The Fertility of Bovine Semen Cooled with and without the Addition of Citrate-Sulfanilamide-Yolk Extender

Summary Sixty-four ejaculates of bovine semen were divided and cooled from 30° C. to 5° C. in 75 minutes with and without the addition of citrate-sulfanilamide-yolk extender prior to cooling. Based on 60- to 90-day non-returns to 8,518 first and second service cows, the fertility level of the pre-extended semen (semen cooled in extender) was 59.3 per cent and that of the post-extended semen (cooled without extender), 52.8 per cent. The difference between treatments of 6.5 percentage units was highly-significant statistically. Motility estimates made after 3, 24, 48, 72 and 96 hr. of storage indicated that the samples cooled without extender had a definitely lower percentage of motile spermatozoa. However, by using covariance analysis the higher per cent non-returns for the pre-extended semen could not be accounted for on the basis of more motile spermatozoa per insemination.