There is provided a milking system with a milking means, a milk line, and a sampling and analysis device (14) to sample and analyse the milk. The sampling and analysis device comprises a control unit, a tape wound on a tape reel (20), and comprising a base material (23) with a series of reagent pads (24) arranged to provide a detectable response in the presence of a substance in the sample, a tape mover to move and unwind the tape, a dosing device to provide a part of the sample onto one of the reagent pads, and an optical sensor device (28) to detect optical radiation from said reagent pad with said sample, and to analyse the detected optical radiation to provide an indication of a presence or concentration of said substance. The dosing device comprises a displaceable nozzle (25) with a supply line for supplying the sample to the nozzle. The nozzle is arranged for supplying the sample upwardly to the reagent pad. The dosing device further comprises a nozzle mover (38) to move the displaceable nozzle towards and away from the tape, and an overflow device, or cup (34), comprising a wall that surrounds the nozzle. An overflow space (35) is provided between the wall and the nozzle, and further comprises a discharge (36). The overflow device can collect excess fluid, both when sampling and certainly when flushing. Herein, gravity helps in collecting fluid, but importantly, also in supplying the sample, since the sample droplet cannot break off the nozzle unexpectedly.L'invention concerne un système de traite comprenant un moyen de traite, une canalisation à lait, et un dispositif d'échantillonnage et d'analyse (14) destiné à échantillonner et analyser le lait. Le dispositif d'échantillonnage et d'analyse comprend une unité de commande, une bande qui est enroulée sur un dérouleur de bande (20) et comporte un matériau de base (23) pourvu d'une série de tampons réactifs (24) disposés pour fournir une réponse détectable en présence d'une substance dans l'échantillon, un dis
