Effect of replacing inorganic zinc with a lower level of organic zinc (zinc propionate) on performance, biochemical constituents, antioxidant, immune and mineral status in buffalo calves

An experiment of 120 days was carried out to investigate the effects of replacing inorganic zinc (ZnSO₄; 80 ppm) with lower level (75% of inorganic levels; 60 ppm) of organic zinc (Zn propionate; Zn-Prop) on growth, serum biochemical constituents, immune response, mineral and antioxidant status in buffalo calves. Twelve buffalo calves (193.3±19.63kg; 14–24 months) were randomly allotted to a control (80 ppm Zn) and experimental (60 ppm Zn) diets. All calves were weighed at fortnight interval. Animals were immunized against Brucella abortus (BA) and chicken RBC (CRBC) antigens on day 90 with a booster dose of 15 days interval and serum was collected on 7, 14, 21 and 28 d of post sensitization (PS) to study the antibody titres. Blood was collected on 114 d of experiment to prepare serum and haemolysate. Cell mediated immune response (CMIR) was determined against phytohemagglutinin-P (PHA-P) on day 118. The fortnightly body weights, average daily gain, dry matter intake, feed conversion ratio were comparable between the dietary groups. Similarly, serum albumin, globulin, creatinine and mineral (Zn, Cu, Mn, Fe) levels were comparable while higher (P<0.05) serum total protein and alkaline phosphatase activities were observed in organic Zn supplemented calves. After 7 d of PS, serum antibody titres (log₂) against BA were higher (P<0.05) with Zn-Prop supplementation, while the titres against CRBC were not affected by Zn source and dose. Lipid peroxidation and antioxidant enzyme activities (glutathione reductase, RBC catalase and superoxide dismutase) estimated in haemolysate were comparable between groups, while glutathione peroxidase (P<0.05) activity increased with Zn-prop supplementation compared to ZnSO₄. The CMIR was higher (P<0.05) with organic Zn. It can be concluded that the growth performance, antioxidant status, and immune response in calves fed lower levels of organic Zn (Zn-Propionate) (75% of inorganic mineral supplementation) was comparable to those fed 100% of inorganic zinc and the CMI response was higher in organic Zn supplemented calves.