Breeding soundness evaluation and semen analysis for predicting bull fertility.
Bull fertility is influenced by numerous factors. Although 20-40% of bulls in an unselected population may have reduced fertility, few are completely sterile. Breeding soundness refers to a bull's ability to get cows pregnant. A standard breeding soundness evaluation identifies bulls with substantial deficits in fertility, but does not consistently identify sub-fertile bulls. In this regard, the use of frozen-thawed semen (from bulls in commercial AI centres) that meets minimum quality standards can result in pregnancy rates that differ by 20-25 percentage points. Although no single diagnostic test can accurately predict variations in fertility among bulls that are producing apparently normal semen, recent studies suggested that a combination of laboratory tests were predictive of fertility. This review is focused on recent developments in prediction of bull fertility, based on assessments at the molecular, cellular and whole-animal levels.
Kastelic
J P
JP
Agriculture and Agri-Food Canada, Lethbridge Research Centre, Lethbridge, Canada. kastelicj@agr.gc.ca
Thundathil
J C
JC
D000818:Animals; D001947:Breeding / Q000592:standards*; D002417:Cattle / Q000502:physiology*; D005260:Female; D005298:Fertility / Q000502:physiology*; D007315:Insemination, Artificial / Q000662:veterinary; D008297:Male; D011237:Predictive Value of Tests; D011247:Pregnancy; D012661:Semen / Q000166:cytology / Q000502:physiology*; D013075:Sperm Capacitation / Q000502:physiology; D013081:Sperm Motility / Q000502:physiology; D013084:Sperm-Ovum Interactions / Q000502:physiology