Response of commercial broiler chicks to supplemental manganese in diets

An experiment was conducted with 180 commercial broiler chicks up to 6 weeks of age to study the effect of manganese (Mn) supplementation on performance, immune response, nutrient retention and carcass traits. The chicks were equally distributed into 6 groups with 6 replicates of 5 chicks each and offered ad lib basal diet supplemented with Mn at 0, 20, 40, 60, 80 or 100 ppm. Body weight gain, feed intake, feed conversion ratio, antibody titres against sheep red blood cells, ready to cook yield, giblet weight, tibia weight and tibia ash were not influenced by Mn supplementation to the basal diet. Abdominal fat increased (P<0.05) with Mn levels at or below 40 ppm, and the trend reversed with supplementation of Mn at 60 ppm or more. The balance trial showed higher retention (P<0.05) of Ca and P in birds fed 100 ppm Mn. The leg scores were higher (P<0.05) when Mn was offered at 40 ppm or less, which were corrected by raising Mn level to 60 ppm or more. Leg abnormalities were noticed in the 4^th week and, the severity increased with age. Mn content in tibia or in bone ash was not influenced by Mn supplementation at the highest level, but its uptake by liver increased linearly up to 60 ppm level. It was concluded that supplementation of Mn at 60 ppm to maize-soybean diet (37 ppm Mn) was essential for better leg health and mineral retention by liver tissue. Lower Mn levels were however, adequate to maintain optimum body weight, feed conversion ratio, carcass traits, bone mineralization and immune response.