Correlations and repeatability between Babesia spp. infection levels using two dairy cattle breeding systems

Area of Science:

• Veterinary Parasitology
• Animal Genetics
• Molecular Diagnostics

Background:

• Babesia bovis and Babesia bigemina are significant tick-borne pathogens impacting global livestock.
• Previous research indicates breed and individual variations in cattle resistance to babesiosis.
• Understanding infection dynamics is crucial for managing livestock health and economic losses.

Purpose of the Study:

• To evaluate the repeatability and correlation of Babesia bovis and Babesia bigemina infection levels.
• To compare these parameters between individual (IS) and collective paddock (CPS) cattle breeding systems.
• To explore potential links between breeding systems, host resistance, and parasite dynamics.

Main Methods:

• Quantitative polymerase chain reaction (qPCR) was used to quantify B. bovis and B. bigemina DNA in blood samples.
• Holstein cattle were studied under two distinct breeding systems: individual (IS) and collective paddock (CPS).
• Statistical analyses were performed to estimate correlation and repeatability coefficients for parasite loads.

Main Results:

• Moderate correlations were observed for B. bigemina and high correlations for B. bovis DNA copy numbers between systems.
• Repeatability estimates for both Babesia species were moderate across both IS and CPS.
• High variability in resistance/susceptibility among cattle was confirmed, influencing parasite correlations.

Conclusions:

• High correlations between B. bovis and B. bigemina infection levels suggest that measuring one can predict the other.
• Breeding systems and inherent cattle resistance likely contribute to observed infection patterns and repeatability.
• Findings support the potential for genetic selection related to resistance against multiple Babesia species in cattle.