Mamata Joysowal1*, Gunaram Saikia2, Bibeka N. Saikia3 and Robin Bhuyan4
1Assistant professor, 2, 3, 4, Professor, Department of Animal Nutrition, College of Veterinary Science, AAU, Khanapara, Guwahati-781022
*Corresponding author, email: mamtajaiswal525@gmail.com
Role of nano-zinc
Trace elements are minerals that are present in very low concentrations in the human body and yet are crucial for a wide range of physiological functions. Zinc, the second most abundant trace element, is obtained primarily from the diet (Lim et al., 2013; Maret et al., 2016). After being taken up in the intestine, zinc is distributed to various target organs, where it plays key roles in processes such as immunity, protein folding, apoptosis, and antioxidant activity (Sugimoto et al., 2023). With the rise in demand for high-quality poultry feed, poultry farmers and feed manufacturers are always on the lookout for poultry health and growth promoters. Zinc is vital for the proliferation of cells and their differentiation. Several enzymes are associated with zinc minerals like carbonic anhydrases, pancreatic carboxy – peptidase, lactate dehydrogenase, alcohol dehydrogenase, alkaline phosphatase and thymidine kinase and one important enzyme carbonic anhydrase was identified and purified in 1940, which contains a metalloenzyme zinc at 0.33%, which catalyzes the breakdown of carbonic acid into CO2 and H2O.
Physiological functions of zinc:
Zinc (Zn), an essential trace element for poultry, plays a crucial role in promoting growth, improving feed conversion efficiency, enhancing antioxidant activity, and preventing disease (Hu et al., 2024). Being a component of carbonic anhydrases, zinc facilitates the transport of CO2 from tissues to lungs. Zinc is an essential component of both DNA and RNA polymerase enzymes. Zinc has been found cofactor in more than 300 metallo-enzymes, which are essential for enzyme structure, bone development and growth. It is involved in cell replication and differentiation, particularly nucleic acid metabolism (McDonald, 2002).
Fig. 1. The roles of zinc in human physiology. Some of the most important functions of zinc in the human body include supporting a healthy immune response by promoting differentiation of naive T cells into activated Th17 cells, facilitating proper folding and activity of zinc-containing proteins, acting as a cofactor for superoxide dismutase (SOD) to exert antioxidant activity, and modulating the stability and activity of p53 to regulate apoptosis.
SOD, superoxide dismutase; Th17, T helper 17.
References: “Protein folding” representative image from Neuhaus (2022), Yildiz et al. (2019), Maria et al. (2013).
It is vital to the activity of a variety of hormones, including glucagon, insulin, growth hormone, and the sex hormones. It also plays a key role in the immune system. Consumers, producers, Poultry feed manufacturers and others related to the poultry industry have developed a good interest in the role of zinc in poultry nutrition. Zinc is distributed to various target organs throughout the body, with concentrations tending to be highest in bone and muscle, followed by the skin and liver (Trame et al., 2018).
Zinc as an antioxidant:
Zinc is an indispensable part of the antioxidant system in animals. Antioxidants combat ‘reactive oxygen species’ (ROS) and protect the body from the harmful effects of ROS in various ways. Zinc is a major part of the antioxidant enzyme superoxide dismutase (SOD), which helps defend the body against ROS by converting superoxide anions into hydrogen peroxide. Zinc reduces oxidative stress by antagonism of the redox-active transition metals (inorganic copper and iron), preventing the formation of hydroxyl radicals from hydrogen peroxide (H2O2). Zinc interferes in the Fenton reaction by competing with the binding sites of transition metals (iron, copper, and zinc), serving as a donor of electrons for such reactions.
Zinc appears to indirectly suppress oxidant stress by the stimulation of certain substances which have antioxidant properties. It affects in two ways: acutely and chronically. The acute effects of Zn include antagonism to redox-active transition metals and protection of protein sulfhydryl groups, while chronic effects involve indirect protection from pro-oxidants due to the induction of other substances, such as metallothionein, which are cysteine-rich proteins that serve as antioxidants by scavenging reactive oxygen species (ROS). Zinc-dependent metallothionein are found in different forms in animals, especially in the pancreas, liver, intestine, and kidney of chickens, where it serves as an antioxidant in these tissues (McClure, 2008) and, under different conditions of oxidative stress such as toxicity of certain drugs, they prevent oxidative DNA damage and mutagenesis and ethanol toxicity.
Conclusions
Supplementation of high dietary Zn in chicken results in elevated levels of Zn in the liver, kidney, pancreas, spleen, and gizzard. Dietary Zn supplementation has an inverse relationship with Fe and Cu content of the liver in laying hens, while the copper content of the liver, pancreas and gizzard decreased with increasing Zn supplementation in the feed.
References:
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