The Effect of Whole Ejaculate Filtration on the Morphology and the Fertility of Bovine Semen

A Sephadex G-15 filtration method was developed to remove abnormal and nonmotile bull sperm from an entire ejaculate. The efficiency of filtration was determined by adding freeze-killed sperm to the ejaculate or using ejaculates with elevated numbers of abnormal cells induced by scrotal insulation. A fertility trial, using split ejaculates, compared fertility of filtered and unfiltered semen. After filtration, samples with 0, 25, and 50% killed cells added contained 77 to 81% motile cells. Addition of 75% killed sperm resulted in significant decrease (52%) of motile cells following filtration. Morphologic examination of semen with elevated numbers of abnormal cells revealed higher percentages of sperm with normal shaped heads and normal or swollen acrosomes after filtration than in unfiltered samples. Percentage of pear-shaped heads, lifted acrosomes, and bent tails decreased after filtration. Six high fertility and six low fertility bulls were used to evaluate fertility of filtered semen. Filtering increased motile sperm from 51 to 57% and from 36 to 50% for the high and low fertility bulls, respectively. The 60- to 90-d nonreturn rates for high fertility bulls were not increased by filtering (73 vs. 72%). However, filtering significantly improved the nonreturn rates for the low fertility bulls (61 vs. 67%).