Effect of inorganic and organic manganese supplementation on the performance and tissue manganese content of broiler chicks

The effects of dietary levels of manganese (Mn) in inorganic (MnO) and organic (Mn fumarate) forms were evaluated on cockerel chicks. A basal corn-soybean diet with 23 mg/kg Mn was supplemented with levels of 0, 30, 60 and 240 ppm Mn from both Mn sources. Each treatment was replicated in five pens of 10 chicks. The chicks were fed diets ad libitum from 14 to 49 days of age, after which five birds per treatment were sacrificed for pathomorphological examinations and analysis. The treatments did not exert significant effects on the body weight (BW), the feed/gain (F/G) ratio or the mortality rate. According to the necropsy findings, no growth retardation or emaciation occurred in either of the groups and the differences in the average absolute and relative organ weights were not significant (P > 0.05). Tissue analysis indicated that the tibia showed the greatest response to Mn, followed by the liver and kidney. Accumulation in the tibia was higher (P < 0.05) with supplements of 30, 60 and 240 mg/kg from both Mn sources (3.71, 3.78, 4.44, and 3.68, 4.00, 4.36 mg/kg DM, MnO and Mn fumarate, respectively) compared to the control group (3.21 mg/kg). Accumulation in the liver increased significantly (P < 0.05) only with supplements of 60 and 240 ppm independently of the Mn source (12.7, 14.2, and 14.0, 14.9 mg/kg, respectively) compared to the control (9.8 mg/kg). Similarly, kidney tissue Mn was higher (P < 0.05) only with supplements of 60 and 240 ppm (12.8, 12.8, and 13.1, 12.5 mg/kg, respectively) compared to the control (10.2 mg/kg). At the same level of supplementation of the two Mn sources there were no significant differences (P > 0.05) between the Mn concentrations of organs and tissues. Droppings sensitively reflected the intake, whereas blood plasma and feathers showed only the extreme Mn loading.