title: Equine frozen semen: freezability and fertility field results.
abstract: The freezability of stallion semen defined as the number of selected ejaculates/total number of ejaculates frozen from 161 different stallions was analyzed. Of the stallions, 19, 30, 27 and 24% had a freezability of 0%, 0 to 33%, 33 to 66%, over 66%, respectively In 85 different stallions, the correlation of freezability between first and second year was 0.60 (P < 0.001). The relationship between fertility with fresh and frozen semen and freezability was analyzed in 40 stallions whose freezability and fertility information was recorded during 5 years. There was a strong relationship between fertility of fresh semen and semen freezability (P < 0.001). However, the relationship between fertility of frozen semen and freezability was not as marked (P < 0.05). Analysis of the field fertility per cycle results when mares were bred with 300 or 150 x 10(6) total spermatozoa at different frequencies until ovulation indicated that mares that were inseminated 2 times or more per estrus show an improved fertility in comparison with mares inseminated only once (34%, n = 1576 vs 26%, n = 626; P < 0.001). Foaling rate when mares were inseminated with frozen semen (1858 mares during 8 breeding seasons) was mainly influenced by mare age (< 16 years: 54% vs >/= 16 years 42% p < 0.001). Date of first insemination (before May 15: 58% vs after May 15: 37%) also had a significant effect on foaling rate (P < 0.001).
authors.affiliation: Horse Institute, National Studs and I.N.R.A. 37380 Nouzilly, France.
authors.forename: M
authors.initials: M
authors.lastname: Vidament
authors.forename: A M
authors.initials: AM
authors.lastname: Dupere
authors.forename: P
authors.initials: P
authors.lastname: Julienne
authors.forename: A
authors.initials: A
authors.lastname: Evain
authors.forename: P
authors.initials: P
authors.lastname: Noue
authors.forename: E
authors.initials: E
authors.lastname: Palmer