Abstract
We evaluated the milk biomarkers cathelicidin (Cath), haptoglobin (Hp), milk serum amyloid A (M-SAA), N-acetyl-β-D-glucosaminidase (NAGase), lysozyme (LZ), and the half-udder milk somatic cell count (H-SCC), for their potential association with intramammary infections (IMI) in dairy goats across lactation stages. Half-udder milk from 105 goats was collected during early (39 ± 13 days in milk, DIM), mid (136 ± 12 DIM), and late (269 ± 12 DIM) lactation stages and analyzed for bacteriological culture (BC), H-SCC, and potential biomarker reactivity. Predictive performance was evaluated with BC as the outcome, and Dairy Herd Improvement records provided contextual production data. Cath positivity, assessed by western blot, showed the strongest association with positive BC in early lactation and performed well also in mid-lactation. A dynamic H-SCC threshold was reliably correlated with positive BC in early and mid-lactation. Hp positivity, assessed by Western blot, was associated with BC in mid-lactation, while NAGase, assessed by enzymatic assay, showed no consistent association. M-SAA, assessed by ELISA, suffered technical limitations due to a lack of dilution linearity, and LZ, assessed by enzymatic assay, showed no association with BC. Our data suggest stage-dependent associations and support further validation of Cath, Hp, and SCC as potential components of combined diagnostic panels, particularly in early and mid-lactation. However, a semi-quantitative Western blot assessment for Cath and Hp, as well as technical limitations for M-SAA, warrant cautious interpretation and further analytical validation.
Data availability
The data used for this study can be provided by the corresponding author (MFA) upon request.
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Acknowledgements
We thank Prof. Cristina Lecchi and Prof. Fabrizio Ceciliani for providing the anti-bovine Hp antibodies.
Funding
The research was supported by personal funds of M.F.A. and R.P. The authors acknowledge the support of the APC central fund of the University of Milan.
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Conceptualization: M.F.A.; Methodology: M.F.A., A.M., V.B., P.M., R.P.; Data curation: M.F.A, F.S., M.M.; Formal analysis: F.S., S.F.P., M.M., M.P., L.F.P.; M.M.V.; Visualization: M.F.A., M.M.; Resources: M.F.A, R.P; Writing—original draft preparation: M.F.A, F.S.; Writing—review and editing: all authors; Supervision: M.F.A.; Project administration: M.F.A, R.P.; All authors contributed to the manuscript and approved the submitted version of the manuscript for publication.
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The milk used for this study was collected during regular milking procedures from dairy goats. No specific activities were carried out on the animals for the purposes of the study but collecting milk from each half-udder in separate tubes at the scheduled milking time. Animals were farmed and kept in respect of all the guidelines and regulations under the supervision of the farmers and the farm veterinarian. Milking procedures were conducted by trained personnel in accordance with best practices for animal welfare and veterinary care. No experimental interventions or invasive procedures were performed on the animals for the purpose of this research. Therefore, ethical committee authorization was not requested. All methods were performed in accordance with the relevant guidelines and regulations and followed the Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines. The farmers provided their informed consent to collect the samples for the purposes of this study.
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Addis, M.F., Santandrea, F., Fusar Poli, S. et al. Comprehensive evaluation of milk biomarkers as indicators of intramammary infection in dairy goats across lactation. Sci Rep (2026). https://doi.org/10.1038/s41598-026-45097-w
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DOI: https://doi.org/10.1038/s41598-026-45097-w
