Effects Of Selenium On Growth And Biochemical Indexes Of Caged Egg-type Ducklings

The experiment was conducted to study the effects of different levels of selenium(sodiumselenite) on growth performance and biochemical indexes in caged egg-type ducklings(0-4weeks).Using a single factor completely randomized design, a total of180one-day-old egg-typeducklings were randomly assigned to5groups,6replicates per group, and each replicatecontained6ducks. Group Ⅰi scontrol group, fed corn-soybean meal basal diet(0.042mg Se/kgdiet), groupsⅡ-Ⅴwere fed basal diet supplemented with0.1,0.15,0.2and0.3milligramselenium(actual additive:Na2SeO3) per kilogram diet (mg/kg), respectively. The experimentalperiod lasted for4weeks. In the experiment, the ducks weight and surplus feed were weightedevery week to calculate daily gain, daily intake feed and feed gain ratio. At the end of the feedingtrial,1duck with moderate weight selected in each replicates to collect fasting blood and slaughter,and then to take out the liver and immune organs including liver, spleen, bursa and thymus.The results of growth performance showed that the effect of different levels of Se hadsignificant effect influence on feed intake, daily gain and feed conversion ratio (P<0.01),supplementation of0.15mg/kg Se in diet significantly improved average daily gain, and reducedthe ratio of feed to gain.The results of antioxidant indicators showed that Se levels in diet had very significantlyincreased the activities of GSH-Px, T-SOD and T-AOC in serum(P<0.01), and the activities ofMDA concentration were very significantly reduced in serum. The group of adding0.15mg/kg Sewas the best. The activities of GSH-Px、T-SOD、T-AOC and MDA concentration with supplementof0.15mg/kg Se was much higher than those in the control group in liver(P<0.01).With Se levelsincreasing, the activity of GSH-Px, T-AOC, T-SOD was firstly increased and subsequentlydecreased, but MDA had the opposite tendency.The results of immune test showed that the level of Se levels in diet had no influence ofbursal index (P>0.05), but the bursal indexes increased with increasing of dietary Se level. Selevels in diet had a significant difference of spleen index(P<0.05), a very significant differenceinfluence of thymus index(P<0.01). Compared to the control group, add0.15mg/kg Se had a very significant increased of serum total protein (TP), albumin (ALB) and immunoglobulins (IgA, IgG,IgM) levels (P<0.01).The results of hormone in serum test showed that triiodothyronine(T3) and GrowthHormone(GH) first increased and then decreased as the level of Se increased, thyroxine(T4) andCortisol(Cort) had the opposite tendency. Compared to the control group, all test groups had verysignificant difference except0.30mg/kg Se of T4(P<0.01),0.30mg/kg Se of T4had significantdifference with control group (P<0.05).The results of serum physiological and biochemical indicators showed that as the level of Seincreased, concentration of alkaline phosphatase(ALP), lactate dehydrogenase(LDH) and bloodurea nitrogen(BUN) had different degrees of reduction. Compared to the control group, all testgroups had very significant difference except0.30mg/kg Se of LDH(P<0.01),0.30mg/kg Se ofLDH had significant difference with control group (P<0.05).According to growth performance, antioxidant capacity, immune function, biochemicalindicators and regression equation, addition of0.190mg/kg in the corn-soybean meal diets(he Secontent was0.042mg/kg) which can satisfy the growth requirements，and enhance antioxidant，immunity and other biochemical indexes.