Effect of graded concentration of organic zinc (zinc glycinate) on skin quality, hematological and serum biochemical constituents in broiler chicken

Abstract

Day-old chicks (120) were randomly distributed to 4 dietary groups with 6 replicate in each and raised for 42 days under uniform managemental conditions to determine the effect of supplementing organic zinc (zinc glycinate, Zn-gly) at lower levels on skin quality, haematological and serum biochemical constituents. Dietary treatments consisted of adding 30, 20 and 10 ppm Zn from Zinc glycinate and 40 ppm Zn (NRC 1994) from ZnSO4 (inorganic) (control) to a corn-soybean meal basal diet prepared as per NRC (1994) nutritional requirements, except Zn. Feed and water was provided ad-libitum. Haematological and serum biochemical constituents were estimated in blood collected at 35 d. At the end of experiment, representative samples of skin were collected from slaughtered birds for histological examination. Haematological constituents (WBC, RBC, Hb concentration, PCV, MCV and lymphocyte concentration), serum total protein, albumin and glucose concentrations did not vary with concentration (10–40 ppm) and source (ZnSO4 or Zn-gly) of Zn supplementation in diet. The cholesterol and albumin to globulin ratio was lowest (P<0.05), while globulin, Zn concentrations and alkaline phosphatase (ALP) activity in serum was highest (P<0.05) at 30 ppm Zn supplementation from Zn- gly compared to other groups and these attributes were comparable between 20 ppm Zn as Zn-gly and 40 ppm Zn as ZnSO4. An increased epithelial cell layer and collagen content was observed with 30 ppm Zn supplementation as Zn-gly compared to other dietary treatments. While epithelium cell layers and collagen content was moderate with addition of 40 ppm Zn as ZnSO4 or 20 ppm Zn as Zn-gly. The skin of birds supplemented with 10 ppm Zn from Zn-gly had few epithelial layers and low amount of collagen. Higher ALP activity indicating higher bioavailability, better skin quality and globulin concentration in serum was observed in birds fed 30 ppm Zn from Zn-gly compared to 40 ppm Zn supplemented from inorganic source. Reducing the dietary Zn supplementation by 50% (20 ppm) from organic Zn had comparable skin quality, serum ALP activity and globulin concentration as 100% (40ppm) supplementation from inorganic source.