Dataset Title Dataset: Duct-level evaluation of mammary gland health, somatic cell count and bacterial flora in lactating jennies ⸻ Authors Attili A.R., Gallina E.T., Storoni C., Massacci F.; Bazzano M., Duranti A.; Li Y.; Cuteri V. Corresponding author: Prof. Vincenzo Cuteri School of Biosciences and Veterinary Medicine University of Camerino, Italy vincenzo.cuteri@unicam.it ⸻ Dataset Description This dataset contains duct-level milk analysis results from a cross-sectional observational study conducted on 29 clinically healthy lactating jennies from six farms located in Central Italy (Umbria and Lazio regions). Each jenny was sampled at the individual duct level. Milk was collected separately from: • Right Lateral Duct (RLD) • Right Medial Duct (RMD) • Left Lateral Duct (LLD) • Left Medial Duct (LMD) A total of 116 duct-level samples were analysed. The study aimed to evaluate mammary gland health by integrating: • Somatic cell count (SCC) • Bacteriological culture with MALDI-TOF identification • Total bacterial count (TBC) • Selected host-related variables Study Design Non-randomised observational cross-sectional study. Milk sampling was performed under routine farm management conditions. No experimental treatments were administered. ⸻ Variables Included in the Dataset Animal-Level Variables • Animal_ID Anonymised identification code for each jenny. • Farm_ID Anonymised farm code. • AgeCat Age category (as defined in manuscript). • ParityCat Parity category. • LactStage Lactation stage: • 1 = 0–3 months • 2 = 4–6 months • 3 = 7–9 months • Aptitude Production aptitude (milk production or companion). ⸻ Duct-Level Variables • Duct Sampling site: • RLD = Right Lateral Duct • RMD = Right Medial Duct • LLD = Left Lateral Duct • LMD = Left Medial Duct • SCC Somatic cell count expressed as cells/mL. Determined using the direct microscopic method (Breed and Prescott). • SCC_cat_200k Exploratory categorical variable: • 0 = <200,000 cells/mL • 1 = ≥200,000 cells/mL (Note: no validated SCC cut-off exists for donkeys; this threshold was used for exploratory purposes only.) • TBC Total bacterial count expressed as colony-forming units per mL (CFU/mL). • Bact_Pos Bacteriological culture result: • 0 = No bacterial growth • 1 = Positive culture • Bacterial_Isolate Bacterial species identified by MALDI-TOF MS (when applicable). ⸻ Laboratory Methods Summary Somatic Cell Count (SCC) • Direct microscopic method (Breed and Prescott) • Newman–Lampert staining • Results expressed as cells/mL • Mean of two independent readings used Bacteriology • Culture according to National Mastitis Council guidelines • Selective and differential media • Incubation at 36 ±1 °C for 24–48 h • Identification by MALDI-TOF MS • Species-level identification accepted at log score ≥2.0 Total Bacterial Count (TBC) • Plating of 100 μL milk on Milk Plate Count Agar • Manual colony counting • Expressed as CFU/mL ⸻ Statistical Notes Due to non-normal distributions: • SCC and TBC were log10-transformed prior to regression modelling. • Mixed-effects linear regression models were used. • Animal ID was included as a random effect to account for clustering of four ducts within each jenny. Statistical analysis was performed using: • STATA v13 • GraphPad Prism v10 ⸻ Ethical Statement All procedures were conducted in accordance with national animal welfare regulations. Milk sampling was part of routine farm management practices and did not involve invasive procedures beyond standard milking. ⸻ Data Anonymisation All animal and farm identifiers have been anonymised. No personally identifiable information is included in this dataset. ⸻ Citation If you use this dataset, please cite: Attili A.R., Gallina E.T., Storoni C., Massacci F.; Bazzano M., Duranti A.; Li Y.; Cuteri V. Duct-level evaluation of mammary gland health, somatic cell count and bacterial flora in lactating jennies. Equine Veterinary Journal. (Under review)