The uptake, bioaccumulation, biotransformation, and risks of nanomaterials (NMs) for food crops are still not well understood. Very few NMs and plant species have been studied, mainly at the very early growth stages of the plants. Most of the studies, except one with multiwalled carbon nanotubes performed on the model plant Arabidopsis thaliana and another with ZnO nanoparticles (NPs) on ryegrass, reported the effect of NMs on seed germination or 15-day-old seedlings. Very few references describe the biotransformation of NMs in food crops, and the possible transmission of the NMs to the next generation of plants exposed to NMs is unknown. The possible biomagnification of NPs in the food chain is also unknown.

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Interaction of nanoparticles with edible plants and their possible implications in the food chain

Selenium ( Se 34 79 ) is a metalloid which is close to sulfur (S) in terms of properties The Se concentration in soil varies with type, texture and organic matter content of the soil and with rainfall Its assimilation by plants is influenced by the physico-chemical properties of the soil (redox status, pH and microbial activity) The presence of Se in the atmosphere is linked to natural and anthropogenic activities Selenoproteins, in which selenium is present as selenocysteine, present an important role in many body functions, such as antioxidant defense and the formation of thyroid hormones Some selenoprotein metabolites play a role in cancer prevention In the immune system, selenium stimulates antibody formation and activity of helper T cells, cytotoxic T cells and Natural Killer (NK) cells The mechanisms of intestinal absorption of selenium differ depending on the chemical form of the element Selenium is mainly absorbed in the duodenum and caecum by active transport through a sodium pump The recommended daily intake of selenium varies from 60 μg/day for women, to 70 μg/day for men In growing ruminants the requirements are estimated at 100 μg/kg dry matter and 200 μg/Kg for pregnant or lactating females A deficiency can cause reproductive disorders in humans and animals

Selenium in the Environment, Metabolism and Involvement in Body Functions

Mesoporous silica based novel conjugate adsorbent for efficient selenium(IV) detection and removal from water

Selenium is an essential trace element important for many physiological processes, especially for the functions of immune and reproductive systems, metabolism of thyroid hormones, as well as antioxidant defense. Selenium deficiency is usually manifested by an increased incidence of retention of placenta, metritis, mastitis, aborts, lowering fertility and increased susceptibility to infections. In calves, lambs and kids, the selenium deficiency demonstrates by WMD (white muscle disease), in foals and donkey foals, it is associated with incidence of WMD and yellow fat disease, and in pigs it causes VESD (vitamin E/selenium deficiency) syndrome. The prevention of these health disorders can be achieved by an adequate selenium supplementation to the diet. The review summarizes the survey of knowledge on selenium, its biological significance in the organism, the impact of its deficiency in mammalian livestock (comparison of ruminants vs. non-ruminants, herbivore vs. omnivore) and possibilities of its peroral administration. The databases employed were as follows: Web of Science, PubMed, MEDLINE and Google Scholar.

https://www.mdpi.com/1422-0067/18/10/2209/pdf

A Summary of New Findings on the Biological Effects of Selenium in Selected Animal Species-A Critical Review.

This review article examines the role of selenium (Se) and the effects of Se supplementation especially in the bovine species. Selenium is an important trace element in cattle. Some of its roles include the participation in the antioxidant defense the cattle farms. The nutritional requirements of Se in cattle are estimated at 100 μg/kg DM (dry matter) for beef cattle and at 300 μg/kg DM for dairy cows. The rations high in fermentable carbohydrates, nitrates, sulfates, calcium or hydrogen cyanide negatively influence the organism’s use of the selenium contained in the diet. The Se supplementation may reduce the incidence of metritis and ovarian cysts during the postpartum period. The increase in fertility when adding Se is attributed to the reduction of the embryonic death during the first month of gestation. A use of organic Se in feed would provide a better transfer of Se in calves relative to mineral Se supplementation. The addition of Se yeasts in the foodstuffs of cows significantly increases the Se content and the percentage of polyunsaturated fatty acids (PUFA) in milk compared to the addition of sodium selenite. The enzyme 5-iodothyronine deiodinase is a seleno-dependent selenoprotein. It is one of the last proteins to be affected in the event of Se deficiency. This delay in response could explain the fact that several studies did not show the effect of Se supplementation on growth and weight gain of calves. Enrichment of Se in the diet did not significantly affect the slaughter weight and carcass yield of bulls. The impact and results of Se supplementation in cattle depend on physiological stage, Se status of animals, type and content of Se and types of Se administration. Further studies in Se supplementation should investigate the speciation of Se in food and yeasts, as well as understanding their metabolism and absorption. This constitute a path to exploit in order to explain certain different effects of Se.

https://www.mdpi.com/1420-3049/21/4/545/pdf

Selenium in Cattle: A Review

The importance of selenium and the effects of its deficiency in animal health

El selenio (Se) es un mineral esencial en la nutricion animal y se considera su participacion en diversos procesos asociados a la produccion animal, tan diversos como la fertilidad de la especie y la prevencion de enfermedades. La glutation-peroxidasa (GSH-Px), fue la primera enzima en que se demostro la presencia activa del selenio y su importancia al evitar el dano oxidativo de las membranas celulares. Con anterioridad se habia demostrado que la conocida como “Enfermedad del musculo blanco” era consecuencia de la deficiencia de Se, determinando muerte en animales recien nacidos y ocasionalmente en animales en desarrollo y aun en adultos, en particular en rumiantes. Actualmente ha quedado claro que el Se tambien es critico en la estructuracion de las enzimas necesarias para la sintesis de la hormona tiroidea y para su activacion en los tejidos perifericos, pasando de T4 a T3. La deficiencia de Se afecta seriamente la capacidad de respuesta inmune de los animales. El diagnostico de la deficiencia debe fundamentarse en los niveles del elemento en los suelos, las plantas forrajeras y la condicion del animal en sangre y tejidos. Se han instrumentado diversas formas de suplementacion del elemento que pueden emplearse dependiendo de las condiciones productivas de los animales y sus niveles previos de Se. La intoxicacion por Se (Selenosis) debe tenerse en cuenta en los programas de suplementacion, y puede ocurrir en formas cronicas o agudas. Las formas cronicas ocurren en regiones con suelos ricos en el elemento y condiciones que favorecen su absorcion por las plantas forrajeras. Las formas agudas generalmente ocurren por excesos del elemento en las dietas o las sales que se administran a los animales o por errores de dosificacion en las formulaciones parenterales. La relacion metabolica del Se entre la hembra gestante, el feto y el recien nacido, es un area que requiere mayor investigacion.

“Selenio y salud animal” Importancia, deficiencia, suplementación y toxicidad

Selenium (Se) is an essential trace element for animal nutrition and plays multiple actions related to animal production, fertility and prevention of diseases. Glutathione peroxidase enzyme (GSH-Px) was the first selenoenzyme to demonstrate the active presence of selenium and its importance to prevent cellular membrane oxidative damage. Formerly, White muscle disease (WMD) was recognized as resulting from Se deficiency, determining new born mortality and adult animals, especially in ruminants. Nowadays, it is clear that Se is critical for thyroid hormone synthesis and its activation in peripheral tissues – from T3 to T4. Lack of Se seriously affects the capacity of immune response by the animals. Se status in the soil, plants, animal blood and tissues can be used as a tool to diagnose Se deficiency. Several forms of Se supplementation are described which can be applied depending of the productive capacity of the animals and their previous levels of Se. Acute and chronic Se intoxication (Selenosis) should be considered in supplementation programs as it may occur in a chronic or acute way. Chronic forms are associated to regional seleniferous soils, with permanent or repeated consumption of seleniferous plants. Acute forms are associated with high ingestion of Se as a result of wrongly designed diets, salt provided to the animals or parenteral injection dosage mistakes. The metabolic relation among Se, the fetus, the newborn and the pregnant dam requires further investigations.

Abd Elghany Hefnawy

Papers

The importance of selenium and the effects of its deficiency in animal health

“Selenio y salud animal” Importancia, deficiencia, suplementación y toxicidad

“Selênio e saúde animal” - importância, deficiência, suplementação e toxidez