Sexing Livestock Sperm by Flow Cytometry - Biology, Technology and Present State

P. PENCHEV
Agricultural Institute, BG-9700 Shumen, Bulgaria

Abstract

PENCHEV, P., 2005. Sexing livestock sperm by flow cytometry - biology, technology, and present state. Bulg. J. Agric. Sci., 11: 227-241

For several years it is possible through flow cytometry to sort X- and Y-spermatozoa on the base of the difference in their total DNA content, ranging from 3.5 to 4.4% for the main livestock species. The capacity of the commercially used sorters is 5,000 live bovine sperm of each sex per second at 85-95% accuracy. About 88% of the processed sperm are discarded or lost after all stages of sorting.
Thousands of offspring have officially resulted from sperm sexing technology in domestic animals (primarily in cattle) and humans, and none has shown abnormal growth; laser emission, DNA-binding dyes, and high fluidic pressure affect significantly the fertility of the sperm only, and this reflects on the lowered by 20 to 40% pregnancy rates.
Artificial insemination (AI) with doses of about 2x106 sexed, cryopreserved semen is being applied commercially to cattle in some countries, while additional operations like in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), endoscopy, or laparotomy are indispensable with horses, pigs, and sheep.

Sperm sexing technology in dairy cattle would bring considerable increase in genetic gain and decrease in incidence of dystocia.

Key words: flow cytometry, fluorescence, DNA, sexing, X- and Y-spermatozoa, Hoechst 33342, droplet sorter
Abbreviations: AI - artificial insemination; IVF - in vitro fertilization; ICSI - intracytoplasmic sperm injection British-American units: psi - pounds per square inch, 1 psi ~ 72 g/cm2