Effects Of Different-source Zinc And Zinc Levels On Broiler's Performance, Intestinal Mucosal Morphology And Immuno-potency

To investigate the effects of different-source zinc and their levels on performance, mucosa morphology and immuno-potency on broilers, present study was conducted using 384 one-day old AA broilers with a 2×4 factorial design. Broilers were grouped randomly to 8 dietary treaments with 4 duplicates, each with 12 broilers. Zinc methionine and zinc sulfate were respectively supplemented at 30, 60, 90 and 120 mg/kg levels to make 8 different diets. Results indicated that:1. Effects on performance. Different-source zinc supplementation significantly enhanced ADG (P<0.05), with zinc sulfate even higher than zinc methionine; but not on ADFI (except the 3- and 6-week old ). On F/G. of 4～6 week old, it showed significant effects, but not on 1～3 week olds. Different zinc levels showed significant effects on ADG, ADFI and F/G of the 5～6 week old, but no effects on the 1～3 week old. 60mg/kg of zinc sulfate showed the best results. Zinc sources and levels had no significant effects on dressing percentage, eviscerated yield, eriscerated yield, breast meat percentage, leg muscle rate and abdominal at percentage (P>0.05).2. Effects on intestinal mucosal morphology. Zinc methionine supplementation could increase the length of villous and degrade the depth of crypt in duodenum, jejunum and ileum during week 0～3, but zinc sulfate was better during week 4～6.3. Effects on immunity. Different zinc sources and levels had no significant effects on Thymus, Bursa and Spleen index; neither on ANAE at 42 day old (P>0.05). Different zinc sources had no significant effects on th ymus (except 21day old), bursa and spleen index (P>0.05). Different zinc source and zinc levels had no significant effects on titers of serum antibody against Newcastle disease virus in early stage, but significant in late stage.4. Effects on blood physiology biochemistry index. Different zinc sources and zinc levels had no significant effects on the Serum Total Protein, Serum Albumin, MDA, AKP and T-SOD (P>0.05). Different zinc sources had significant effects on GSH-Px at 21day old (P<0.05), but not at 42 day old (P>0.05).Conclusion: Different zinc sources and zinc levels had no significant effects on immunity but zinc methionine was better than zinc sulfate. However supplementation of zinc sulfate at 60 mg/kg in 1～6 weeks to corn soybean diet showed best growth performance.