Effects Of Garcinol Supplementation On Performance,Immune Function And Intestinal Health Of Late Laying Hens

During the late laying period,rapidly declined egg production performance and poor egg quality have seriously reduced the economic benefits,which are the key obstacle to be solved to improve the economic benefits of laying hens breeding.Garcinol,an antioxidant polyphenol plant extract,has been reported to demonstrate positive effects,including anti-inflammatory,antioxidant and antibacterial.This present study was conducted to investigate the effects of dietary supplementation with garcinol on production performance,egg quality,immune performance,antioxidant capacity and intestinal health of laying hens in late laying period and explore the appropriate dosage of garcinol doses.A total of 144 healthy 57-week-old Jingfen pink-shell hens were selected and randomly divided into four groups: Con group(the maize and soybean meal basic diet),LG group(basic diet with 100 mg/kg of garcinol addition),MG group(basic diet with 300 mg/kg of garcinol addition),and HG group(basic diet with 500 mg/kg of garcinol addition),other feeding conditions were consistent,with 12 replicates per group and 3 hens in each replicate.The test period was 2 weeks for the pre-test and 12 weeks for the test.The production performance and egg quality were counted every week,and blood collection and intestinal samples were collected after the experiment.The main results were as follows:(1)The production performance showed that part levels of garcinol had a tendency to increase the egg production(P=0.051)in the pre-test period(1 to 4 weeks).In the middle of the test(5 to 8 weeks)and the later stage of the experiment(9 to 12 weeks),the average egg weight was significantly reduced due to the addition of garcinol(P<0.05),but there was no significant effect on ADFI and feed-egg ratio(P>0.05).During the whole period of the experiment,the addition of garcinol in the diet tended to increase egg production(P=0.080),and the MG group increased egg production by 2.84%,respectively;while average egg weight was significantly lower(P<0.05).(2)Egg quality: Up to week 4,dietary garcinol supplementation had no significant influence on egg quality.Up to week 8,compared with basic diet group,MG group albumen height and Haugh unit were significantly increased(P<0.05),and LG group could significantly increase the egg shape index(P<0.05).Up to week 12,adding garcinol to the diet could significantly increase albumen height and Haugh unit(P<0.01).Nevertheless,the egg shell brightness(L*)of LG and MG groups was significantly lower than control group(P<0.01)and yellowness(b*)showed a significant decrease(P<0.05).significantly higher than that of group A.(3)Antioxidant ability: Compared with the control group,MG group significantly increased the levels of T-SOD and CAT in serum(P<0.05).The levels of T-AOC in serum increased significantly(P<0.05)with increasing levels of garcinol added to the diets.Furthermore,MG and HG groups could significantly reduce MDA content in serum(P<0.05).(4)Immunity: The laying hens of MG group had lower concentration of IL-2 and IL-6(P<0.05)and a higher level of Ig A(P<0.01)in serum compared with other groups.Moreover,MG and HG groups significantly decreased the levels of LPS and D-lactate in serum compared to the control group(P<0.05).In addition,there was no significant effect of dietary garcinol on the serum levels of Ig G,Ig M,TNF-α and CORT(P>0.05).(5)Intestinal morphology show that dietary supplementation of garcinol increased the villus height of jejunum and ileum(P<0.05),and decreased the crypt depth of jejunum and ileum(P<0.05).Moreover,the effect of MG group was significantly better than that other groups.Then the villus length to crypt depth(V/C)of duodenum,jejunum,ileum in dietary garcinol supplementation group was increased,among which MG and HG groups significantly increased(P<0.01).(6)Gene expression of tight junctions: Dietary garcinol significantly increased Occludin expression compared to the control group(P<0.05);the m RNA abundance of Claudine-2 was significantly upregulated in LG ang MG groups(P<0.05).In contrast,the m RNA expression of Zo-1 was observed no significant difference among the four groups(P>0.05).(7)The 16 S sequencing of the cecum flora showed the addition of garcinol significantly increased the alpha diversity compared with the control group.At the phylum level,the relative abundance of the Firmicutes phylum increased in LG and MG groups,the relative abundance of the phylum Bacteroidota decreased,and the ratio of the phylum Firmicutes to the phylum Bacteroidota increased;at the genus level,the relative abundance of Lactobacillus decreased in the LG and MG groups,but the relative abundance of two intestinal beneficial bacteria,Romboutsia and Rumincoccus-torquesgroup,increased.While a total of 13 marker differential microorganisms were identified from the cecum flora,there were seven differential microbial species in the MG group,with Peptostreptococcales-Tissierellales and Deferribacterota as the most influential differential bacteria.In conclusion,garcinol played crucial roles in improving the production performance and egg quality of laying hens during the late period;enhancing immune function,increasing the antioxidant capacity of body;maintaining the balance of the cecum flora and intestinal barrier.Under the conditions of this study,the MG group(300mg/kg dosage)had the better effect.