Efficacy of Different Zinc Sources in Broiler Production

Zinc (Zn), as an essential trace element, is a common feed additive for food producing animals. Zn is supplemented in either an inorganic or organic form. Literature suggests inconsistency among both sources regarding trace mineral availability and influence on animal performance, but organic trace minerals are considered to be advantageous (Schlegel et al., 2013). Between organic trace minerals, the chemical bond is the main difference. While mono-glycinates are complexes with one amino acid (AA) bound to a metal ion, bis-glycinates are chelates with two AAs bound to a metal ion. Two studies were conducted to determine the efficacy of different Zn sources in broilers. In Study I, 640 day-old male broiler chickens (Ross 308) were randomly allocated to one of five treatments (8 replicates; 16 animals/replicate; kept in cages): I-NC: no added Zn, I-ZnSO4: 80 mg/kg Zn from ZnSO4, I-MG: 40 mg/kg Zn from Zn mono-glycinate, I-BG: 40 mg/kg Zn from Zn bis-glycinate, I-Combo: 40 mg/kg Zn from ZnSO₄ + 20 mg/kg Zn from Zn bis-glycinate. Diets were based on corn, barley and soybean meal. At day 35, body weight and weight gain were numerically, but not statistically, lower in birds of the I-NC group than in Zn supplemented birds (P > 0.05). The highest body weight was observed in I-Combo, followed by I-BG, I-MG, I-ZnSO₄ and I-NC (2322, 2297, 2294, 2280, 2262 g, respectively). FCR did not differ (P > 0.05) between the treatments I-NC, I-ZnSO₄, I-MG, I-BG and I-Combo (1.49, 1.47, 1.45, 1.44, 1.45, respectively). In Study II, 210 day-old male broiler chickens (Ross 308) were randomly allocated to one of five treatments (21 replicates; 2 animals/replicate; kept in cages): II-NC: no added Zn, II-ZnO: 100 mg/kg Zn from ZnO, II-MG: 50 mg/kg Zn from Zn mono-glycinate, II-BG: 50 mg/kg Zn from Zn bis-glycinate, II-Combo: 50 mg/kg Zn from ZnO + 25 mg/kg Zn from Zn bis-glycinate. Diets were based on wheat, soybean meal and corn. At day 35, body weight and body weight gain were numerically, but not statistically, lower in birds receiving II-NC than in birds fed Zn supplementations (P > 0.05). The highest body weight was observed in II-BG, followed by II-Combo, II-MG, II-ZnO and II-NC (2262, 2237, 2230, 2159, 2141 g, respectively). FCR did not differ (P > 0.05) between the treatments II-NC, II-ZnO, II-MG, II-BG and II-Combo (1.34, 1.32, 1.32, 1.33, 1.34, respectively). Both trials showed a numerically better performance of birds fed with an organic trace mineral source. Compared to inorganic trace minerals, bis-glycinates may assist in supporting performance in poultry, while allowing a lower inclusion rate and may therefore contribute to a sustainable poultry production. A similar effect has been shown in piglets, where half the dosage of Cu from bis-glycinate led to the same performance as in animals fed the full dosage from CuSO₄ (Davin et al., 2019). Therefore, the environmental impact is less.