Influence of sperm number and seminal plasma on fertility of progestagen-treated sheep in confinement.
Progestagen-impregnated vaginal sponges + PMSG were used to synchronize oestrus in crossbred adult ewes which were inseminated 56 h after sponge removal with 0.5 ml diluted semen containing 400, 200, 100, 50 or 25 x 10(6) spermatozoa per insemination. The diluent was skim milk-citrate or pooled seminal plasma. There was no difference in reproductive performance due to the insemination medium. Fertility (no. of ewes lambing) after insemination of 400 or 200 x 10(6) spermatozoa was 68% and was similar to that observed after natural service at progestagen-induced oestrus. When less than or equal to 100 x 10(6) spermatozoa were inseminated, fertility fell markedly and the number of lambs per ewe inseminated decreased. A decrease in litter size also occurred. The data indicate that insemination of 200 x 10(6) spermatozoa, i.e. less than 10% of the number in a single ram ejaculate, allows normal conception rates in progestagen-treated ewes.
D000818:Animals; D004973:Estrus Synchronization; D005260:Female; D005298:Fertility; D003425:Flurogestone Acetate / Q000494:pharmacology; D006064:Gonadotropins, Equine / Q000494:pharmacology; D007315:Insemination, Artificial; D008098:Litter Size; D008297:Male; D011247:Pregnancy; D012661:Semen / Q000502:physiology*; D012756:Sheep / Q000502:physiology*; D013076:Sperm Count
D006064:Gonadotropins, Equine; D003425:Flurogestone Acetate