Peer-reviewed veterinary case report
How to choose cattle resistant to Rhipicephalus microplus ticks?
By Simões MRS et al.·2026·Graduate Program in Animal Science - Federal University of Pelotas (UFPEL), Brazil·View original on Europe PMC →
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Original publication title: Polygenic control of Rhipicephalus microplus infestation in purebred and crossbred cattle revealed by GWAS.
- Species:
- cattle
Plain-English summary
This study looked at how different breeds of cattle in Brazil respond to tick infestations, which are a major problem for cattle health and productivity. Researchers found that Nellore cattle had the fewest ticks, while other breeds like Angus and Hereford had significantly more. They used advanced genetic analysis to identify specific areas in the cattle's DNA that might help in breeding animals that are more resistant to ticks. The findings suggest that using genetic information can help farmers choose cattle that are less likely to get infested with ticks. Overall, the research supports the idea that breeding for tick resistance is important and can be improved with genetic tools.
Abstract
Selecting cattle for enhanced resistance to ticks is essential for improving herd productivity and safeguarding animal welfare. In Brazilian production systems, tick resistance is a key factor influencing competitiveness in domestic and export-oriented beef chains. This study evaluated tick resistance in taurine and indicine cattle and their crossbreds in Rio Grande do Sul, a subtropical region where Rhipicephalus (Boophilus) microplus infestation is highly prevalent and represents the only tick species parasitizing cattle. Breed-group differences in tick counts were quantified, and the potential of genomic tools to support the selection of more resistant animals was assessed. A repeated-measures mixed model was used to compare mean tick loads and to estimate direct, maternal, and heterotic effects. Nellore cattle exhibited the lowest mean tick counts (1.00 ± 0.24), followed by Angus × Nellore (3.66 ± 0.57), Nellore × Angus (4.34 ± 0.55), Caracu × Angus (8.24 ± 0.78), Angus (10.28 ± 0.94), Angus × Hereford (12.44 ± 1.37), Hereford (12.61 ± 1.38), and Hereford × Angus (12.92 ± 1.18). Heritability and repeatability for tick infestation were 0.165 ± 0.03 and 0.179 ± 0.05, respectively. A genome-wide association study identified genomic regions on chromosomes 3, 4, 5, 16, and 22 associated with variation in tick load. Candidate genes within these regions were characterized using MeSH enrichment analyses. The results reinforce the polygenic basis of tick resistance and demonstrate the relevance of genomic information for improving selection strategies in both purebred and crossbred cattle populations.
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Search related cases →Original publication on Europe PMC: https://europepmc.org/article/MED/41831245