Effect of protein, probiotic, and symbiotic supplementation on serum biological health markers of molted layers.

Dietary zinc was used to induce molt in 200 White Leghorn birds in caged housing at the age of 70 wk. The birds were equally and randomly allocated to 4 groups each of 50 birds as G1 (control; CP 16%, no supplement), G2 (CP 18%, no other supplement), G3 (CP 16%, symbiotic Perfectin: 85 mg•L(-1) in drinking water daily), and G4 (CP 16%, probiotic Protexin: 85 mg•L(-1) in drinking water daily) after the completion of molt. The sampling was conducted 3 times at 5% production, peak production, and end of production with 15 birds being killed at each sampling from each group to collect the blood for harvesting of serum. Serum health markers including total oxidant status, total antioxidant capacity, homocysteine concentration, and paraoxonase, arylesterase, and ceruloplasmin activity were determined by the prescribed assays. The overall total antioxidant capacity was increased, whereas total oxidant status and homocysteine concentrations were reduced significantly (P ≤ 0.01) in all the supplemented groups compared with the control. The paraoxonase and ceruloplasmin activity were enhanced (P ≤ 0.01) in the supplemented groups compared with the control, and arylesterase activity was increased (P ≤ 0.01) in only G2 compared with the other groups. Although protein supplementation significantly reduced the oxidative stress, supplementation with symbiotic and probiotic also improved the health status by decreasing the oxidative stress in the birds.