Two hundred multiparous Holstein dairy cows post-partum were randomly assigned into two groups. The first group (control, n=100) was fed total mixed ration (TMR) without a supplement of liquid probiotic enzymes. The second group (treatment, n=100) was fed TMR supplemented with a commercial probiotic (ZAD) prepared by Bactizad company, Cairo, Egypt. at the rate of 10 ml/head/day.  According to the guide of the manufacture for 12 weeks ZAD was added and mixed to the TMR at the time of feeding once per day. Each group was placed in a shaded pen equipped with free stalls. 
 
Results obtained showed that  
 
Milk yield increased significantly from 39.57 kg/day for control group up to 41.73 kg/day for treated with ZAD group.  Fat and protein milk percentage tended to be improved due to treated with ZAD but the difference was not significant. Lactose percentage was affected positively and significantly by treated of ZAD, lactose percentage was 4.79 for control group and 4.83 for ZAD group.  Serum total protein increased significantly from 11.52 (g/dl) for control group up to 11.85(g/dl) for treated ZAD group. Albumin was significantly higher in control group.   Results indicated that blood urea concentration in treated group being 34.77 (mg/dl) and for the control group 33.91 (mg/dl), was significantly higher.  Alkaline phosphates increased significantly in treated group from 21.105 U/l for control group up to 26.92 U/l for treated group.  
Cholesterol concentration was reduced significantly due to treatment from 240.98 mg/dl in control cows to 190.13 mg/dl in treated cows.  Triglycerides concentration declined significantly due to treatment of probiotic ZAD. In control cows triglycerides concentration was 27.871 (mg/dl) and treated cows was 20.9781 (mg/dl).  T3 concentration increased significantly as a response to treatment by probiotic ZAD. T3 concentration was 117.29 ng/dl in treated group and 62.38 mg/dl in control group.