2006 Volume 43 Issue 4 Pages 371-377
Two feeding trials were simultaneously conducted using 240 and 120 broiler chicks (Hubbard) for evaluating the mineral retention by tissues and immune competence, respectively as influenced by manganese (Mn) levels in feed. Mn was added at 0, 100, 400, 800, 1600 or 3200ppm levels to a corn-soya basal diet, using sulphate salt. In both trials, chicks were uniformly distributed into 6 experimental groups and housed in stainless steel battery brooders. From 8-28 days of age, each experimental diet was fed ad libitum to one test group. Results indicated that Mn supplementation from 0-800ppm did not influence body weight gain or feed consumption, but a significant depression in both parameters was noticed at 1600 and 3200ppm levels. The feed conversion efficiency was however, not affected by dietary Mn levels. Excess (1600ppm and above) or non - supplementation of Mn increased leg abnormality scores. Mn levels above 400ppm significantly decreased Ca, P and Zn retention in tibia, which was related to higher leg scores. A linear increase of Mn content in bone, kidney, liver and pancreas was noticed with the increase of Mn in feed. The antibody titers against inoculation of sheep red blood cells or cutaneous basophil hypersensitivity to phytohaemagglutinin-P were not influenced by the dietary increases of Mn up to 800 or 1600ppm levels, respectively. Both responses were negatively affected by increased Mn levels in feed. Heterophil to lymphocyte ratios, the indicators of stress were not altered by Mn supplementation up to 800ppm, but higher levels produced wider ratios. In conclusion, supplementation of Mn at 100ppm level was essential for leg health, better retention of Ca, P and Zn in bone besides optimum immune response. Mn supplementation at 100ppm level was as efficient as higher levels (upto 800ppm). Higher levels of Mn (1600ppm and above) had negative effect on all parameters studied in broilers up to 28 days of age.
