Importance of Vitamin E and Selenium in the Prevention of Bovine Mastitis: A Review
The function of trace minerals including selenium and vitamin E in reproduction and overall animal performance is of considerable economic concern. Supplemental vitamin E and selenium improve immune function of dairy cattle, especially during the peripartum period. An inadequate intake of selenium and vitamin E is related with an increased incidence of retained fetal membranes, mammary gland infections, and abortion. While gross or major deficiencies may not be seen, lesser problems still may be serious in nature. Meeting the needs of vitamin E and selenium along with other trace minerals requires knowledge of animal requirements. Additionally those factors that affect the availability of the needed minerals must also be considered. Aforesaid nutrients on long term basis are required to maintain normal cellular activity, reproductive function, growth development, mammary and claw health. Improving overall nutrient status by feeding highly bioavailable trace minerals , such as complexed minerals (Zn, Se, Cu, Mn), is one way livestock producer can ensure that their cattle have adequate trace mineral status to help maximize health, fertility and productivity.
More than 60% of world buffalo population resides in Asia (Cruz, 2010). Buffaloes are significant milk producer in south and south-west Asia contributing approximately 93.17 % (FAO, 2010). Presently, in India, more than half of the milk comes from buffaloes. Bovine mastitis can be defined as infectious or non infectious inflammation of mammary glands (Bradley, 2002) characterized by physical, chemical and usually bacteriological changes in milk and pathological changes in udder affecting the quantity and quality of milk (Radostits et al., 2000; Sharma et al., 2012). In dairy sector mastitis causes great economic loss of farmers as well as country by reduced milk production upto 70%, treatment coast upto 7%, milk withdrawal after treatment upto 9%, increased labour coast and premature culling upto 14% (Miller et al., 1993). It was estimated that annual economic loss due to mastitis increase from Rs. 529 million/annum in 1992 (Dhanda and Sethi, 1962) upto Rs. 60532 million/annum in 2001 (Dua, 2001). Mastitis is one of the most important diseases in dairy cattle accounting for 38% of the total direct coast of common production disease (Kossaibati and Esslemont, 1997). The periparturient period is characterized by sudden changes in metabolic and immune cell functions that predispose dairy cows to increased incidence of disease (Contreras et al., 2010). The transition phase from pregnancy to lactation is crucial for the profitability of the dairy cow and is characterized by depletion of antioxidant status of animal (Grummer, 1995). Physiological changes during transition period associated with rapid differentiation of secretory parenchyma, intense mammary gland growth, and the onset of copious milk synthesis and secretion are accompanied by a high-energy demand and an increased oxygen requirement (Gitto et al., 2002). Increased oxygen demand during periparturient period stimulates production of oxygen-derived reactants which are known as reactive oxygen species (ROS). When production of ROS become more than its neutralization by antioxidant mechanisms, it leads to oxidative stress (Trevisan et al., 2001). Imunosuppression is very common phenomenon during the transition period and animal become susceptible for number of diseases (Mallard et al., 1998). During transition period different components of the host defense system are altered which includes neutrophils function, lymphocyte responsiveness to mitogen stimulation, antibody responses, and cytokine production by immune cells (Mallard et al., 1998; Kehrli et al., 2006). Impaired neutrophil function prior to parturition may leads to the occurrence of mastitis, metritis, and retained placenta in dairy cows (Cai et al., 1994; Kimura et al., 2002). Oxidative stress leads to peroxidative damage of lipids and other macromolecules of cells with consequent alteration of cell membranes and other cellular components (Toyokuni, 1999). Antioxidants can be defined as any substance that delays, prevents, or removes oxidative damage to target molecules (Halliwell and Gutteridege, 2007) and include some vitamins like vitamin A, vitamin C and vitamin E and some minerals like zinc and copper and several metalloenzymes such as superoxide dismutase, catalase and glutathione peroxidase.
Vitamin E, Se and Mastitis:
Vitamin E and selenium (Se) are key components of the antioxidant system of tissues and cells. Vitamin E is the most important lipid soluble antioxidant and the biologically most active form is α-tocopherol. Vitamin E is an integral component of all lipid membranes and has a role in protecting lipid membranes from attack by high tissue concentrations of reactive oxygen species (Rice and Kennedy, 1988). Most cases of clinical mastitis occur during the first month of lactation (Green et al., 2002), and coincide with the lowest vitamin E blood concentration (Goff and Stabel, 1990). Maintenance of optimal level of vitamin E together with low levels of oxidative stress is an important factor in dry cow management and improvement of udder health. Selenium is an integral component of the enzyme GSH-Px (Diplock, 1981; Erskine, 1993; Smith et al., 1997) which catalyzes the reduction of organic hydroperoxides, lipid peroxides, and hydrogen peroxide, using glutathione as the reducing agent, thereby protecting cells from oxidative damage resulting from normal oxidative metabolism. Blood Se concentration also related with occurrence of clinical mastitis and somatic cell count (SCC). Experiments shown that glutathione peroxidase activity, phagocytic activity and phagocytic index of polymorphonuclear becomes more in the mastitic animal treated with vitamin E and selenium than those treated with antibiotic alone (Mukherjee, 2007). Selenium supplementation to periparturient cows reduces the incidence and severity of mastitis (Smith et al., 1984) because of the actions of certain antioxidant seleniumdependent enzymes (Papp et al., 2007). Plasma glutathione peroxidase is considered as an indicator of oxidative stress (Tüzün et al., 2002). It was also seen in experiments that diets of heifers supplemented with vitamin E and Se from 60 days pre-partum and continuing throughout lactation had significantly fewer infected quarters at calving, reduced prevalence of infection throughout lactation, fewer cases of clinical mastitis, infections of shorter duration, and lower milk SCC compared with the none supplemented heifers (Smith et al., 1985). Minerals (Zinc, copper, iron, manganese, selenium) are essential for the formation of antioxidants’ enzymes. Minerals (Zinc, copper, iron, manganese, selenium) are essential for the formation of antioxidants’ enzymes. Some minerals like copper, zinc, iron and manganese are important component of various antioxidant enzyme systems. For example Zn is an essential part of an enzyme superoxide dismutase (SOD) which removes the superoxide free radical thereby reducing the oxidative stress (Abd Ellah, 2013). SOD is considered the first defense against prooxidants that convert the superoxide to hydrogen peroxide whereas glutathione peroxidase converts hydrogen peroxide into less dangerous reduced forms (Halliwell and Chirico, 1993). Supplementation of zinc helps the animal to recover from increased oxidative stress by reducing the SCC (Kincaid et al., 1984; Popovic, 2004) which may act as a source for free radicals and hence oxidative stress. Experimental studies approved that copper supplementation reduced the severity of clinical signs of E. coli mastitis (Scaletti et al., 2003). Catalase primarily found within peroxisomes of most cells, is an iron metalloenzyme which catalyses the conversion of hydrogen peroxide into water and oxygen (Chance et al., 1979). Plasma level of vitamin A, beta carotene and αtocopherol decreases during periparturient period (Michiels et al., 1994; Weiss et al., 1997; Arechiga et al., 1998). Minerals (Zinc, copper, iron, manganese, selenium) are essential for the formation of antioxidants’ enzymes. From above discussion we can conclude that antioxidants are of prime importance and play very important role in eliminating the free radicals produced during different biochemical reactions inside the body. Since the rate of production of free radicals during periparturient period is very high so it is mandatory to supply the antioxidants either in feed or in injection form.
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