Pregnancy rates in heifers and cows with cryopreserved sexed sperm: effects of sperm numbers per inseminate, sorting pressure and sperm storage before sorting.

摘要: Abstract Field trials were conducted to increase fertility with AI of flow-sorted, sexed bovine sperm. In the first trial, a novel competitive fertilization approach was used compare pressures (30 psi vs 50 psi) for sorting Both X- and Y-sperm sorted approximately 95% purity at 30 50 psi; X-50 + Y-30 (and converse) mixed in equal numbers heifers. Fetal sex divulged which treatment produced pregnancy; 82% pregnancies resulted from 30 psi (P   0.1). Lactating dairy cows pre-screened normal reproductive tracts when OvSynch injections (GnRH, prostaglandin, GnRH) initiated, had similar (P > 0.1) pregnancy rates timed AI, 10 × 106 sperm (43.9%, n = 57), 2 × 106 (40.5%, n = 57) unsexed control (55.6%, n = 58). A final field trial unselected, lactating 0.25 mL straws (25.0%, n = 708) 0.5 mL (24.4%, n = 776), but lower 84 days milk highest both These studies improved sexing procedures, provided insight into appropriate commercial use