LBTU Research Completed: First Results Achieved in Sex-Sorting of Bull Sperm Using Innovative Technology

Nearly three years ago, LBTU, as the lead partner, began work on the project under the guidance of Dr. Ilga Sematovica, Associate Professor at the Clinical Institute of the Faculty of Veterinary Medicine.The project involved several partners, including the Biochip Scientific Laboratory of Riga Technical University (RTU), the Kurzeme Pedigree and Artificial Insemination Station, (AS "Dimedium Latvia" as of January 1, 2024), the Sigulda Pedigree and Artificial Insemination Station (AS "Siguldas CMAS"), and SIA "Griezes Lejnieki".

Since 2017, the Faculty of Veterinary Medicine has been developing the field of veterinary assisted reproduction technologies (VetART) in Latvia, enabling the implementation of various projects. During this time, an embryo transfer laboratory was created and improved to support extensive research with gametes and the acquisition and development of embryos.

A major milestone in animal reproduction and livestock development was the introduction of artificial insemination in the 1970s. Since then, other reproductive biotechnologies have been developed, such as multiple ovulation and embryo transfer, and ovum pick-up with in vitro fertilization, which are all part of ART methods. VetART aims to promote faster and higher-quality herd renewal using genetically valuable and healthy animals.

The project's main goal was to determine whether bull sperm sex-sorting could be performed in Latvia to predict the offspring's sex based on genetic information. Globally, the market for sex-sorted bull sperm is relatively monopolized, which drives up the product’s cost.

As project leader Dr. Ilga Sematovica explains: "One of the biggest challenges was finding and adapting the necessary equipment for the sex-sorting process. Sperm cells are ‘living’ cells and are highly sensitive to various environmental factors—changes in temperature, humidity, or atmospheric pressure can negatively affect their viability. Viability is assessed through various parameters, with motility being the key factor for successful fertilization. Therefore, any interference with the physiological processes of the cells can endanger the outcome."

"At first, RTU’s Biochip Scientific Laboratory managed to sort only a few dozen sperm cells, later increasing to a few thousand, but this volume was still insufficient for successful fertilization. Moreover, the sorting process itself, as seen in global monopoly companies, negatively affects sperm viability and fertilization capacity. Although the project stalled temporarily while seeking optimal solutions, the goal was ultimately achieved—we obtained pregnancies with offspring of the desired sex. Each sperm dose contained a sufficient number (millions) of viable sperm. This marked the first time bull sperm sex-sorting was performed in Latvia, and the resulting biomaterial was of sufficient quality—sometimes even superior to commercially available options."

Although the successful outcome was achieved couple of months before the end of the project, five pregnancies were obtained using artificial insemination with sex-sorted and deep-frozen bull sperm from laboratory of RTU. Three pregnancies were also achieved using embryos grown in the LBTU Faculty of Veterinary Medicine VetART laboratory.

Regarding the quality of sex-sorting, commercial sperm doses are considered acceptable even if up to 10% of the offspring are of the undesired sex. RTU performed special analyses to verify the quality of its sex-sorting process. However, the exact result can only be confirmed after about 285 days (the length of cow gestation), when the calf is born. To determine the sex earlier, Dr. Sematovica, together with veterinarian Eriks Bite, learned how to determine fetal sex in pregnant cows transrectally using ultrasonography. This test can be performed in early pregnancy, approximately between the 55th and the 70th day. This is a significant advancement in the practical application of veterinary reproduction.

By doing, we improve—this project has opened a new field of innovation for future work and collaboration with interested parties, which we aim to pursue further.