Effects Of Vitamin A And Vitamin K₃ On Ovarian Reproductive Gene,Antioxidant And Immune Function Of Aged Laying Hens

The aging of laying hens cannot be avoided in the breeding process.In order to increase the profit of breeding,it is a common phenomenon to delay the elimination of laying hens.Therefore,delaying ovarian senescence and preventing ovarian dysfunction in laying hens have become problems that must be solved in the production of laying hens.The purpose of this experiment is to study the effects of Vitamin A（VA）and Vitamin K₃（VK₃）on ovarian function indexes,ovarian and jejunum antioxidant indexes,and immune indexes in aged laying hens.A 3×3 two-factor complete cross-sectional design（VA×VK₃）was used in this study.The supplemental levels of VA were set at 0,7000 and 14000 IU/kg,and the supplemental levels of VK₃ were set at 0,2.0and 4.0 mg/kg,respectively.In this experiment,there are 1080 laying hens that are 88-week-old were randomly divided into 9 treatment groups with 8 replicates per group and 15 hens per replicate.The control group was fed basal diet,and the treatment group was fed diets supplemented with different levels of VA and VK₃.In this experiment,the prefeeding period was 2 weeks,and the formal experiment was started from the age of90 weeks of laying hens,which lasted for 8 weeks.The test results show that:1.Effects of VA and VK₃ on serum hormone levels and ovarian reproduce-related genes of 93-week-old and 97-week-old laying hens:（1）When laying hens were 93 weeks of age,the interaction between VA and VK₃had significant effects on Progesterone（P）（P<0.05）.When laying hens were 97 weeks old,adding different levels of VA and VK₃ has no significant effect of Estradiol（E₂）and P in serum of laying hens（P>0.05）Different levels of VA and VK₃ supplementation made the E₂ content of laying hens at 97 weeks of age higher than that at 93 weeks of age.（2）Adding 7000 IU/kg VA significantly down-regulated the relative expression of Androgen receptor（AR）m RNA in the ovary of laying hens（P<0.05）.Adding 14000IU/kg VA significantly down-regulated the m RNA relative expression level of Activin A receptor type 1（ACVR1）and up-regulated the m RNA relative expression level of Bone morphogenetic protein 15（BMP15）in the ovaries of laying hens（P<0.05）.Adding 2.0 mg/kg of VK₃ significantly increased ACVR1,Follicle stimulating hormone receptor（FSHR）and Prolactin receptor（PRLR）in ovaries of laying hens（P<0.05）.The interaction between VA and VK₃ significantly down-regulated the m RNA relative expression level of ESR1 in the ovaries of laying hens（P<0.01）.2.Effects of VA and VK₃ on antioxidant function of 97-week-old laying hens:（1）Adding 14000 IU/kg VA extremely significantly increased the content of Malondialdehyde（MDA）,Total Superoxide dismutase（T-SOD）,Catalase（CAT）and Glutathione peroxidase（GSH-Px）in the jejunum of laying hens（P<0.01）;（2）The interaction between VA and VK₃significantly down-regulated the activities of T-SOD and GSH-Px in the ovaries of laying hens（P<0.05）.（3）Adding 7000 and 14000 IU/kg VA significantly reduced the relative expression of GSH-Px3 m RNA in the jejunum of laying hens（P<0.05）.The addition of 2.0 and4.0 mg/kg VK₃ significantly increased the relative expression of SOD-1 and CAT m RNA in the jejunum of laying hens（P<0.05）.The interaction between VA and VK₃significantly affected the m RNA relative expression level of GSH-Px1 in jejunum of laying hens（P<0.05）.（4）Compared with the addition of 0 IU/kg VA,the addition of 7000 and 14000IU/kg VA significantly reduced the relative expression of Nrf2 and GSH-Px1 m RNA in the ovaries of laying hens.The interaction of VA and VK₃ significantly affected the m RNA relative expression level of GSH-Px3 in jejunum of laying hens（P<0.01）.3.Effects of VA and VK₃ on immune function of 97-week-old laying hens:（1）The addition of 7000 IU/kg VA and 14000 IU/kg VA significantly reduced the plasma Ig M content（P<0.05）.The addition of 2.0 mg/kg VK₃ significantly increased the Ig G content in layer plasma.The addition of 4.0 mg/kg VK₃ significantly reduced the Ig M content in layer plasma（P<0.05）.Adding 14000 IU/kg of VA or 4.0 mg/kg of VK₃ both made s Ig A in laying hens jejunum.The content showed a downward trend（P>0.05）.（2）The addition of 14000 IU/kg VA significantly down-regulated the relative expression of IL1-βm RNA in the jejunum of laying hens（P<0.05）.The addition of 4.0mg/kg VK₃ significantly increased the relative expression of p Ig R m RNA in the jejunum of laying hens（P<0.05）.Adding 2.0,4.0 mg/kg of VK₃ increased the relative expression of TNF-αm RNA in the jejunum of laying hens.（P<0.01）.（3）Adding 7000,14000 IU/kg of VA significantly increased the relative expression of IL-8 m RNA in layer spleen（P<0.05）.Adding 14000 IU/kg of VA increased the relative expression of IL-10 m RNA in layer spleen.The amount was significantly reduced（P<0.05）.The interaction of VA and VK₃ significantly down-regulated the relative expression of TNF-αm RNA in the spleen of laying hens（P<0.01）.The above results illustrated that:The results showed that supplementation of 2.0 mg/kg VK₃ promoted the release of E₂ hormone,regulated the m RNA relative expression levels of ACVR1,FSHR and PRLR genes,and maintained a higher laying level of aged laying hens.The supplementation of 7000 and 14000 IU/kg VA increased the activity of antioxidant enzymes in jejunum and decreased the activity of antioxidant enzymes in ovary of aged laying hens.Supplementation of 14000 IU/kg VA did not significantly improve the immune function of aged laying hens,but supplementation of 2.0 and 4.0 mg/kg VK₃increased plasma Ig G level and m RNA relative expression levels of IL-10 and TNF-αgenes in jejunum,respectively.