Prirodni zeolit klinoptilolit je mikroporozni alumosilikatni mineral čvrste anionske rešetke, otvorene trodimenzionalne strukture u čijim porama su izmjenjivi kationi. Dodatak zeolita u obroku sve se više primjenjuje u hranidbi životinja. Cilj pokusa bio je ustanoviti utjecaj dodatka mikroniziranog zeolita klinoptilolita na zdravlje vimena i sastav mlijeka krava različitih laktacija u uvjetima robotizirane mužnje. Krave su hranjene parcijalnim obrokom za krave u mužnji (PMR) s dodatkom 200 g po kravi mikroniziranog zeolita klinoptilolita (Zeotex®, Mevex, Hrvatska) i koncentratom na robotskoj jedinici za hranjenje, tijekom 42 dana pokusa. Značajno (P<0,05) manji broj somatskih stanica utvrđen je u mlijeku krava 1. i 2. laktacije nakon 42 dana konzumacije zeolita u odnosu na početak pokusa. Udio mliječne masti u mlijeku krava 1. laktacije bio je značajno (P<0,05) veći nakon 42 dana konzumacije zeolita u odnosu na početak i 21. dan pokusa. Značajno (P<0,05) veća koncentracija ureje u mlijeku utvrđena je nakon 21 dan konzumacije zeolita okusa u odnosu na početak pokusa kod krava nižih laktacija. Značajno (P>0,05) smanjenje broja somatskih stanica nakon 42 dana primjene zeolita u obroku mliječnih krava potvrđuje sposobnost zeolita da pozitivno utječe na zdravlje vimena. Smanjenje broja somatskih stanica samo kod krava u 1. i 2. laktaciji daje naslutiti ograničenu sposobnost zeolita prema kroničnim infekcijama vimena kod krava viših laktacija. Značajno (P<0,05), ali prolazno povećanje ureje u mlijeku 21. dana pokusa, vjerojatno je odraz prilagodbe mikropopulacije buraga na novonastale uvjete hranidbe dodatkom zeolita. Povećanje udjela mliječne masti kod krava u prvoj laktaciji govori u prilog pozitivnog djelovanja zeolita na poboljšanje kvalitete mlijeka. Natural zeolite clinoptilolite is a microporous aluminosilicate mineral of an open three-dimensional solid anionic lattice structure with pores of exchangeable cations. The addition of zeolite in the diet is increasingly being used in animal nutrition. The aim of the experiment was to establish the effect of micronized clinoptilolite zeolite on udder health and milk composition of cows of different lactations under conditions of robotic milking. Cows were fed a partial mixed ration (PMR) for milking cows with the addition of 200 g per cow of micronized clinoptilolite zeolite (Zeotex®, Mevex, Croatia) and concentrate on a robotic feeding unit for 42 days of the experiment. Significantly (P <0.05) lower number of somatic cells was found in the milk of 1st and 2nd lactation cows after 42 days of zeolite supplementation compared to the beginning of the experiment. The content of milk fat in the milk of lactating cows was significantly (P <0.05) higher on the 42nd day of the experiment compared to the beginning and the 21st day of the experiment. Significantly (P <0.05) higher urea concentration in milk was found on the 21st day of the experiment compared to the beginning of the experiment in lower lactating cows. A significant (P> 0.05) reduction in the number of somatic cells after 42 days of zeolite application in the diet of dairy cows confirms the ability of zeolite to positively affect udder health. The decrease in the number of somatic cells in cows of only 1st and 2nd lactation suggests a limited ability of zeolites to chronic udder infections in higher lactating cows. Significant (P <0.05), but transient increase in urea in milk on day 21 of the experiment, is probably a reflection of the adaptation of the rumen micropopulation to the new feeding conditions with the addition of zeolite. The increase in the content of milk fat in cows in the first lactation speaks in favor of the positive effect of zeolite and the improvement of milk quality.