Artificial Insemination of Ewes with Ram Semen Frozen by the Pellet Method

Abstract

One problem encountered in the widespread application of sheep artificial insemination (AI) is the rapid decline in fertility of fresh or liquid chilled ram semen. An effective deep-freezing procedure would enable semen to be collected and stored from selected rams throughout the year for subsequent use in controlled breeding programmes, as well as facilitating the import and export of semen.Following some encouraging results from the use of pooled semen frozen by an Australian pellet method (Maxwell et al 1980), further field trials were conducted to investigate fertility of semen frozen from individual rams as well as pooled semen. The effects of season of freezing and number of inseminations on fertility were also investigated.

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

“…Although in these trials no ewes were inseminated with frozen-thawed semen via the cervical route, to permit a direct comparison with the intra-uterine technique, the overall conception rates achieved were as good as, and in many cases higher than, those reported in the literature following cervical insemination of frozen-thawed semen (Colas, 1979;Maxwell et al, 1980;Colas and Guerin, 1981;Curnock et al, 1984;Haresign et al, 1986;Fiser, Ainsworth and Fairfull, 1987). Furthermore, these better conception rates were achieved with much smaller semen volumes (motile sperm numbers), and as such illustrate that the technique can have a marked effect on increasing selection pressure through the male line.…”

“…The widespread use of artificial insemination in the United Kingdom (UK) sheep industry has been hampered by the poor conception rates obtained after cervical insemination of frozen-thawed semen (Dzuik, Lewis, Graham and Moyer, 1972;Langford, Marcus, Hackett, Ainsworth, Wolynetz and Peters, 1979;Maxwell, Curnock, Logue and Reed, 1980;Curnock, Reed, Logue and Maxwell, 1984). Although much higher conception rates can be achieved following cervical insemination of fresh-chilled semen (Meat and Livestock Commission (MLC), 1982;King, Clark, Fraser and Aitkin, 1984), the short shelf-life of fresh semen restricts the geographical movement of genes, a factor of considerable importance for sire referencing schemes.…”

A note on the use of laparoscopy for intrauterine insemination of frozen-thawed semen in the ewe

“…Several field trials have been conducted in the UK over a number of years to assess fertility of ewes synchronized with progestagen sponges and pregnant mare's serum gonadotropin (PMSG) to cervical insemination with frozen-thawed ram semen (Maxwell, Curnock, Logue and Reed, 1980;Curnock, Reed, Logue and Maxwell, 1984). Several field trials have been conducted in the UK over a number of years to assess fertility of ewes synchronized with progestagen sponges and pregnant mare's serum gonadotropin (PMSG) to cervical insemination with frozen-thawed ram semen (Maxwell, Curnock, Logue and Reed, 1980;Curnock, Reed, Logue and Maxwell, 1984).…”

“…Killeen and Caffery (1982) reported a rapid laparoscopic technique under local anaesthesia for depositing semen directly into the uterine lumen, and fertilization rates with frozen-thawed semen of 50% have been obtained using this intrauterine insemination method compared with 11% using the cervical insemination technique (Maxwell, Wilson and Butler, 1983). Indeed, their results suggested that intrauterine insemination of frozenthawed semen using laparoscopy may be as effective as cervical insemination of fresh semen (Maxwell, 1984).…”

“…Nevertheless, the lambing rate obtained with frozen-thawed semen deposited into the cervix was similar to previously reported figures (Visser and Salamon, 1974;Maxwell et al, 1980). Although several workers have reported increased embryo losses following uterine deposition of semen at laparotomy (Salamon and Lightfoot, 1967;Killeen and Moore, 1970), the limited amount of work reported using the laparoscopic method of insemination has found no adverse effects on the subsequent fertility of the ewes nor any increase in embryo mortality (Maxwell, 1984;McKelvey, Robinson, Aitken and Henderson, 1985). In addition, it seems probable that the 4/15 ewes in this treatment group which were diagnosed pregnant on day 19 by progesterone analysis, but which failed to lamb at the expected time, suffered late complete embryo loss, since none of them was observed to be in oestrus between 5 and 25 days after insemination.…”