Multiple mating enhances luteogenesis increasing corpus luteum perfusion area and progesterone production in ewes

Multiple matings in ewes reduce estrus length and induce a greater secretion of LH during the preovulatory surge. This study aimed to determine if multiple matings enhance corpus luteum (CL) development and functionality in ewes. Estrous cycles of 20 ewes were synchronized, and the onset of estrus was monitored every 3 h with rams without allowing mating. At the onset of estrus, ewes were assigned to two groups (n=10/group), allowing a ram to mate ewes every 3 h until the end of estrus (Mated group, 9.6 ± 1.0 matings, during receptive period) or not (Control group). To determine CL presence, size, and its blood perfusion, ovaries were scanned by transrectal ultrasonography, using B and color-Doppler modes, every 12 h until ovulation, and daily thereafter until 5 days after ovulation. Blood samples were collected every 24 h to analyze serum progesterone concentration. In the Mated ewes, estrus was about 11 h longer (37.2 ± 2.7 h vs. 26.4 ± 2.7 h; P=0.01) and the ovulatory follicle was larger (5.97 ± 0.01 mm vs. 5.08 ± 0.08 mm; P=0.02), than in the Control ewes. During the 5 days after ovulation, in the Mated ewes, CL perfusion (14.9 ± 3.1 % vs. 9.5 ± 3.1 %; P=0.0002) and serum progesterone concentrations (0.66 ± 0.11 ng/mL vs. 0.42 ± 0.11 ng/mL; P=0.02) were greater than in the Control ewes. Multiple matings with penis penetration and ejaculation modified the preovulatory process, enhanced luteogenesis and CL quality.