RESPONSE OF BROILER CHICKENSTO ORAL ADMINISTRATION OF ZINC OXIDE NANOPARTICLES AND INORGANIC ZINCAT VARYING LEVELS

Abstract

ABSTRACT Antibiotics has been prohibited as growth promoters in poultry nutrition due to the emergence of a number of drug-resistant bacteria, drug residues in body tissue and organs, and presence of antibiotics residues in feed and environment. This has led to the promotion of alternatives that have positive characteristics without sacrificing efficiency and profitability. This study was conducted over a six week period to evaluate the response of broiler chickens to oral administration of varying levels of zinc oxide nanoparticles and inorganic zinc. A total of 216 old broiler chicks were assigned into six treatments, each divided into three replicates consisting twelve birds each. The experimental design was a 2x3 arrangement which comprises of two zinc types (nano zinc and inorganic zinc) included in fresh drinking water at 3 levels (0, 60 and 80 mg/l). Antibiotics were administered in drinking water of birds not given zinc (control group). Data were collected weekly on growth performance and on the 42nd day of the experiment, data were collected on blood profile, serum antioxidant activities, blood and meat lipid profile, carcass characteristics, zinc retention in blood, organs and muscles, bone morphometry, microbial load and immune response of the broiler chickens. Data were subjected to one-way analysis of variance. The result showed that the growth performance, serum antioxidant activities, lipid profile, carcass characteristics, caecal microbial load and immune response were not significantly (p>0.05) different between birds administered zinc oxide nanoparticles and inorganic zinc. However, significant (p<0.05) difference was observed in monocyte count of birds administered different zinc types, with birds administered inorganic zinc showing a higher percentage of monocytes. Different zinc levels significantly (p<0.05) influenced the retention of zinc in the heart, liver and blood of broiler chickens, with birds administered 80 mg/l of inorganic zinc showing the highest amount of zinc retained. Furthermore, tibia bone length was significantly (p<0.05) affected by varying levels of zinc administration, the birds administered 60 mg/l of zinc had an increased tibia length (101.26 mm) while birds administered antibiotics had the shortest bone length (94.09 mm). The bursa weight also increased significantly (p<0.05) with increasing levels of zinc administration. Additionally, zinc administration at various levels showed similar effect as the antibiotics administered to control group. Hence, this study recommends administering either of the zinc types at rate the of 60 mg/l for enhanced bone length and increased zinc retention in systems of broiler chicken as well as an alternative to antibiotics for caecal microbial load depopulation and improved immune response in broiler chickens.