotrophins in a non-rodent animal model, the pig. A lower efficiency of gonadotrophin treatments for stimulation of follicle development and induction of ovulation was observed.

Fig. 1

Evolution of the number of small (1.5–2.9 mm, white section), medium-1 (M1, 3–4.9 mm, light grey section), medium-2 (M2, 5–6.9 mm, dark grey section) and large follicles (≥7 mm, black section) in lean (LWxL) and obese (Iberian) swine genotypes, at administration of eCG (0 h) and hCG (60 h). SEM values have been omitted for clarity of the figure

Fig. 2

Changes of plasma estradiol concentrations in lean (LWxL; grey bars) and obese (Iberian; black bars) swine genotypes, at administration of eCG (0 h) and hCG (60 h)