Identification of sexual receptivity in ewes by young sexually inexperienced rams

• Published in: Applied animal behaviour science Vol. 31; no. 1; pp. 83 - 90
• Main Author: Orgeur, P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1991; Elsevier
• Subjects: Computer Science; Life Sciences
• ISSN: 0168-1591; 1872-9045
• DOI: 10.1016/0168-1591(91)90155-Q

In sheep, the meeting of sexual partners in the precopulatory period does not depend only on male sexual activity. One major aim of this research was to identify the role of the partners during the phase of mutual recognition before copulation. The animals studied were inexperienced Ile de France rams between 14 and 15 months of age. They were observed individually, in the presence of sexually receptive or non-receptive ewes, for three 1-h periods at 1-week intervals. The first male sexual act was always an anogenital sniff, directed indiscriminately towards both the receptive and the non-receptive female. The first mounting was oriented toward the sexually receptive female in 16 out of 17 cases. The greatest proportion of anogenital sniffs observed during a test was significantly oriented toward the receptive female in the first test only, while the total number of nudges and mountings was more frequently oriented toward the receptive ewe over all tests. Independently of sexual acts, the male more often initiated the first contact (the head within 20 cm of another animal) which was preferably oriented toward the receptive ewe. The male and the sexually receptive female each initiated 50% of other contacts observed during all the tests. When contact was initiated by the ewe, it was by the receptive female in most cases. When rams initiated contact, they remained longer near receptive ewes than near the non-receptive ewe. When the females initiated the contact, the receptive ewe remained near the male longer than the non-receptive female. These results show that young sexually inexperienced rams are unable, even at a short distance, to identify the state of sexual receptivity of ewes, showing that the olfactory cue does not play a principal part. The active role of the sexually receptive ewe which can discriminate between sexually inactive and active rams in the bringing together of sexual partners, stimulates the response of the male and illustrates the importance of visual cues in this process. Indeed, the postural response of the ewe seems an important element of identification of its physiological state by the male and hence both sexual partners play a complementary role in the phase which precedes copulation.