An experiment was conducted to determine the effect of various levels )1 natural zeolite (clinoptilolite) on milk yield, milk compostion, and pH of rumen liquor and feces of Holstein cows. Twelve lactating animals (61:!:] 1 DIM) in a balanced chanageovcr design with four rations, three periods (2X-day), four blocks (three cnwshlnck) were used. Four total mixed rations containig 0, 2, 4 amI 6 percent of zeolite (ration 1, 2, 3 and 4) were prepared and fed to the cows individually for 91 days. The average milk yield and fat corrected milk (4%) of the cows which received rations L 2, 3 and 4 were
23.74, 24.36, 25.05 and 25.37 (not significantly different) ; and 21.1X, 22.34,
23.49 and 24.23 kg, significantly different (P
percentages [in the milk of the cows, fed the different rations I, but it was significant for the six percentage zeolite which increased the pH of the cow rumen and feces. As far as, economic of the rations is concerned, the rations
that contained 4 and 6% zeolite were: more profitable.
)