Alleviating Effects of Supplemental Chitosan in Drinking Water on Egg Quality,Serum Antioxidant Indices,Liver Injury and Oviduct Inflammation of Laying Hens Challenged with Salmonella pullorum
This study was conducted to investigate the alleviating effects of supplemental chitosan(CS)in drink-ing water on egg quality,serum antioxidant indices,liver injury and oviduct inflammation of laying hens chal-lenged with Salmonella pullorum(SP).A total of 180 healthy Hy-Line brown laying hens of 35-week-old with similar body weight and laying rate were randomly divided into 3 groups with 5 replicates per group and 12 hens per replicate.Hens in the three groups,control group(CON group),challenge group(SP group)and chitosan group(CS group),were fed the same basal diet.The experiment lasted for 7 days.On day 1 of the experiment,each chicken in SP group and CS group was given 1 mL SP bacterial solution with a viable bacterial count of lx 109 CFU/mL orally,and each chicken in CON group was given 1 mL normal saline orally at 09:00 and 17:00,respectively.After the second challenge,0.4％ CS was supplemented to the drinking water in CS group immedi-ately,and the CS containing water was taken for 7 consecutive days.The results showed as follows:1)com-pared with CON group,the laying rate in SP group was significantly decreased(P＜0.05),the glutamic oxalace-tic transaminase(AST)activity and contents of albumin(ALB)and malondialdehyde(MDA)in serum were significantly increased(P＜0.05),the contents of interleukin-1p(IL-1p)and SP antibody(SP-Ab)in plasma were significantly increased(P＜0.05),and the contents of interleukin-6(IL-6)and tumor necrosis factor-α(TNF-α)in plasma were significantly decreased(P＜0.05);on days 1 and 3 after SP challenge,the eggshell strength in SP group was significantly decreased(P＜0.05).Typical clinical symptoms such as white dysentery,lethargy and poor mental state of laying hens were observed in SP group.Histopathological observations showed significant pathological changes such as fragmented chorionic membrane in the oviduct magnum tissues,multiple inflammatory infiltrative lesions and steatosis,as well as a small amount of hepatocyte necrosis,disintegration and nuclear pyknosis.2)Compared with SP group,the laying rate in CS group was significantly increased(P＜0.05),the AST activity and MDA content in serum were significantly decreased(P＜0.05),the liver index and activities of glutathione peroxidase(GSH-Px)and superoxide dismutase(SOD)in serum as well as the SP-Ab content in plasma were significantly increased(P＜0.05);on days 3 and 7 after supplementing CS to drinking water,the eggshell strength in CS group was significantly increased(P＜0.05).The clinical symptoms of laying hens in SP group were alleviated,and pathological observations showed that the damage to oviduct magnum and liver was alleviated.3)Compared with CON group,the laying rate in CS group had no significant difference(P＞0.05),the liver index,contents of ALB and total protein(TP)in serum,activities of GSH-Px and SOD in serum and SP-Ab content in plasma were significantly increased(P＜0.05),and the IL-6 content in plasma was significantly decreased(P＜0.05).In conclusion,the supplementation of 0.4％ CS in drinking water can alleviate SP infection and the resulting decline in laying performance and egg quality by reducing liver injury and oviduct inflammation,enhancing antioxidant function and regulating immune inflammatory response of laying hens.[Chi-nese Journal of Animal Nutrition,2024,36(1):267-278]
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