Automatic milking and milk quality: effects of system and teat cleaning

With the introduction of automatic milking (AM) systems, some increases in total bacterial count (TBC) and of free fatty acids (FFA) in milk were observed. Contamination of milk, resulting in elevated TBC, originates from four main sources: inside of the udder, outside of the udder, the milking machine and bulk tank. The aim of this study was to investigate the efficacy of teat cleaning devices and to study the effect on milk quality of two and three system cleanings per day. AM systems have special teat cleaning devices. The efficacy of these teat cleaning devices was studied by contaminating the teats first, followed by swabbing the teats before and after teat cleaning. Per brand of AM system on two farms were taken. The effect of system cleaning frequency was studied on 13 farms by performing two or three system cleanings per day. Milk quality was determined on bulk tank samples. All teat cleaning systems showed positive effects. Differences were found between brands of AM systems. The level of housing hygiene influenced the level of teat contamination. Three system cleanings per day resulted in a significant lower TBC (10.000 vs. 13.000 cfu/ml), number of coliforms, thermodurics and psychrotrophs compared with two system cleanings per day. In both cases the levels found for TBC were far within the penalty limits.