Detection of genetic variability in dairy cattle infectivity for bovine tuberculosis
ABSTRACT: This study investigated the genetics of bovine tuberculosis (bTB) infectivity in Holstein-Friesian dairy cows using British national data. The analyses included cows with recorded sires from herds affected by bTB outbreaks between 2000 and 2022. Animals were considered bTB positive if they...
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Elsevier
2025-04-01
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| Series: | Journal of Dairy Science |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S0022030224014413 |
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| author | D. Madenci E. Sánchez-Molano M. Winters A. Mitchell M.P. Coffey J.D. Hadfield J.A. Woolliams G. Banos A. Doeschl-Wilson |
| author_facet | D. Madenci E. Sánchez-Molano M. Winters A. Mitchell M.P. Coffey J.D. Hadfield J.A. Woolliams G. Banos A. Doeschl-Wilson |
| author_sort | D. Madenci |
| collection | DOAJ |
| description | ABSTRACT: This study investigated the genetics of bovine tuberculosis (bTB) infectivity in Holstein-Friesian dairy cows using British national data. The analyses included cows with recorded sires from herds affected by bTB outbreaks between 2000 and 2022. Animals were considered bTB positive if they reacted positively to the skin test, had positive postmortem findings, or both. We introduced the “index case approach,” based on the assumption that once the initial positively tested animals (index cases) are detected in a herd, subsequent infections (secondary cases) in the early stages of the breakdown are likely to be attributed to these animals. Genetic analysis of the number of secondary cases (NrSC) associated with a given index case was used to establish evidence of genetic variability in bTB infectivity of cattle, and derive EBV for infectivity for the sires of the index cases. Data were analyzed by employing Markov chain Monte Carlo techniques to fit generalized linear mixed models with either Poisson, zero-inflated Poisson (ZIP), hurdle Poisson, or geometric distributions. All 4 models demonstrated presence of genetic variance in cattle infectivity, with the strongest evidence provided by the ZIP and hurdle Poisson models. The hurdle Poisson model offered the most accurate and least biased predictions. Sire infectivity EBV from the Poisson, ZIP, and geometric models showed strong concordance, with pairwise correlations of 0.90 or higher. In contrast, correlations between EBV from the hurdle Poisson model and the other models ranged from 0.36 to 0.39. The association of the sire infectivity EBV with the average observed NrSC per sire and the proportion of infectious index case daughters per sire was generally moderate with correlations between 44% and 47% and 65% to 69%, respectively. Agreement among models for identifying the genetically most infectious sires was also reasonable, with 151 out of 285 sires appearing in the top 10% across models, and 122 (42.8%) also aligning with the top 10% based on observed average NrSC. Results provide novel evidence for exploitable genetic variance in bTB infectivity allowing the derivation of meaningful EBV. Based on the estimated posterior mean genetic variances obtained, reduction in infectivity by 1 genetic SD would result in a 32% to 44% decrease in the expected NrSC per index case. Further research is warranted to refine the phenotypic definition of infectivity and assess correlation with other dairy traits. |
| format | Article |
| id | doaj-art-2ae20007ad2f471b8b2405dc9029bcc0 |
| institution | OA Journals |
| issn | 0022-0302 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | Elsevier |
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| series | Journal of Dairy Science |
| spelling | doaj-art-2ae20007ad2f471b8b2405dc9029bcc02025-08-20T02:27:34ZengElsevierJournal of Dairy Science0022-03022025-04-0110843835384910.3168/jds.2024-25697Detection of genetic variability in dairy cattle infectivity for bovine tuberculosisD. Madenci0E. Sánchez-Molano1M. Winters2A. Mitchell3M.P. Coffey4J.D. Hadfield5J.A. Woolliams6G. Banos7A. Doeschl-Wilson8The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian EH25 9RG, United KingdomThe Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian EH25 9RG, United KingdomAgriculture and Horticulture Development Board (Dairy), Stoneleigh Park, Kenilworth, Warwickshire CV8 2TL, United KingdomAnimal and Plant Health Agency, Surrey KT15 3NB, United KingdomScotland's Rural College, Easter Bush, Midlothian EH25 9RG, United KingdomInstitute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3FL, United KingdomThe Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian EH25 9RG, United KingdomScotland's Rural College, Easter Bush, Midlothian EH25 9RG, United KingdomThe Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian EH25 9RG, United Kingdom; Corresponding authorABSTRACT: This study investigated the genetics of bovine tuberculosis (bTB) infectivity in Holstein-Friesian dairy cows using British national data. The analyses included cows with recorded sires from herds affected by bTB outbreaks between 2000 and 2022. Animals were considered bTB positive if they reacted positively to the skin test, had positive postmortem findings, or both. We introduced the “index case approach,” based on the assumption that once the initial positively tested animals (index cases) are detected in a herd, subsequent infections (secondary cases) in the early stages of the breakdown are likely to be attributed to these animals. Genetic analysis of the number of secondary cases (NrSC) associated with a given index case was used to establish evidence of genetic variability in bTB infectivity of cattle, and derive EBV for infectivity for the sires of the index cases. Data were analyzed by employing Markov chain Monte Carlo techniques to fit generalized linear mixed models with either Poisson, zero-inflated Poisson (ZIP), hurdle Poisson, or geometric distributions. All 4 models demonstrated presence of genetic variance in cattle infectivity, with the strongest evidence provided by the ZIP and hurdle Poisson models. The hurdle Poisson model offered the most accurate and least biased predictions. Sire infectivity EBV from the Poisson, ZIP, and geometric models showed strong concordance, with pairwise correlations of 0.90 or higher. In contrast, correlations between EBV from the hurdle Poisson model and the other models ranged from 0.36 to 0.39. The association of the sire infectivity EBV with the average observed NrSC per sire and the proportion of infectious index case daughters per sire was generally moderate with correlations between 44% and 47% and 65% to 69%, respectively. Agreement among models for identifying the genetically most infectious sires was also reasonable, with 151 out of 285 sires appearing in the top 10% across models, and 122 (42.8%) also aligning with the top 10% based on observed average NrSC. Results provide novel evidence for exploitable genetic variance in bTB infectivity allowing the derivation of meaningful EBV. Based on the estimated posterior mean genetic variances obtained, reduction in infectivity by 1 genetic SD would result in a 32% to 44% decrease in the expected NrSC per index case. Further research is warranted to refine the phenotypic definition of infectivity and assess correlation with other dairy traits.http://www.sciencedirect.com/science/article/pii/S0022030224014413genetic analysisbovine tuberculosisinfectivitydairy cattle |
| spellingShingle | D. Madenci E. Sánchez-Molano M. Winters A. Mitchell M.P. Coffey J.D. Hadfield J.A. Woolliams G. Banos A. Doeschl-Wilson Detection of genetic variability in dairy cattle infectivity for bovine tuberculosis Journal of Dairy Science genetic analysis bovine tuberculosis infectivity dairy cattle |
| title | Detection of genetic variability in dairy cattle infectivity for bovine tuberculosis |
| title_full | Detection of genetic variability in dairy cattle infectivity for bovine tuberculosis |
| title_fullStr | Detection of genetic variability in dairy cattle infectivity for bovine tuberculosis |
| title_full_unstemmed | Detection of genetic variability in dairy cattle infectivity for bovine tuberculosis |
| title_short | Detection of genetic variability in dairy cattle infectivity for bovine tuberculosis |
| title_sort | detection of genetic variability in dairy cattle infectivity for bovine tuberculosis |
| topic | genetic analysis bovine tuberculosis infectivity dairy cattle |
| url | http://www.sciencedirect.com/science/article/pii/S0022030224014413 |
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