title: Fertility of frozen-thawed porcine semen following controlled-rate freezing in straws.
abstract: A method was developed for freezing large batches of porcine semen in straws at a controlled rate in a liquid nitrogen programmable freezer. The fertilizing potential of spermatozoa frozen by this method was examined by inseminating 220 sows with a mixture of semen from two boars. Estrus was synchronized using one of two regimens and sows were inseminated once at 34 h after human chorionic gonadotropin (hCG) treatment. The average pregnancy rate at 60 d of gestation, farrowing rate and litter size were 60.9%, 51.4% and 8.8, respectively. The fertilizing potential of spermatozoa frozen by this method appeared to be similar to that reported for other methods of freezing porcine semen.
authors.affiliation: Department of Veterinary Physiology, Iowa State University, Ames, IA 50011 USA.
authors.forename: D G
authors.initials: DG
authors.lastname: Hammitt
authors.forename: P A
authors.initials: PA
authors.lastname: Martin