title: Comparison of fertility results after vaginal insemination using different thawing procedures and packages for frozen ram semen.
abstract: BACKGROUND
  The effect of different thawing procedures for ram semen frozen in minitubes and mini straws on the fertility of sheep was tested in a field trial.
  
  
  METHODS
  Altogether, 719 Norwegian Crossbred ewes, aged between six months and six-and-a-half years from 8 farms, were inseminated vaginally in natural oestrus with frozen-thawed semen. Minitubes were thawed at 70 degrees C for 8 sec (T70) and mini straws either at 50 degrees C for 9 sec (S50) or at 35 degrees C for 12 sec (S35).
  
  
  RESULTS
  Vaginal insemination with 200 x 106 spermatozoa resulted in 25-days non-return rates of 63.2, 59.6, and 62.5% (overall 61.8%), respectively, and lambing rates of 56.8, 55.0, and 59.2% (overall 57.0%), respectively. No significant effect on fertility (as 25-days non-return- or lambing rate) was seen for straw type/thawing temperature (P = 0.5/0.5), but semen filled in mini straws and thawed at 35 degrees C resulted numerically in the highest lambing rate (59.2%). A significant effect was, however, seen for farmer (P = >0.0001/>0.0001) and ram (P = 0.009/0.002). Moreover, age of the ewes had a significant effect on the NR rate (0.007), but not on lambing rate (P = 0.2).
  
  
  CONCLUSIONS
  A vaginal deposition of frozen ram semen containing approximately 200 x 106 spermatozoa, filled in mini straws and thawed at 35 degrees C is a simplified technique that under field conditions and used on a do-it-yourself regime gives acceptable lambing rates in Norway.
authors: Norwegian School of Veterinary Science, PO Box 8146 Dep., N-0033 Oslo, Norway. heiko.paulenz@veths.no
authors: Heiko
authors: H
authors: Paulenz
authors: Tormod
authors: T
authors: Adnøy
authors: Lennart
authors: L
authors: Söderquist
mesh_terms: D000367:Age Factors; D000818:Animals; D015925:Cryopreservation / Q000662:veterinary*; D005260:Female; D005298:Fertility / Q000502:physiology*; D007315:Insemination, Artificial / Q000662:veterinary; D008297:Male; D011247:Pregnancy; D011256:Pregnancy Outcome; D012661:Semen / Q000502:physiology*; D012662:Semen Preservation / Q000662:veterinary*; D012756:Sheep / Q000502:physiology*; D013696:Temperature; D014621:Vagina / Q000502:physiology