Effect of graded concentration of organic Zinc (Zinc glycinate) on antioxidants status and immune response in commercial broilers

One hundred and twenty day old commercial broiler chicks were randomly allotted to 4 dietary groups, with 6 replicates of 5 birds in each and reared for 42 days under uniform management conditions to study the effect of organic zinc (zinc glycinate; Zn-gly) supplemented at lower levels (30, 20 and 10 ppm) on antioxidant status and immune response in comparison to NRC (1994) recommended levels (40 ppm) of Zn supplemented from inorganic source (ZnSO4). The dietary treatments were corn soybean meal basal diet supplemented with 40 ppm Zn from ZnSO4 (inorganic) (control) and 30, 20 and 10 ppm Zn from Zn-gly (organic). Antioxidant enzyme levels and antibody titres against New castle disease (ND) vaccine (humoral immunity) were estimated on 35th d and oxidative stress markers from liver on 42nd d. On 40th d, the cell mediated immunity (CMI) was assessed as cutaneous basophilic hypertrophy to phytohemagglutinin-P (PHA-P). The lipid peroxidation in haemolysate (P<0.05) lowered in birds with 30 ppm Zn supplemented as Zn-gly compared to 20 and 10 ppm Zn from Zn-gly and 40 ppm Zn from ZnSO4. The Glutathione peroxidase enzyme activity was higher (P<0.05) with 30 ppm Zn as Zn-gly compared to control. The CMI was sgnificantly (P<0.05) high at 30 ppm Zn supplemented as Zn-gly compared to 40 ppm Zn as ZnSO4 and other organic Zn groups. The SOD activity, humoral and cell mediated immune resonse when fed 20 ppm Zn as Zn-gly was comparable to those on 40 ppm Zn as ZnSO4. The results of the study indicated that reducing the level of Zn from inorganic source (40 ppm) to 50 % (20 ppm) supplementation from Zn-gly can result in comparable immune and antioxidant status in broiler chicks.