The oral  use of  Pediococcus (23×10⁶ CFU/calf/day) in drinking milk once a day for one month from January till February 2020 in Holstein's calves, induced  a highly significant effect on metabolic hormones, protein electrophoresis and bodyweight.  Moreover, it improved the future reproductive performance of the female calves. Albumin and Gamma globulin percentages showed a significant increase in Pediococcus treated group compared to the control one. Also, there was a significant increment in insemination body weight and milk production in the treated female group compared to the control groups. On the other hand, there was a significant decrease in levels of triiodothyronine (T3) and thyroxin (T4), and alpha globulin % in groups treated by Pediococcus. Besides, there was a significant decrease in insemination age and service conception in the treated female group compared to the control female groups. Moreover, there were non-significant changes in beta globulin % in the same groups compared to the control groups. Our results concluded that the use of Pediococcus (23×10⁶ CFU/calf/day) orally in drinking milk once daily for one monthhas highly significant effects on metabolic hormones, protein electrophoresis, body weight gain in calves;  moreover, it improves the future productive and reproductive performance of the female calves.