Effects of different dl-selenomethionine and sodium selenite levels on growth performance, immune functions and serum thyroid hormones concentrations in broilers.

摘要: This trial was conducted in a 2 × 3 + 1 factorial arrangement based on completely randomized design to evaluate the effects of different dl-selenomethionine (dl-Se-Met) and sodium selenite (SS) levels growth performance, immune functions serum thyroid hormones concentrations broilers. A total 840 Ross 308 broilers (7 days old) were allocated by body weight seven treatments (three replicates 40 birds each treatment) including (1) basal diet (containing 0.04 mg selenium (Se)/kg; control) without supplementary Se; (2, 3 4) diet + 0.05, 0.15 or 0.25 mg/kg Se as SS; (5, 6 7) dl-Se-Met. The experiment lasted 42 days. results revealed that dietary supplementation improved (p < 0.05) average daily gain, feed efficiency, organ index, immunoglobulin (IgA), G (IgG), M (IgM) triiodothyronine (T3 ) decreased (p < 0.01) thyroxine (T4 )/T3 ratio compared with control. Broilers receiving dl-Se-Met-supplemented diets had higher thymus amounts IgA, IgG, IgM T3 well lower T4 /T3 than those consuming SS-supplemented diets. Serum IgA fed 0.15 mg Se/kg significantly 0.05 0.25 mg Se/kg. In summary, we concluded dl-Se-Met is more effective SS increasing immunity promoting conversion , thus providing an way improve performance Besides, consideration all indices, suggested be optimal level under conditions this study.