title: Effect of sperm numbers on fertility of frozen bull spermatozoa in skim milk diluent.
abstract: Insemination doses of 10, 15, and 20 million progressively motile spermatozoa prior to freezing were compared in a split-ejaculate fertility experiment involving 4,603 first service inseminations to 34 semen samples from six Angus bulls. Based on 60- to 90-day nonreturn rates, fertility was significantly lower for inseminating doses of 10 and 15 times 10-6 than 20 times 10-6 motile sperm (61, 62, and 70%). The 1-ml doses of skim milk diluted semen were frozen in glass ampules. The post-thaw number of motile sperm per ampule after freezing and storage for 3 wk in liquid nitrogen averaged 5.5, 8.4, and 12.4 times 10-6 for corresponding pre-freeze numbers of 10, 15 and 20 times 10-6 motile sperm/ml and ranged from 4.0 to 15.7 times 10-6/ml. Frozen semen packaged in ampules should contain more than 8.4 times 10-6 motile cells post-thaw per ampule.
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D002452:Cell Count; D002465:Cell Movement; D004542:Ejaculation; D005260:Female; D005298:Fertility; D005615:Freezing; D005632:Fructose / Q000494:pharmacology; D005990:Glycerol / Q000494:pharmacology; D007315:Insemination, Artificial / Q000662:veterinary; D008297:Male; D008892:Milk; D012661:Semen; D013094:Spermatozoa / Q000166:cytology*; D013696:Temperature; D013997:Time Factors
chemical_list: D005632:Fructose; D005990:Glycerol