China Animal Husbandry and Veterinary Medicine ›› 2019, Vol. 46 ›› Issue (12): 3572-3580.doi: 10.16431/j.cnki.1671-7236.2019.12.014

• Animal Nutrition and Feed Science • Previous Articles     Next Articles

Effects of Dietary Iron Addition Levels on Tissue Structure and Iron Content of Immune Organs in Sheep

LIU Xuejie1, LU Jing1, LIAN Huimin1, YUAN Rui1, GAO Xueli1, SUN Haixia2   

  1. 1. Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China;
    2. Northeast Institute of Geography and Agricultural Ecology, Chinese Academy of Sciences, Harbin 150081, China
  • Received:2019-06-28 Online:2019-12-20 Published:2019-12-21

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Abstract: To study the effect of different iron levels in diet on immune function of sheep,and explore the risk of iron overdose during sheep feeding,different doses of FeSO4,including 500,1 000 and 1 500 mg/kg of iron,were added to the basic diet of sheep.After feeding 75 days,immune organs of sheep (spleen,thymus,portal lymph nodes,duodenal lymph nodes and palatine tonsil) were adopted.Organ structures and hemosiderin deposition were observed using traditional pathological methods.The distribution of hemosiderin and iron content in the above organs were measured.The results showed that proportion of splenic white pulp in spleen decreased,the number of lymphocytes reduced and its arrangement was loosed,accompanied by swelling and vacuolization after sheep were fed with excessive iron.Moreover,we found that thymus cortex became thinner,the medulla became thicker and fused,the number of thymus corpuscles decreased and the structure of thymus corpuscles was blurred.The cortical and medullary areas of portal lymph nodes and duodenal lymph nodes became thinner and blurred,the space between cortical lymphatic sinus and medullary sinus increased,and the structure of lymph nodules was blurred.The number of lymph nodules in parenchyma of palatine tonsil decreased,and post capillary venules appear congested.After feeding excessive iron,the iron content in immune organs increased,in which the iron content in spleen was the highest and that in palatine tonsil was the least.The iron content in spleen of low,medium and high iron excess group was extremely significantly higher than that of control group (P<0.01).The results showed that the tissue structure of sheep immune organs was damaged in varying degrees after sheep were fed with excessive iron,and the more iron added in fodder,the damage of tissue structure was more serious.The amount of iron accumulated in each immune organ was positively correlated with iron level added in the diet.Excessive iron intake seriously affects the immune function of sheep.Therefore,in the process of sheep feeding,it is necessary to strictly abide by the NRC (1985) feed standard of the United States,and the iron level in the diet should not exceed 500 mg/kg.

Key words: excessive iron; sheep; immune organs; tissue structure

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