Thirty male and female Holstein calves were used to investigate the effects of natural clinoptilolite tuff (CP) on immunoglobulins and vitamin A absorption, fecal score and weight gain in newborn calves. Using a randamized complete design in the study, clinoptilolite was added to colostrum at levels 0.0, 0.5, 1, 1.5 and 2.0 grams per kg of body weight (BW) per day and fed to the newborn calves, 30 minutes after birth. Blood samples were collected at 0, 4, 8, 16 and 24 hours after the first colostrum feeding. The daily fecal score was evaluated in morning as well as in evening. The obtained results showed that the clinoptilolite effects on the serum immunoglobulins (IgG and IgM) were significant (P<0.01). Mean blood serum IgG and IgM at 24h, were the highest (22.41 g/l and 2.32 g/l) in the case of calves fed with 1.0 gram CP (kg/BW) and lowest (17.91 and 1.66 g/l) in control (not treated) calves. Mean concentration of vitamin A in blood serum was significantly (P<0.05) different among the treated groups, 63.66 ?g/dl in calves fed with 1.0g CP/(kg BW) while 51.00 ?g/dl in calves fed with 2.0g CP/(kg BW). The fecal score at first and second week was significantly different (P<0.05), 1.2 and 1.35 vs. 2.02 and 2.82 for calves treated with 1.0g and 2.0 g CP/(kg BW) respectively. The average daily gain (ADG) at the fourth, week of feeding was 0.35, 0.43, 0.41 and 0.41, 0.41 for 0.0, 0.5, 1.0, 1.5 and 1.0 g CP/(kg BW) respectively. In conclusion, the use of CP at 1.0g per kg BW/d exhibited the best effects on IgG, IgM and vitamin A absorption, average daily gain and reduction of fecal score.
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