Effect of venereal transmission of ovine ureaplasma on reproductive efficiency of ewes.

Rambouillet yearling ewes (n = 20) selected from a flock culturally negative for Ureaplasma sp were assigned randomly and equally to 2 groups. One group (principal) was bred to a ram experimentally infected with a specific serotype of an ovine ureaplasma. The other group (control was bred to a ram culturally negative for Ureaplasma sp. All the ewes in the control group conceived during the first estrous cycle, remained free of infection with ureaplasma, and lambed on schedule with only 1 lamb failing to survive. The ewes in the principal group became infected with ureaplasma immediately after coitus. Ureaplasmas were routinely isolated for all ewes in this group for 50 days after the first coitus. Only 3 ewes were culturally negative for ureaplasma shortly after lambing. Two ewes failed to conceive on the first estrous cycle and 4 lambs failed to survive. Several lambs from the ewes in the principal group were small and weak, and their birth weight was 0.64 kg less than that of lambs from the control ewes. One lamb in the principal group was mummified, whereas its twin appeared to be clinically normal. In sheep, ureaplasmosis appears to be a venereal disease possibly capable of causing infertility and low birth weights.