The Effect of Dietary Zinc Source and Level on Carcass Defects in Broilers

 

 

Hematomas, skin ruptures, and epiphysiolysis (bone protrusion) are costly defects observed in European poultry abattoirs. Zinc deficiency has been shown to disrupt endothelial barrier, decrease skin strength and deteriorate skeletal integrity. The aim of this study was to determine the effect of Zn source in reducing these defects. A total of 1296 day-old Ross 308 male broilers were allocated to one of four dietary treatments: 40 ppm Zn supplemented as ZnSO4 [40ZS], 40 ppm Zn as zinc amino acid complex (Availa®Zn, Zinpro Corporation, Eden Prairie, USA) [40AZ], 80 ppm Zn as ZnSO4 [80ZS], or 40 ppm Zn as ZnSO4 + 40 ppm Zn as zinc amino acid complex [40/40].

 

The experimental design was a randomized complete-block, with each treatment having 12 replicate pens of 27 birds. Birds were processed at 35 d of age, when determination of carcass characteristics and scoring of pododermatitis, hock lesions, and carcass defects were conducted. Weights and yields of carcass and breast, incidence of pododermatitis, and hock lesions were not affected (P > 0.05) by dietary treatment. Bone protrusion was affected by Zn source, with less severe bone protrusion observed in carcasses of birds fed 40/40 compared to 40ZS, while 40AZ and 80ZS treatments were intermediate (1.8, 9.2, 3.3, 4.2 %, respectively; P < 0.05). Proportion of carcasses with mild bone protrusion was higher in treatments with zinc amino acid complex (40AZ, 20.6%; 40/40, 23.9%), compared to inorganic Zn source (40ZS, 10.1%; 80ZS, 10.0 %), P < 0.05. Proportion of carcasses without skin rupture was greater (P < 0.05) when 80 ppm supplemental Zn was provided, compared to 40 ppm Zn as ZnSO4 (40/40, 64.4 %; 80ZS, 55.8 %; 40ZS, 37.8 %), while sole source zinc amino acid complex (40ZS) was intermediate (45.6 %). Proportion of carcasses without hematomas was greater (P < 0.05) with increasing level of zinc sulphate (40ZS, 39.4 %; 80ZS, 50.0 %). Extent of carcasses lacking hematomas was even higher (P < 0.05) with the inclusion of zinc amino acid complex (40AZ, 67.5 %; 40/40, 64.8 %).

 

These data show that supplementation of zinc amino acid complex decreased broiler carcass defects.         

 

Keywords: Zinc, Organic-Zn, carcass quality, hematomas, bone protrusion