More than 95% of beef farms in the US rely on natural mating as their main breeding system. For this reason, the bull is the individual within a herd that bears the major responsibility on the overall herd fertility, as one single bull can potentially sire between 25 to 60 cows in one breeding season. At present we have no single parameter that allows us to predict potential daily sperm production in individual bulls. Sertoli cells (SC) are those cells within the testis responsible for nourishing and providing the necessary physical support to sustain germ cells throughout the process of spermatogenesis, from spermatogonia to spermatozoa. Sertoli cells replicate at a specific window of time during the fetal and neonatal stages in the bull. It has been determined that the final size of the SC population established before puberty is one of the most important factors determining the potential daily sperm production in the bull. Two main lines of research have been established: one is the development of low invasiveness techniques to determine the size of the SC established in the testis before puberty. The other is the development of interventions from the fetal to the pubertal stage in the bull to increase SC replication and the final size of the cell population established in the bull testis, thereby increasing the potential daily sperm production.
The two projects are being developed through a collaboration I established between NC State Animal Sciences Department, the Pathology Services Core at the Lineberger Comprehensive Cancer Center at the UNC School of Medicine (Chapel Hill), and the Biotechnology Research and Training Center at UNCP. NC State has provided the animals and the infrastructure needed at their Upper Piedmont Research Station in Reidsville, NC, and it will be performing the IGF-1 concentration determination in serum. On the other side, the University of North Carolina at Chapel Hill will be providing the histology services. Once the tissues are processed, Sertoli and germ cell counts will be done at the biotech research center here at UNCP. The testicles were collected from those bulls that were not eligible for sale, so after the research station selected the bulls for their own replacements and those destined for their annual sale, we chose from the remaining animals -- our bulls.
I would like to mention especially the disposition and support provided by my two main collaborators: Dr. Daniel Poole (Associate Professor of Reproductive Physiology, Animal Sciences, NCSU) and Dr. Joseph French (Research Operations Manager at Upper Piedmont Research Station, NCSU). The two projects (“The use of Fine Needle Aspiration and Immunohistochemistry to Determine the Size of the Sertoli Cell Population,” and “The Effect of IGF1 on Testicular Growth and Development in Prepubertal Beef Bulls”) are possible through two UNCP internal grants: The Dean’s Research Grant and the Faculty Summer Research Grant. Three undergraduate students are directly involved in all stages of the project: Kalani Gaddy (RISE), Sidney Clayman (RISE), and Sydney Allen (research student). They have been participating in the BST administration, records, scrotal circumference measurements, blood sampling, surgical castration, and tissue collection.
Article written by Dr. Nico Negrin Pereira
Web manager’s note: Dr. Negrin Pereira, one of the newest members of the Biology faculty, teaches undergraduate courses in agricultural science, including Introduction to Animal Science and Principles of Animal Nutrition, and he will teach Animal Reproductive Physiology in the fall. He was honored last fall during the UNCP volleyball team’s Faculty and Staff Appreciation night for making a positive impact on the life of a student athlete.
