Farm‐level comparison of conventional and automatic milking farms differing in hygienic practices: Raw milk quality and suitability for ESL / UHT processing

Background/Context Extended shelf‐life (ESL) and ultra‐high temperature (UHT) milk production requires high raw milk quality to prevent storage defects such as sedimentation, phase separation and age gelation. Automatic milking systems (AMS) may alter milk quality compared with conventional milking systems (CMS), but their impact on ESL/UHT suitability remains underexplored. Aim(s) This study evaluated raw milk quality and ESL/UHT processing suitability in a farm‐level comparison between one CMS farm and one AMS farm with different hygienic management profiles. Methods Raw milk was collected fortnightly over 6 months from two Holstein farms (one CMS and one AMS). Compositional and microbiological parameters were measured, while hygienic practice and management characteristics were recorded descriptively. Selected milk was laboratory‐processed into ESL/UHT and stored for stability assessment (pH, sedimentation, phase separation, age gelation; n = 12 sampling days/farm). Major Findings Milk from the AMS farm had lower total bacterial count (3.42 vs 3.78 log10 cfu/mL), psychrotrophs (2.46 vs 2.81 log10 cfu/mL), coliforms and spore counts than milk from the CMS farm ( P < 0.05). ESL/UHT milk produced from the AMS‐farm raw milk also showed slower pH decline, reduced sedimentation and delayed phase separation/age gelation during storage. These differences were associated with farm‐level variations and coincided with the stronger hygiene and management practices recorded for the AMS farm, rather than the milking system alone. Scientific/Industrial Implications Automation should be viewed as a platform that can support consistent hygiene execution rather than as an independent microbiological control mechanism. For ESL/UHT production, dairy processors should prioritise raw milk sources with verified low psychrotrophic and spore loads, while farmers should focus on effective teat preparation, equipment cleaning, cooling and routine hygiene management regardless of milking system.