A. Kumaresan Laboratory

Theriogenology Lab welcomes you!

Although male and female contributes almost equally to infertility, male fertility assume significance in dairy animals because semen from a single male is used to artificially breed several thousands of females. Using semen from an infertile/sub-fertile bull to breed cows results in reduced conception rates and fewer number of calves born during the reproductive lifetime of the cows, which ultimately lead to reduced replacement heifers and colossal loss to the farmers.

Subfertility/infertility is a major problem in crossbred bulls (offspring produced by mating Bos taurus males with Bos indicus females) as compared to purebred. Due to poor fertility more than 50% of crossbred bulls, which were progenies of best dams and confirmed sires, were removed from the breeding programs. Earlier findings indicate that the incidence of poor semen quality ejaculates ranged from 23 to 100%, with an average of 52%. The reason behind high incidence of infertility/sub-fertility and poor quality of semen in crossbred bulls, however, is not well defined yet.

Breeding bulls are generally selected based on Breeding Soundness Evaluation (BSE) that assess the physical fitness, mating and semen production abilities of the bulls. Although, BSE helps in preliminary bull selection, it does not provide information about the fertility status. Around 20 to 25% differences in conception rates were observed among the breeding bulls selected after thorough breeding soundness evaluation. These inferior bulls can be identified at a very later stage only, upon large scale use of semen samples through artificial insemination and subsequent feedback from the field, substantially hampering the genetic gain.

Theriogenology lab is working to understand the reason for higher incidence of infertility in crossbred bulls and to develop tools/methods for prediction of future fertility of a male at young age. The research at our lab is primarily focused on understanding the phenotypic, functional and molecular differences between spermatozoa from high- and low-fertile bulls.  In this direction, we identified the subtle phenotypic and functional differences between spermatozoa from fertile and sub-fertile breeding bulls and developed fertility prediction equations for Holstein Friesian purebred, Holstein Friesian crossbred, Jersey crossbred and Murrah buffalo bulls. These equations can be helpful to frozen semen stations in ensuring quality and fertility of frozen semen doses used for artificial breeding. Also, we identified potential fertility associated sperm and seminal plasma proteins in crossbred bulls and are in the process of translating them into technologies for bull fertility prediction. We proved that the quantity and quality of Sertoli cells in a given male is related to his fertility.

Currently, our lab is engaged in deciphering the alterations in low-fertile crossbred bulls at testicular and semen level. We hypothesize that identifying the molecular alterations in spermatozoa from infertile/sub-fertile bulls would facilitate us to understand the etiology behind the infertility. We use multi “OMICS” approach to understand the differences between fertile and infertile/sub-fertile males and to identify potential fertility associated molecules for development of bull fertility prediction assay/tests/methods.