Robotic milking and milk quality. Effects on bacterial counts - somatic cell counts - freezing point and free fatty acids

Changes in milk quality after the introduction of automatic milking systems (AM-systems) on dairy farms in The Netherlands, Germany and Denmark were examined and the data were compared with milk quality results of farms with conventional milking technology. After introduction, a small, but significant increase in total bacterial count, somatic cell count, freezing point and free fatty acids was observed. The highest levels for total plate count and cell count are found in the first six months after introduction. After this period the milk quality slightly improves to a more stable level. Risk factors related with milk quality concern general farm characteristics, animal health, AM-system, cleaning and cooling, housing, management skills of the farmer and the hygiene on the farm. Total plate count was significantly related to milk yield of the herd, cleaning of the area around the AM-system and the overall hygiene on the farm. Bulk milk somatic cell count appeared to be significantly related to milk yield of the herd and the number of milkings before replacement of the liners. An increased milking frequency is not the only explanation of increased free fatty acid levels. Technical factors related to free fatty acids mainly concerned the air inlet in the teat cups, bubbling (excessive air inlet) and a too long post run time of the milk pump. However, several questions regarding the causes of increased free fatty acid levels remained unclear.