Effects Of Chitosan Nano-selenium On Production Performance And Antioxidant Function Of Laying Hens During Late Laying Period

In modern large-scale intensive breeding,laying hens are living in a living environment with multiple stress factors.At the late stage of laying,the tissues and organs of laying hens show different degrees of aging,damage,reproductive and metabolic function decline,resulting in the accumulation of a large number of free radicals and harmful substances in laying hens,thus the laying rate,egg quality decline or even stop production.Therefore,we need to take appropriate control measures to increase its antioxidant capacity,ensure the health of the body and prolong the laying period.Chitosan nano-selenium(CS-Se NPs)has the characteristics of high safety,low price,good biocompatibility and low cytotoxicity.It is a new type of organic selenium source that can improve the antioxidant capacity,but it is less explored in the late laying period of laying hens.Therefore,the purpose of this experiment was to study the effects of adding chitosan nano-selenium to the basal diet on the production performance,antioxidant function and tissue health of laying hens in the late laying period,and to provide data support for production application.In this experiment,600 48-week-old healthy Roman laying hens were randomly divided into 5 groups with 6 replicates in each group and 20 hens in each replicate,120 hens in each group.They were blank group(BC),sodium selenite group(SS),chitosan nano-selenium low dose group(CS(L)-Se NPs),chitosan nano-selenium middle dose group(CS(M)-Se NPs),chitosan nano-selenium high dose group(CS(H)-Se NPs).The control group was fed a basal diet,the sodium selenite group was supplemented with0.3 mg / kg sodium selenite on the basis of the basal diet,the chitosan nano-selenium high-dose group,the chitosan nano-selenium middle-dose group and the chitosan nano-selenium low-dose group were supplemented with 0.1 mg Se/kg、0.3 mg Se/kg、0.5mg Se/kg chitosan nano-selenium(calculated by selenium content)on the basis of the basal diet,respectively,and the drugs were mixed evenly with the feed by equal addition.The pre-test period was 1 week,and the formal test period was 56 days for 8 weeks.Serum,liver,oviduct and ovary were collected at the 4th and 8th week of the experiment.Results showed:(1)Chitosan nano-selenium had the effect of prolonging the laying cycle of laying hens.The CS(L)-Se NPs group could increase the Haugh unit of eggs at the 4th and 8th weeks and the eggshell strength at the 6th week(P < 0.05).CS(M)-Se NPs group and CS(H)-Se NPs group could increase the Haugh unit of eggs at week 4(P < 0.05).(2)SS group increased the selenium content of eggs at the 4th week(P < 0.05),decreased the liver index and increased the selenium content of liver at the 8th week(P <0.05).The CS(L)-Se NPs group increased the selenium content of eggs in the fourth week compared with the BC group(P < 0.05),decreased the fallopian tube index in the eighth week(P < 0.05)and increased the selenium content of fallopian tubes(P < 0.05).The CS(M)-Se NPs group increased the selenium content of serum and egg at the 4 th week and the selenium content of serum,liver and ovary at the 8 th week(P < 0.05).The CS(H)-Se NPs group increased the selenium content of eggs at 4 weeks(P < 0.05),increased the fallopian tube index and the selenium content of serum and liver at 8 weeks(P < 0.05),and decreased the selenium content of eggs at 8 weeks(P < 0.05).In the BC group,there were more fat vacuoles in the liver and a small number of inflammatory cells in the late laying period.The oviduct cilia were atrophied and a small amount of secretion vacuoles were observed.The ovarian medulla was vacuolar degeneration,and the follicular cell granular layer was thin and loosely arranged.After using low and medium doses of chitosan nano-selenium,the liver,fallopian tubes and ovaries of laying hens in the late laying period were improved.The liver fat vacuoles in the CS(L)-Se NPs group and the CS(M)-Se NPs group were significantly reduced,the atrophy of fallopian tube cilia was improved,and the granular layer of follicular cells in the ovary was thickened and arranged closely.The CS(H)-Se NPs group had mild adverse reactions to the liver,and had a certain improvement effect on the fallopian tubes and ovaries,but the effect was not obvious.(3)CS(L)-Se NPs group increased T-SOD activity and MDA content in liver,GSH content,T-SOD activity and TXNRD1 expression in oviduct,GSH content,T-AOC activity and GPX1,TXNRD2 expression in ovary at 4 weeks(P < 0.05).The serum GSH content and T-AOC activity,liver T-SOD and T-AOC activity,oviduct T-SOD activity and SELENOP,SELENOU expression levels,ovarian GSH content,T-SOD activity and GPX1,SELENOP,expression levels were increased at 8 weeks(P < 0.05).The CS(M)-Se NPs group increased the GSH content and T-SOD activity in the liver,the GSH content and T-SOD activity in the ovary,and the expression levels of GPX4 and TXNRD2 at the 4th week(P < 0.05),and increased the T-SOD activity and the expression levels of SELENOU and TXNRD1 in the liver,the expression level of SELENOU in the oviduct,the GSH content and T-SOD activity in the ovary at the 8th week(P < 0.05).The CS(H)-Se NPs group increased the expression levels of GPX2 and TXNRD2 in the liver,the GSH content in the ovary and the expression levels of GPX4,SELENOP,TXNRD1 and TXNRD2 in the fourth week(P < 0.05),and increased the GSH content in the liver,T-SOD activity and TXNRD1 expression level in the eighth week,the GSH content in the fallopian tube and the GSH content in the ovary(P < 0.05).The MDA content of serum,fallopian tube and ovary at 4 weeks and serum and ovary at 8 weeks decreased significantly(P < 0.05),and the MDA content of liver increased(P < 0.05).In summary,CS-Se NPs can prolong the laying cycle of laying hens and improve egg quality.Appropriate addition of CS-Se NPs helps to improve the health of liver,fallopian tubes and ovaries.Excessive CS-Se NPs will have certain adverse effects.Appropriate addition of CS-Se NPs can improve the antioxidant capacity of serum,fallopian tubes and ovaries.Comprehensive analysis,adding 0.1 mg Se/kg CS-Se NPs is more conducive to the health and production of laying hens.