The Application Of Organic Selenium Source In Hen Production And Research For The Mechanism

Selenium(Se) is an essential trace element for animal and human health.Proper quantity selenium can regulate growth,enhance performance and immunity,prevent cancer, resist oxidation and stress,postpone aging,counteract some toxicant or detoxificate from some heavy metals,and prevent or control some local epidemic etc.Recent years,it was found that sodium selenite(SS) had disadvantages of oxidation characteristic,higher toxicity and lower bioavailability,and disbennifit for animal and environment.Organic selenium from organism had advantages of higher bioavailability, lower toxicity and less potential environmental pollution.It was advocated to explore and utilize organic selenium in feedstuff.Nowadays,selenium-enriched yeast(SY) is mainly source of organic selenium in stockbreeding,but its application was restricted for higher price.Selenium-enriched probiotics(SP) is a new organic selenium source product which resulted from translating inorganic selenium into organic selenium by probiotics fermentation according to biotransformation principle in our lab,acting as not only organic selenium but also probiotics.Study on its application in hen production was only preliminary.So,the present paper was conducted to compare the effects of SP with SS application in laying hen,at the same time,and to research for the relative mechanism from the levels of macroscopical,physiological and biochemical,cellular and molecular etc.Experiment 1.Effect of Selenium-enriched probiotics on the production performance, liver IDâ… activity and serum T₃ and T₄ of henEight hundred 58 week old healthy Rohman laying hens were allocated into eight groups according to feeding test requirement.Each group was replicated five times with five cages of four hens per cage in each replicate.Both selenium-enriched probiotics(SP) and sodium selenite(SS) were added into basal diet at 0.2,0.5 and 1.0 mg·kg^-1 of Se to make six experiment diets.Probiotics was added into basal diet to make probiotica control diet,and basal diet served as the blank control.Feeding test lasted for 35 days.The results showed thatâ‘ SP has a significant effect on the production performance of hen,whenas Se level has not.Se source and level both have a significant effect on liver IDâ… activity and serum T₃ and T₄ of hen.â‘¡Supplementation SP or probiotics can increase the laying rate of hen,hen day egg production and mean egg weight,and decrease feed/egg ratio,whenas the addition of SS can not.â‘¢The addition of either SP or SS can increase liver IDâ… activity and serum T₃,and decrease T₄ of hen.Especially when SP was supplemented,the liver IDâ… activity and serum T₃ of hen increased and serum T₄ of hen decreased as supplemental So level increased.Supplementation probiotics has not an effect on liver IDâ… activity,but can increase serum T₃ and decrease T₄ of hen.The results testified that there is a better effect of supplementation SP than those Of supplementation SS or probiotics.Experiment 2.Effect of Selenium-enriched probiotics on spleen selenium content and immune capacity of henExperiment design is same as the experiment 1.During the experiment,blood was sampled on days 14 and 28 for the T lymphocyte transformation of peripheral blood and the sertun IL-2 level assay.The results showed that supplemental Se from either SS or SP significantly increased Se content in spleen,significantly promoted the T lymphocyte transformation of hen peripheral blood,and increased the serum IL-2 level of hen.With supplemental Se level increase,selenium content in spleen,the T lymphocyte transformation of hen peripheral blood and the serum IL-2 level were also significantly increased.With the extension of experiment duration,the serum IL-2 level was also significantly increased,and supplemental SP had a more significant predominance in increasing the spleen Se content and the serum IL-2 level than SS or probiotics. Supplemental probiotics significantly increased the serum IL-2 level of hen only on days 28 of test.Experiment 3.Effect of selenium-enriched probiotics on selenium content and the antioxidant capacity of blood in henExperiment design is same as the experiment 1.During the experiment,blood was sampled on days 14 and 28 for whole-blood Se content and GSH-Px activity and plasma SOD activity and T-AOC value assay.The results showed that Both Se source and level signifioantly influenced on Se content and GSH-Px activity of whole-blood and plasma T-AOC.There was the higher Se content and GSH-Px activity of whole-blood and was the lower plasma T-AOC in hens fed by SS than those from hens fed by SP.The results testified that SP is a better source of Se for hens. Experiment 4.Effect of selenium-enriched probiotics on selenium content and the antioxidant eapacity of liver,kidney and heart in henExperiment design is same as the experiment 1.At the end of the experiment,2 hens per replicate from each treatment were slaughtered(n=10),and liver,kidney,and heart were sampled for Se content and GSH-Px,CAT,and SOD activity and T-AOC value assay.The results showed that supplemental Se significantly increase Se content and the activity of GSH-Px,CAT and SOD and T-AOC value in liver,kidney and heart of hens.With supplemental Se level increase,Se content and the activity of GSH-Px in liver,kidney and heart all were significantly increased.Supplemental SP had more ability than SS to increase Se content in liver and heart,and to increase the activity of GSH-Px and CAT in liver, kidney and heart and the activity of SOD and T-AOC value in kidney.It was advocated to supplement SP at a lower or medium Se level,0.2 mg·kg^-1 or 0.5 mg·kg^-1.Experiment 5.Effect of selenium-enriched probiotics on the mRNA levels of GPX-4 and IDâ… in hen liverExperiment design is same as the experiment 1.At the end of the experiment,2 hens per replicate from each treatment were slaughtered,and liver was sampled for the determination of mRNA levels of GPX-4 and IDâ… by method of Quantitative real-time PCR.The results showed that Se source didn't influence on mRNA level of GPX-4 in hen liver,and Se level significantly influenced on mRNA level of GPX-4.Both Se source and Se level significantly influenced on mRNA levels of GPX-4 and IDâ… in hen liver. Supplemental Se either from SP or SS significantly increased mRNA levels of GPX-4 and IDâ… in hen liver.With supplemental Se level increase,the mRNA level of GPX-4 increased (P＜0.05) and the mRNA level of IDâ… significantly increased(P＜0.01).Supplemental SP had more ability than SS to increase the mRNA level of IDâ… in hen liver(P=0.05).Experiment 6.Effect of selenium-enriched probiotics on selenium content,GSH-Px activity and Haugh units of eggTwo hundred and forty 60 week old healthy Rohman laying hens were allocated into eight groups according to feeding test requirement.Each group was replicated five times with six hens in each replicate.Both SP and SS were added into basal diet at 0.2,0.5 and 1.0 mg·kg^-1 of Se to make six experiment diets.Probioties was added into basal diet to make probioties control diet,and basal diet served as the blank control.Feeding test lasted for 35 days.On days 30 in the experiment,four eggs were randomly sampled from every replicate in each treatment for egg Se content,egg GSH-Px activity and Haugh units assay(n=20).The results showed that Both Se source and level significantly influenced on egg Se content.Selenium content of egg increased as supplemental Se level increased. Supplemental SP had a more ability to increase Se content in egg than SS.Se source didn't influence on GSH-Px activity and Haugh units of egg.Supplemental Se from either SS or SP significantly increased GSH-Px activity of egg,and reduced the fall of egg Hangh units in a different extent,and prolonged the time of maintaining fresh and shelf life in a certain extent.There was a significant positive correlation between Se content and GSH-Px activity in egg,and a significant negative correlation between egg GSH-Px activity and the fall of Haugh traits of egg stored at room temperature.Experiment 7.Effect of selenium-enriched yeast on tissue Se distribution and egg Se content in hensA 2×3 factorial arrangement in a randomized complete block(RCB) design was conducted to compare the effects of selenium-enriched yeast(SY) with sodium selenite(SS) on tissue Se distribution and blood and whole-egg Se concentrations in laying hens.Both Se sources were added into basal diet at 0.2,0.5,1.0 mg·kg^-1 of Se to make six experiment diets,and basal diet served as the control.Seven hundred health Rohman laying hens were allocated randomly into seven groups according to feeding test requirement and were investigated for 28 days.Each group was replicated 5 times with 5 cages of 4 hens per cage in each replicate.During the experiment,2 eggs per replicate from each treatment were colleeted every 7 days and blood was sampled on days 0,14 and 28 for whole-egg and whole-blood Se analyses.At the end of the experiment,2 hens per replicate from each treatment were slaughtered,and muscle(cardiac and breast muscles),liver,spleen and kidney were sampled for the determination of Se concentrations.The results showed that the addition of Se from either source caused a significant increase in whole-egg and whole-blood Se concentrations and Se concentrations in liver,kidney,spleen and cardiac and breast muscles of hen in comparison to the control.Both Se source and Se level significantly influenced Se concentrations in egg,blood and the above-mentioned tissues. There was a more significant increase in the Se concentrations in egg,spleen and breast muscle and significant decrease in whole-blood and kidney from hens fed SY than those from hens fed SS.The order of Se distribution was liver＞kidney＞spleen＞cardiac muscle＞egg＞blood＞breast muscle,irrespective of the addition level or source.Meat and eggs from hens fed SY are a potential source of Se for human. Experiment 8.Effect of selenium-enriched yeast on distribution and form of selenium in eggExperiment design is same as the experiment 7.During the experiment,2 eggs per replicate from each treatment were collected every 7 days for egg Se distribution and form analyses.The results showed that supplemental Se increased whole Se and organic Se content in whole-egg,yolk and egg white,and these indexs all were increased with dietary supplemental Se level increase.The effect of supplementation Se on egg Se distribution was consistent with the effect on egg Se form.Selenium from SY was deposited in egg more than Se from SS did,and mostly in egg white at an organic form of Se protein. Whenas Se from SS was deposited in yolk more than Se from SY did,mostly at an organic form of Se protein.