• Gamete intrafallopian transfer (GIFT) is the surgical deposition of a donor mare oocyte and spermatozoa into the fallopian tube (oviduct) of a recipient mare.
• GIFT differs from oocyte transfer Reproduction: oocyte transfer. In oocyte transfer the donor mare oocyte is placed in the oviduct of a recipient mare, and the recipient is inseminated by deposition of semen into the uterus. Whereas, in GIFT both the oocyte and spermatozoa are placed directly into the recipient mare’s fallopian tube (oviduct) for in vivo fertilization, with subsequent embryonic and fetal development occurring in the recipient mare.

Uses

• Oocyte donation Reproduction: oocyte collection followed by oocyte transfer Reproduction: oocyte transfer is a useful technique in obtaining pregnancies from mares whose subfertility is attributable to some cause other than poor oocyte quality.
• However, oocyte donation and transfer is used in conjunction with conventional artificial insemination techniques, and its success therefore relies partly on the semen being of good quality.
• Because GIFT involves the deposition of both oocyte and spermatozoa in the fallopian tube (oviduct) near the site of fertilization, sperm cells do not have to successfully navigate from the uterus, through the utero-tubal junction, into the fallopian tube (oviduct). GIFT is therefore a more useful technique than oocyte transfer alone when either the quality of the semen is poor, or sperm numbers are low (for example when only small quantities of either frozen semen or sex-sorted sperm cells are available).

Advantages

• Provides a method of achieving pregnancies in cases of combined mare subfertility (due to a factor other than oocyte quality) and poor semen quality / limited sperm numbers.
• This is useful since whereas in other species in vitro fertilization is often used to overcome such cases of combined female:male subfertility, in horses, in vitro fertilization is comparatively unsuccessful.
• GIFT is useful in mares which suffer from post-mating induced endometritis due to poor clearance of uterine fluid.

Disadvantages

• Very variable success rates.
• Poor pregnancy rates associated with the use of chilled and frozen semen.

Technical problems

• Problems with oocyte maturation and transfer Reproduction: oocyte transfer.
• Need to process semen to remove seminal plasma, debris and contamination (see below) and to select fertile sperm (see below).
• Lower success rates are currently achieved using chilled and frozen semen (which are likely to be used commonly in practice) than using freshly collected semen.

Alternative techniques

• Intracytoplasmic sperm injection.