Recent advances in equine artificial insemination using frozen semen have resulted in conception rates near to those of live-cover and fresh-cooled breeding methods. Deep uterine insemination is a useful new technique. It was originally developed to help increase the chances for conception when using the semen of sub-fertile stallions, and when using low numbers of sperm, which is why it is also called “low-dose” insemination. When done properly deep uterine insemination can decrease the amount of semen used per insemination, while also increasing conception rates.
Why use deep uterine insemination?
- Increase the number of mares bred per ejaculate
- Utilize stallions with poor semen quality
- Extend the use of frozen semen
- Breed mares with sex-sorted semen
- Possibly reduce the incidence of post-breeding endometritis
What is deep uterine insemination?
- Deep uterine insemination is the placing of sperm at the junction where the fallopian tube enters the uterus, the uterotubal junction. Before insemination, sperm which have been collected, processed and mixed with extender and frozen, are thawed and centrifuged to reduce volume or to be sex-sorted. The resultant small amount of sperm is aspirated into a catheter attached to a 2.5 ml. syringe. The loaded catheter is then withdrawn into an outer plastic cannula, which is passed down the working channel of a videoendoscope (camera). The flexible endoscope is guided through the cervix and propelled forward through the uterus of the mare by the operator’s sterile gloved arm in the vagina, with the aid of ultrasound or manipulated rectally into position. The endoscope is directed along the uterine horn ispsilateral to the ovary containing a pre-ovulatory follicle of 35 mm diameter. When the tip of the catheter containing the sperm suspension touches the papilla of the uterotubal junction, the plunger of the syringe is depressed to deposit the small amount of frothy semen suspension on the surface of the papilla. The endoscope is then withdrawn while simultaneously evacuating the filtered air that was previously introduced to facilitate passage of the instrument through the uterus.
Results from several different studies have shown that low-dose or deep uterine insemination produces consistent results. The following number of sperm per insemination resulted in conception rates of:
- 1.0 million sperm = 64% conception
- 5.0 million sperm = 75% conception
- 10.0 million sperm = 60% conception
These percentages were fairly consistent within several different studies.
- How is semen sex-sorted?
Sex-sorting of semen was the original reason for using deep uterine insemination. Because the process of sorting a dose of semen by sex chromosomes takes about an hour, the semen must be used in small amounts, before it becomes too old. This limitation would preclude its use in insemination with conventional high numbers of sperm per dose.