Effects of Hydroxychloride Zinc and Elevated Levels of Hydroxychloride Copper in Broiler Chickens’ Diet on Productive Traits and Gut Health

Trace minerals are often supplied in the forms of inorganic salts such as sulphates into poultry feed to meet the requirements. The ionic bonds in inorganic salts of minerals are very weak allowing the metal ion to disassociate once in contact with water, binding up diet antagonists such as other minerals, vitamins, and enzymes. To mitigate these negative effects technologies such as organic minerals or mineral complexes, which are less reactive, are used. In hydroxychloride minerals (Hyd) the metal ions are held together by a series of covalent bonds located between the metal ion, multiple hydroxyl groups and the chloride ions. This creates mineral complexes, which are more stable and can avoid unwanted interactions. Commercially, copper could be supplemented in broilers diet at far above nutritional levels (125 to 250 ppm), to improve gut health and growth performance as an alternative to antibiotic growth promoters. The current study aimed to investigate the effect of Hyd zinc (HyZn) and copper (HyCu) at different inclusion levels on productive traits and gut health biomarkers in broiler chickens. The five experimental diets were as follows: inorganic diet with 15 and 100 ppm Cu and Zn added in form of CuSO4 and ZnSO4 (INO), Hyd diet with 15 and 100 ppm Cu and Zn added in form of HyCu and HyZn (Hyd1), and Hyd diets with 80 ppm Zn as HyZn and either 100 (Hyd2) or 150 (Hyd3) ppm Cu as HyCu, and Hyd4 diet with 80 ppm Zn as HyZn with 200, 100 and 60 ppm Cu as HyCu in starter (1-10 d), grower (10-24 d) and finisher (24-35 d) diets, respectively. Each diet was replicated 11 times (18 male Ross 308 chicks per replicate). As summarized in Table 1, birds in all Hyd groups, regardless of HyCu levels, had a higher BW by 4 % on day 35 than INO group (P < 0.05). Hyd1 treatment improved FCR by 2.5 % compared to INO (1.455 vs 1.419; P < 0.01), adding 100 and 150 ppm HyCu, improved FCR by 3.8 and 3.2 %, respectively, compared to INO (P < 0.01). Feeding Hyd4 diet resulted in similar BW and FCR to Hyd2 diet (P > 0.05). Birds fed the INO diet had the lowest tibia breaking strength, breast meat yield and highest abdominal fat than all Hyd diets (P < 0.05). Bifidiobacteria counts determined through qPCR in ceca digesta tended (P = 0.06) to be higher in all Hyd groups than INO. Inclusion of higher HyCu in the diet significantly (P < 0.01) reduced cecal Entrobacteria count compared to Hyd1 and INO treatments. In conclusion, the results obtained in this study suggest that replacing ZnSO4 and CuSO4 with HyZn and HyCu in broiler chickens diet improves BW by around 80 g/bird and FCR by approx. 2.5 %. A higher dosage of HyCu up to 100 ppm results in a further 1.3 % improvement of FCR.

ACKNOWLEDGEMENTS: This study was financially supported by Trouw Nutrition, A Nutreco Company.