Evaluation of intrauterine insemination of sheep with frozen semen: effects of time of insemination and semen dose on conception rates

Abstract

The field application of a laparoscopic technique to permit intra-uterine insemination of ewes with frozen-thawed semen was examined in two trials, conducted over successive years, to (i) determine the optimum time of insemination relative to sponge removal/pregnant mares's serum gonadotropin (PMSG) injection and (ii) establish the relationship between semen dose and conception rate. Pooled semen was used in both trials, and each involved > 900 ewes in a number of commercial flocks. Maximum conception rates were achieved when insemination was conducted between 54 h and 60 h after sponge removal/ PMSG injection. However, there was no significant difference in conception rate when motile sperm numbers were reduced from 52-2 X 10 6 to 13-0 X 10 6 motile sperm per uterine horn. The overall conception rates (pooled over flocks and treatment groups) were 56% and 58% for the two trials, with a wide degree of variation between flocks in both cases (45% to 79% for trial 1 and 45% to 69% for trial 2). However, there was evidence for consistent differences in conception rates between the six flocks involved in both years of the trials.

Pregnancy and Lambing Rate Following Laparoscopic Artificial Insemination with Two Different Types of Diluent and Frozen-thawed Sperm Dose in Ewes

“…Evans and Maxwell (1987) found that 20 × 10 6 motile spermatozoa suffice for achieving a high pregnancy rate, while Eppleston et al (1986) and Salamon et al (1985) reported high fertility rate after insemination with 5 × 10 6 and 10 × l0 6 motile spermatozoa, respectively. Findlater et al (1991) reported similar results with 13 × l0 6 motile sperm cells per uterine horn. Factors such as age, parity, lactation status, and body condition of the ewe could influence fertility rate (Anel et al, 2005;Fukui et al, 2010;Palacin et al, 2012) (Downing and Scaramuzzi, 1991).…”

Production of New Kenguri Strain-1 of Sheep by Breeding with Nari-Suwarna Frozen Thawed Semen

“…This is consistent with the findings of others (Findlater 1991;Maxwell and Watson, 1996) and the proportion of progressively motile cells is reduced by the processes of cooling, freezing and thawing (Haresign, 1990;Maxwell and Watson, 1996), resulting in impaired ability to penetrate the cervix. However, the conception rate with frozen -thawed semen in the present study is lower i.e.…”

Intervals from norgestomet withdrawal and injection of equine chorionic gonadotropin or P.G. 600 to estrus and ovulation in ewes.

“…However, the variation among studies in the intervals after progestogen withdrawal and eCG treatment to estrus and to ovulation has made it difficult to settle on a specific time for AI with frozen-thawed semen. Despite that, acceptable fertilization (up to 95%; Jabbour and Evans, 1991;Maxwell et al, 1993) and pregnancy rates (up to 80%; Fukui et al, 1989;Findlater et al, 1991;Husein et al, 1996) are possible after AI during a rather large time frame of 42 to 60 h after progestogen withdrawal and eCG treatment, and this generally encompasses the interval from approximately 24 h before until approximately 5 h after ovulation, although this relationship also varies a good deal among studies. Even though a "best" time for AI with frozen-thawed semen has not been identified, collectively the studies support the idea that sperm should spend enough time in the female reproductive tract to become capacitated and capable of fertilization, without becoming aged.…”