Evaluation Of Different Selenium Sources On Laying Hens

This thsis was conducted to compare the effect of different selenium sources on performance,egg quality,plasma antioxidant capacity and egg selenium concentration of laying hens. In addition, investigate the effects of different levels of selenium yeast and HMSeBA on laying hens.Experiment 1. Effect of dietary supplementation of different sources of selenium on laying performance and plasma antioxidant activity of laying hensThis experiment was conducted to compared the effects of selenium(Se) supplementation as forms of sodium selenite(SS), selenium yeast(SY),selenomethionine(SM), nano-selenium(NS) or HMSeBA on laying performance, egg quality, plasma antioxidant activity and egg Se content in laying hens, with the aim to provide theoretical guidance for the application of selenium sources for laying hen industry. six hundred and forty eight healthy Hy-Line grey laying hens of 18-week-old were randomly allotted into 6 groups with 6 replicates of 18 hens each. The control group was fed a basal diet without addition of exogenous Se source. The other five groups were fed the basal diet supplemented with SS, HMSeBA, SY, SM or NS containing 0.30 mg/kg Se, respectively(the analyzed values of selenium content in experimental diets were 0.08, 0.37, 0.37, 0.38, 0.34 and 0.41 mg/kg, respectively). The feed trail lasted for eight weeks followed an adaptation period of one week. The results showed as follows: 1) There were no significant differences on laying performance and egg quality among different treatments(P>0.05). 2) Compared with the control group, the addition of the 0.30 mg/kg of different five sources selenium in the feed could increase the SOD activity. At the end of the 4th week, SOD in the group of HSeMBA and SY was significantly high than that in the control group(P<0.05); at the end of the 8th week, there were no significant difference between different groups(P>0.05). Compared with control group, the addition of the different sources could decrease the MDA content. At the end of the 4th week, there were no significant difference between different groups(P>0.05). At the end of the 8th week, MDA content in the group of HMSeBA and SM were significantly high than that in the control(P<0.05).Compared with the control group, dietary addition of 0.30 mg/kg Se increased the glutathione peroxidase(GSH-Px) activity significantly(P<0.05)at the end of the 4th week. The GSH-Px activities in SY group and NS group were much higher, and GSH-Px activity in the SY group was slightly higher than that in the NS group; Compared with the control group, total antioxidant capacity(T-AOC) in other groups are higher, and T-AOC in NS group was most high than others at the end of 4th and 8th week.Compared with the control group, the addition one of the 5 sources of selenium in the basal diet could significantly increase egg Se content(P<0.05), and the egg Se content was elevated most in SY group and HMSeBA group.(Conclusion) Taken together, GSH-Px activity and T-AOC in plasma of laying hens could be markedly improved by addition of any of the five sources of selenium especially with SY or NS. Laying performance and egg quality were not affected by selenium sources. And the Se content in egg could be deposited more efficiently by SY and HMSeBA addition than other sources of selenium like SS, SM or NS.Experiment 2 Evaluation of the tolerance of selenium yeast on laying hensThe objective of this experiment was to evalutation the tolerance of selenium yeast on laying hens. Five hundred and seventy-six 21-week-old healthy Hy-Line Brown laying hens with a similar laying rate were randomly assigned to 6 groups with 6 replicates in each group and 16 laying hens per replicate. The control groups was fed a basal diet with background Se level of 0.08 ppm dry matter(DM), while the diets of experimental groups were fed the basal diet supplemented with selenium yeast containing 0.30, 0.60, 0.90, 3.0 and 15.0 ppm, respectively. Pre-trail period was one week and experimental period was 8 weeks. The results showed as follows: 1) Compare with the control group, the supplementation of 0.90 mg/kg Se(in the form of selenium yeast) could significantly increase laying rates(P<0.05),but laying rate, average daily feed intake,body weight at the end of the 8th week and rate of abdominal fat in the group of 15.0mg was significantly decreased(P<0.05),there were no significant difference among different groups for average egg weight and feed to egg ratio(P>0.05)2)Supplementation of different levels of SY has a significantly influence on eggshell thickness,yolk color and eggshell rate(P<0.05), eggshell thickness,yolk color and eggshell rate in the group of 15.0mg/kg was significantly decreased(P<0.05).There were no significant influence between different groups for egg index, eggshell strength, albumen height, haugh unit, albumen rate and yolk rate(P>0.05).3)There were no significant difference among different groups for RBC,WBC,HCT and HGB(P>0.05), at the end of the 8th week, WBC in the group of 0.30mg/kg was significantly high than all the groups except the group of 0.60mg/kg(P<0.05).4) For the biochemistry indices,there was a significantly difference among all the groups for ALT,AST and CRE-KU(P<0.05).ALT: ALT in the group of 15.0mg/kg was significantly high than that in the group of 0.30 mg/kg. AST: there were no significant difference among all the groups at the end of the 4th week(P>0.05), but at the end of the 8th week the AST in the group of 15.0mg/kg was significantly high than that in the group of 0.30mg/kg(P<0.05).CRE-KU:CRE-KU in the group of control and 15.0mg/kg was significantly high than that in the group of 0.30 mg/kg(P<0.05). There were no significant difference among all the group for the other biochemistry indices(P>0.05)5)The supplementation of different levels of selenium yeast could increase the egg selenium concentration effectively(P<0.05), the selenium concentration in the egg increased along the dietary selenium increased(R2=0.9790). In conclusion, the supplementation of different levels of selenium in the dietary could influence the laying performance and egg quality, increase the egg selenium concentration effectively. But 15.0 mg/kg caused average feed intake and body weight decreased, liver hepatic transaminase increased, do harm to the healthy. As a result, we suggest that the supplementation of the selenium in the feed of laying hens should less than 15.0 mg/kg.Experiment 3 Evaluation of the tolerance of HMSeBA--a new organic selenium feed additive in laying hensThis experiment was conducted to evaluate the tolerance of HMSeBA--a new organic selenium feed additive in laying hens according to Production performance, Egg quality, Hematological indices, Plasma biochemical indices, Plasma antioxidant parameters, Organs coefficients, Diet, egg and muscle Se concentration and Histopathological assessment. Four hundred and thirty two healthy Hy-Line grey laying hens of 18-week-old were randomly allotted into 4 groups with 6 replicates of 18 hens each. The control group was fed a basal diet without addition of Se. The other three groups were fed the basal diet supplemented with 0.30,0.50,5.0 mg/kg Se, respectively. The feed trail lasted for eight weeks followed an adaptation period of one week.The results showed as follows:1) Compared with control, the supplementation of high level(5.0 mg/kg) of selenium in the form of HMSe BA has no significant influence on production performance, egg quality, organs coefficients and Hematological indices. 2) The histopathological assessment results showed that there were no pathological changes happened on the tissue of heart, spleen, lung, kidney, thymus, pancreas, duodenum, ileum, rectum, lymph gland and marrow except liver. Mild fatty changes happened on partial liver cells. 3) There were no significant difference between different groups for antioxidant capacity and biochemistry indices 4) The use of HMSeBA in laying hen diets is very effective for increasing the Se content of eggs.The control has the least Se concentration and the group of 0.50 mg/kg has the most, respectively. As a result, we suggest that the tolerance level of the Se(in the form of HMSeBA) to the laying hens can be 5.0 mg/kg.