Effects of Common Mineral Trace Elements on Immune Function of Livestock and Poultry

Li Hu,Ning’an Mei,Yuping Yan,Jianming Ruan

1.Feed Workstation of Ningxia Hui Autonomous Region,Yinchuan 750002,China;2.Institute of Animal Husbandry and Veterinary Medicine(Co.,Ltd.)of Ningxia Academy of Agricultural and Forestry Sciences,Yinchuan 750002,China

Abstract The effects of zinc(Zn),iron(Fe),selenium(Se),copper(Cu),manganese(Mn),chromium(Cr)and germanium(Ge)on immune function of livestock and poultry are discussed,in order to provide the reference for safe and reasonable use of trace elements.

Keywords Minerals;Trace elements;Livestock and poultry;Immune function

As indispensable nutrients of livestock and poultry,mineral trace elements are closely related to immunity,which directly involves in cellular and humoral immunity of livestock and poultry,and affects the specific and non-specific immune functions of livestock and poultry.It plays an important role in maintaining the structure and function of central immune organs and peripheral immune organs of livestock and poultry,thereby reducing the occurrence of diseases and ensuring the healthy growth of livestock and poultry.However,excessive use of mineral trace elements also has the opposite effect,and even causes harm.In this paper,the effects of Zn,Fe,Se,Cu,Mn,Cr and Ge on immune functions of livestock and poultry are discussed,in order to provide some references for safe and reasonable use of trace elements.

1 Zinc(Zn)

1.1 Effect Zn directly involves in the synthesis and metabolism of protein and nucleic acid,energy metabolism,cellular immunity and humoral immunity.Zn plays an important role in maintaining the structure and function of central immune organs(thymus,bursa fabricius)and peripheral immune organs(lymph node,spleen,tonsil).Insufficient Zn content in livestock and poultry not only affects the growth and development,but also leads to atrophy of immune organs,low immune function,and easy infection of diseases.After Zn supplementation,the siutation is significantly improved.

1.2 Harms of Zn deficiency The common characteristics of Zn deficiency in livestock and poultry are slow growth and development,and atrophy of immune organs(the weight loss of mesentery,lymph nodes,spleen,thymus and other immune organs reach 20%-40%),and immune system is suppressed.Zn deficiency will inhibit the proliferation and differentiation of T cells,thus causing functional damage of T cells and damaging the normal synthesis of RNA and protein in immune cells.Zn can increase the immune function of B cells and enhance the synthesis of immunoglobulin in pigs and chickens.Immunoglobulin in Zn-deficient chickens does not show normal antibody serum albumin reactivity,and the number of lymphoid tissue and lymphocytes is significantly reduced.The number of T cells decreases in infection of sheep foot rot disease.

1.3 Harms of Zn excess Excessive Zn will reduce the content of DNA,RNA and protein in T and B lymphocytes of thymus,bone marrow and spleen,decrease the ability of cell proliferation,and lessen the phagocytosis and bactericidal ability of peripheral blood granulocytes and peritoneal macrophages.

1.4 Nutritional requirement and maximum safety level Zn requirements are:chicken 50-60 mg/kg,pigs 50-80 mg/kg,cattle 50-100 mg/kg,sheep 50-60 mg/kg.The maximum safety levels of Zn are:chicken 1 000 mg/kg,pigs 1 000 mg/kg,cattle 400 mg/kg,sheep 300 mg/kg.

2 Iron(Fe)

2.1 Effect Fe is a component of many enzymes and hemoglobin in the body,and Fe deficiency or excess can cause damage to the immune system.In the early stage of bacterial or viral infection,the serum Fe content decreases,but the serum Fe content rises rapidly when animals are restored to health.

2.2 Harms of Fe deficiency Fe deficiency has an impact on cellular immune function.Schmidt et al.reported that Fe deficiency led to not only impaired cellular immunity,but also impaired lymphocyte transformation and decreased macrophage migration inhibitory factor.Fe deficiency can interfere with the action of ferriferase,so that the activity of phagocytes is impaired,resulting in reduced lethality.Fe deficiency anemia reduces the response of external lymphocytes to various mitogens or antigens.Fe deficiency during preg-nancy and lactation period can lead to humoral immunity damage for a long time in the offspring.Supplementation for three weeks after weaning can not normalize the existing injury.The bactericidal ability of neutrophils in Fe-deficient livestock and poultry decreases.

2.3 Harms of Fe excess Excess Fe will inhibit the bactericidal activity of leukocytes,reduce the bacteriostatic effect of ferritin and lactoferrin,and increase the incidence and severity of infection.

2.4 Nutritional requirement and maximum safety level Fe requirements are:chicken 40-80 mg/kg,pigs 50-120 mg/kg,cattle 40-60 mg/kg,sheep 30-40 mg/kg.The maximum safety levels of Fe are:chicken 1 000 mg/kg,pigs 3 000 mg/kg,cattle 1 000 mg/kg,sheep 500 mg/kg.

3 Selenium(Se)

3.1 Effect Berenshtein reported for the first time that Se enhanced the humoral immunity of livestock and poultry,and studied the carcinogenic effect of Se.The results indicated that Se significantly prevented the tumors induced by chemical substances and viruses by inhibiting the metabolic activity of carcinogens,and had anti-tumor effect.When 0.2 mg/kg Se was supplemented in diets of calves and lambs,and calves and lambs were inoculated with bovine infectious bronchitis spot and parainfluenza virus vaccine,the serum IgM concentration and antibody titer were significantly increased.

3.2 Harms of Se deficiency When Se is deficient,both cellular and humoral immunity are affected,resulting in reduced B lymphocyte,damaged T cell-mediated immunity,decreased bactericidal activity of neutrophils.Furthermore,the cell and humoral immune mechanism is damaged,thereby reducing the resistance to infection.Boyre et al.reported that dietary Se deficiency significantly affected non-specific immune function of livestock and poultry.

Se is known as an immune booster for pigs,poultry and ruminants and is often added together with vitamin E,because they have similar physiological effects and are additive to the immune system.

3.3 Nutritional requirement and maximum safety level Se requirements are:chicken 0.1-0.2 mg/kg,pigs 0.1-0.2 mg/kg,cattle 0.1-0.2 mg/kg,sheep 0.1-0.2 mg/kg.The maximum safety levels of Se are:chicken 4 mg/kg,pigs 4 mg/kg,cattle 3 mg/kg,sheep 3 mg/kg.

4 Copper(Cu)

4.1 Effect Cu plays an important role in regulating the immune function of the body.As a prothetic group of a series of enzymes in livestock and poultry(such as superoxide dismutase,cytochrome c oxidase and plasma ceruloplasmin),Cu plays an important role in regulating the biological activities of these enzymes.Cu forms the body’s defense system through its enzymes,so as to increase the anti-inflammatory and antioxidant properties of cells,and enhance the body’s immune function.It has different effects on cellular immunity,humoral immunity,anti-infection and anti-tumor,etc.When Cu is deficient,the immune function of livestock and poultry is impaired,which is manifested as thymus atrophy,reduced immune cell activity and response to mitogen stimulation,impaired antibody synthesis and reduced antibody titer.

The phagocytosis ability of polymorphonuclear leucocyte in sheep fed low-Cu diet was decreased,but the phagocytosis ability was significantly increased after Cu supplementation.Wu reported that Cu deficiency or excess would lead to growth inhibition,immune organ atrophy,and reduced lymphocyte activity in broilers.

4.2 Nutritional requirement and maximum safety level Cu requirements are:chicken 3-4 mg/kg,pigs 10-15 mg/kg,cattle 5-15 mg/kg,sheep 5-6 mg/kg.The maximum safety levels of Cu are:chicken 300 mg/kg,pigs 250 mg/kg,cattle 100 mg/kg,sheep 15 mg/kg.

5 Manganese(Mn)

5.1 Effect A large number of studies have shown that Mn at certain dose can stimulate the cell proliferation of immune organs,thus enhancing the cellular immune function.Mn also increases the level of interferon(INF)in the body,thus enhancing the phagocytic capacity of macrophages.Low concentration of Mn is an essential element in lymphocyte proliferation,while high concentration of Mn will compete with Ca and further inhibit cell proliferation.It has been found that Mn appears to selectively affect the T cell proliferation response and has little effect on B cell proliferative response.

5.2 Nutritional requirement and maximum safety level Mn requirements are:chicken 40-60 mg/kg,pigs 30-50 mg/kg,cattle 40-100 mg/kg,sheep 30-40 mg/kg.The maximum safety levels of Mn are:chicken 1 000 mg/kg,pigs 400 mg/kg,cattle 1 000 mg/kg,sheep 1 000 mg/kg.

6 Chromium(Cr)

Cr can fight stress and improve immunity.Stress will increase serum cortisol levels,and glucocorticoids are steroids that inhibit growth and immune system function.Stress increases the loss of Zn,Cu,Fe,Cr and other trace elements in the body,and Cr can avoid the loss of trace elements such as Zn,Cu,Fe and Mn by reducing serum cortisol concentration of livestock and poultry,and enhance the immunity of livestock and poultry by increasing the content of immunoglobulin and antibody titer.

Cr supplementation can increase the level of serum immunoglobulin,decrease rectal temperature and increase the antiserum titer of injected red blood cells.The effect of Cr on immune function depends on the supplemental form.When Keyley et al.added 400 mg/kg Cr to the diet of cattle,and high chromium yeast and chromium nicotinate showed the highest responses to subcutaneous phytothrombin(PHA),while chromium oxide did not have such reaction.When Chung et al.studied the relationship between Cr and immunity,they found that Cr would affect the immune function when the diet was added with soybean meal,which was ineffective if soybean meal was not added.Therefore,the effect of Cr can only be effective under certain dietary nutrient levels.

7 Germanium(Ge)

Mizushima et al.reported that the use of Ge-132 (and B-carboxyethyl germanium sesquioxide)increased the formation of immature cells induced by Caglidnin A.Chen et al.reported that Ge-132 had significant inhibitory effects on the occurrence and development of MDV(Marek’s disease virus)and its tumor lesions in chickens.Ge-132 obviously enhanced the T lymphocyte transformation rate of chicks artificially inoculated with MDV.Tang et al.showed that the weight gain of immune organs of Ge-rich chicks was significantly faster than that of common chicks after 30 days of age,the thymus index,bursa of Fabricius index and spleen index were significantly higher than that of common chickens(P＜0.05),and the incidence and mortality of Ge-rich chicks were significantly lower than that of common chickens(P＜0.05).Li et al.showed that Ge enhanced the ability of B lymphocytes to produce antibodies,activated NK cells and macrophages,and stimulated the production of IL-2 in peripheral blood to a certain extent.

8 Conclusions

In conclusion,trace elements play an extremely important role in regulating the immune function of the body,and have a positive impact on the specific and nonspecific immunity of livestock and poultry.To a certain extent,they can enhance the immunity of livestock and poultry,thus improving their resistance to diseases.Livestock and poultry are an organic whole,and trace elements have synergistic and antagonistic effects,and are affected by a variety of factors.Therefore,the influence of trace elements on the immune response of livestock and poultry is not single and unchanged,but the result of constant adjustment of various factors.

Currently,there are still some questions troubling us,such as the deeper mechanism of the effect of trace elements on immune function;synergistic effects of trace elements on the immune system.We need to continue to comprehensively apply the knowledge of molecular biology,molecular immunology and other disciplines to further explore and solve these problems.