title: Comparison between natural service and artificial insemination with fresh or frozen sperm at an appointed time in the ewe.
mesh_terms: D000818:Animals; D004971:Estrus; D005260:Female; D005615:Freezing; D007314:Insemination; D007315:Insemination, Artificial / Q000662:veterinary*; D008297:Male; D011247:Pregnancy; D012098:Reproduction; D012756:Sheep / Q000502:physiology*; D013094:Spermatozoa; D014021:Tissue Preservation