Intrafollicular insemination for the treatment of infertility in the dairy cow

Endoscopy-mediated intratubal insemination in the cow - Development of a novel minimally invasive AI technique

Conventionally inseminated spermatozoa suffer a dramatic reduction in numbers during their long journey until fertilization. In addition sperm survival seems to be strongly affected by the reconstitution of the female reproductive tract in the post partum period. The purpose of this study was to develop a novel AI technique for cattle that allows the deposition of spermatozoa directly into the ampulla in the immediate vicinity of the fertilization site. This new reproductive biotechnique was investigated with focus on semen origin, sperm dosage, semen preparation and time of insemination. Finally, a first practical application was carried out by inseminating superovulated heifers with sex-sorted semen. In total, 49 Simmental heifers were used for 65 intratubal inseminations (ITI) with single ovulation and 8 ITIs after superovulation, respectively. Insemination into the oviduct was performed under epidural anesthesia via transvaginal endoscopy using a curved glass capillary loaded with semen. Two days later the oviduct and the adjacent uterine horn were endoscopically flushed and embryos or unfertilized oocytes were collected for determination of fertilization success. Across all experimental groups, tubal insemination successfully resulted in the collection of embryos; however, first tubal AI attempts and ITIs close to ovulation led to low recovery rates. In total, 109 complexes were flushed from ITIs in superstimulated heifers (n = 8) using sex sorted semen, of which 24 (22%) were at the embryo stage. In conclusion, it was shown that intratubal insemination can be successfully used for semen deposition, thus bypassing the lower female genital tract. Factors such as time of insemination, semen processing and semen quantity for superovulatory use should be further investigated.

Reproductive management in dairy cows - the future

Background

Drivers of change in dairy herd health management include the significant increase in herd/farm size, quota removal (within Europe) and the increase in technologies to aid in dairy cow reproductive management.

Main body

There are a number of key areas for improving fertility management these include: i) handling of substantial volumes of data, ii) genetic selection (including improved phenotypes for use in breeding programmes), iii) nutritional management (including transition cow management), iv) control of infectious disease, v) reproductive management (and automated systems to improve reproductive management), vi) ovulation / oestrous synchronisation, vii) rapid diagnostics of reproductive status, and viii) management of male fertility. This review covers the current status and future outlook of many of these key factors that contribute to dairy cow herd health and reproductive performance.

Conclusions

In addition to improvements in genetic trends for fertility, numerous other future developments are likely in the near future. These include: i) development of new and novel fertility phenotypes that may be measurable in milk; ii) specific fertility genomic markers; iii) earlier and rapid pregnancy detection; iv) increased use of activity monitors; v) improved breeding protocols; vi) automated inline sensors for relevant phenotypes that become more affordable for farmers; and vii) capturing and mining multiple sources of “Big Data” available to dairy farmers. These should facilitate improved performance, health and fertility of dairy cows in the future.

Puncture and drainage of the subordinate follicles at timed artificial insemination prevents the risk of twin pregnancy in dairy cows

The objective of this study was to determine whether fluid drainage from the subordinate follicles by ovum pickup procedures prevents the risk of twin pregnancy without reducing the fertility of the cow. Lactating dairy cows with at least two follicles over 12 mm diameter located one on each ovary and selected from synchronized groups for fixed-time insemination were assigned to a Control (n = 49) or Drainage (n = 49) group. The largest follicle was considered as the dominant follicle. Draining of all subordinate follicles (≥10 mm) was performed in the Drainage group. All drained follicles developed as a corpus luteum 7 days later. In the Control cows, the presence of two corpora lutea (55.1%) was lower (p = .003) than those in the Drainage cows (87.8%), whereas the incidence of twin pregnancies was 50% and 0% for the Control and Drainage groups, respectively (p < .001). Draining did not affect the pregnancy rate. These results indicate that puncture and drainage of the subordinate follicles at insemination may eliminate the risk of twin pregnancies and reduce the risk of subsequent pregnancy loss by increasing the incidence of additional corpora lutea.

Temperature gradients in vivo influence maturing male and female gametes in mammals: evidence from the cow

Since 1980 several reports have indicated that temperatures vary between preovulatory follicles and other ovarian tissues in rabbit, cow, pig and human. However, these observations did not achieve prominence; they were regarded as artefacts due to the use of anaesthetics and open surgery (laparotomy). Recently, without resorting to anaesthesia or surgery, direct measurements of temperature in preovulatory follicles have been performed in the cow by means of a thermistor probe introduced into the antrum under ultrasonic guidance. Such follicles revealed a mean antral (follicular fluid) temperature 0.74°C and 1.54°C cooler than uterine surface and rectal temperatures respectively in ovulating cows, whereas no such temperature differences were detected in non-ovulating cows. Cows are predominantly monovular and preovulatory follicles attain a diameter of 15–22 mm or more. These features and the timescale of response to the preovulatory gonadotrophin surge make them a valuable model for the human preovulatory follicle. Temperature gradients are interpreted primarily in a context of final maturation of gametes immediately before the onset of fertilisation. Preovulatory follicular temperature in women could be assessed by a comparable approach and might become a valuable selection guide for oocyte viability.

Biomedical applications of ovarian transvaginal ultrasonography in cattle

Ovarian transvaginal ultrasonography (OTU) has been used world-wide for commercial ovum pick-up programs for in vitro embryo production in elite herds, providing an excellent model for the elucidation of factors controlling bovine oocyte developmental competence. Noninvasive sampling and treatment of ovarian structures is easily accomplished with bovine OTU techniques providing a promising system for in vivo delivery of transgenes directly into the ovary. The current review summarizes existing bovine OTU models and provides prospective applications of bovine OTU to undertake research in reproductive topics of biomedical relevance, with special emphasis on the development of in vivo gene transfer strategies.

Determination of minimum effective doses of luteinizing hormone and human chorionic gonadotropin for intrafollicular treatment to induce ovulation in dairy heifers

The aim of this study was to determine the minimum effective intrafollicular doses of luteinizing hormone and human chorionic gonadotropin in order to induce ovulation in cycling dairy heifers that have not yet been adequately established. Application of 10, 5, 1, 0.5, 0.1, 0.01 and 0.001 µg luteinizing hormone as well as 10, 1, 0.1, 0.01 and 0.001 international units (IU) of human chorionic gonadotropin in dominant follicles was performed on day 7 of the oestrous cycle. Control animals were given luteinizing hormone (12.5 mg and 25 mg) or human chorionic gonadotropin (2000 IU) intravenously. Accessory corpus luteum on day 14 of the oestrous cycle was considered as an evidence of ovulation. Ovulation was observed in 2 out of 3 heifers in each treatment group (n = 3) after administration of 10–0.1 µg luteinizing hormone (except for 0.5 µg – ovulation in 3 of 3 heifers), in all heifers after administration of 10–0.01 IU human chorionic gonadotropin as well as in all control heifers. Administration of 0.01 µg and 0.001 µg luteinizing hormone as well as of 0.001 IU human chorionic gonadotropin did not result in ovulation. Higher progesterone concentration on day 14 vs. day 7 of the oestrous cycle was found after all treatments. Nevertheless, the differences were significant (P < 0.05) only after intrafollicular treatments with 5, 1 and 0.001 µg luteinizing hormone as well as 10, 1 and 0.01 IU human chorionic gonadotropin. In conclusion, minimum efficient doses for intrafollicular treatment of the dominant follicles in cycling heifers capable of inducing ovulation were 0.1 µg of luteinizing hormone and 0.01 IU of human chorionic gonadotropin. This is the first study describing the intrafollicular luteinizing hormone administration in cycling dairy heifers.