Bull Biosecurity: Diagnosing Pathogens That Cause Infertility of Bulls or Transmission Via Semen

Introduction

Introduction of novel genetics to improve the performance of cattle herds is most commonly and efficiently achieved through introduction of new sires. Unfortunately, the introduction of new sires via natural breeding or artificial insemination has the potential to introduce pathogens that may result in infertility or subfertility and transmit disease causing agents to naive cows or heifers that may exhibit additional morbidity or mortality. Pathogens that should receive consideration when introducing new bulls in the United States include Brucella abortus, Campylobacter fetus, Histophilus somni, Leptospira species, Mycobacterium bovis, Mycobacterium avium subsp. paratuberculosis, Tritrichomonas foetus, bovine viral diarrhea virus, bluetongue virus, infectious bovine rhinotracheitis virus (bovine herpesvirus- 1), and bovine herpesvirus-5. When obtaining bulls or semen from outside of the United States, biosecurity measures to prevent introduction of foot-and-mouth disease, rinderpest, lumpy skin disease, and Rift Valley fever viruses should also be considered.
Prudent use of resources may dictate that new bulls are only tested for some of these pathogens due to (a) low prevalence or total lack of the pathogen in the herd from which the bull originated, (b) a high likelihood that the pathogen is already present in the herd to which the bull will be introduced, (c) the lack of diagnostic sensitivity of available assays to detect particular pathogens in bulls, and (d) the time between when the owner first has access to diagnostic samples from the bull and when the bull needs to be introduced to optimize reproduction of the herd. [...]