Organic or Inorganic Zinc for Laying Hens? A Systematic Review and Meta-analysis of the Effects of Zinc Sources on Laying Performance, Egg Quality, and Zinc Excretion

The higher availability of zinc (Zn) from organic than inorganic sources is already established, but more assertive and cost-friendly protocols on the total replacement of inorganic with organic Zn sources for laying hens still need to be developed. Because some discrepancy in the effects of this replacement in laying hen diets is noticeable in the literature, the objective of this meta-analysis was to properly quantify the effect size of total replacing inorganic Zn with organic Zn in the diet of laying hens on their laying performance, egg quality, and Zn excretion. A total of 2340 results were retrieved from Pubmed, Scielo, Scopus, WOS, and Science Direct databases. Of these, 18 primary studies met all the eligibility criteria and were included in this meta-analysis. Overall, the replacement of inorganic Zn with organic Zn, regardless of other factors, improved (p < 0.01) egg production by 1.46%, eggshell thickness by 0.01 mm, and eggshell resistance by 0.11 kgf/cm2. Positive results of the same nutritional strategy on egg weight and Zn excretion were only observed at specific conditions, especially when organic Zn was supplemented alone in the feed, not combined with other organic minerals. Therefore, there is evidence in the literature that the total replacement of inorganic Zn with organic Zn improves egg production, eggshell thickness, and eggshell resistance. Factors such as hen age and genetics, organic Zn source, concentration of Zn in the feed, and the strategy of its supplementation have to be more carefully considered in protocols designed to address egg weight and Zn excretion by the hen.

Biofortification of Plant- and Animal-Based Foods in Limiting the Problem of Microelement Deficiencies-A Narrative Review

With a burgeoning global population, meeting the demand for increased food production presents challenges, particularly concerning mineral deficiencies in diets. Micronutrient shortages like iron, iodine, zinc, selenium, and magnesium carry severe health implications, especially in developing nations. Biofortification of plants and plant products emerges as a promising remedy to enhance micronutrient levels in food. Utilizing agronomic biofortification, conventional plant breeding, and genetic engineering yields raw materials with heightened micronutrient contents and improved bioavailability. A similar strategy extends to animal-derived foods by fortifying eggs, meat, and dairy products with micronutrients. Employing "dual" biofortification, utilizing previously enriched plant materials as a micronutrient source for livestock, proves an innovative solution. Amid biofortification research, conducting in vitro and in vivo experiments is essential to assess the bioactivity of micronutrients from enriched materials, emphasizing digestibility, bioavailability, and safety. Mineral deficiencies in human diets present a significant health challenge. Biofortification of plants and animal products emerges as a promising approach to alleviate micronutrient deficiencies, necessitating further research into the utilization of biofortified raw materials in the human diet, with a focus on bioavailability, digestibility, and safety.

Stevia (Stevia rebaudiana) Improves Carotenoid Content in Eggs When Fed to Laying Hens

Stevia rebaudiana Bertoni is a shrub with leaves that have a high concentration of carotenoids such as lutein and zeaxanthin. Egg yolks are a bioavailable source of lutein and zeaxanthin. The consumption of these carotenoids has been linked with improved human health. To investigate the impact of dried stevia leaves at 0%, 1% and 2% on the quality variables, the chemical composition and antioxidant content of eggs, the experiment involved 90 Hy-Line Brown laying hens, housed in 30 enriched layer cages, in groups of three from 22 to 26 weeks of age. The impact on the internal qualities of stored eggs was also examined. Yolks from hens fed stevia had an enriched color compared with the controls. At the end of the experiment, the whole egg, without shell, of birds fed 2% stevia had a higher total carotenoid content (p < 0.001) compared with birds fed 1% and 0% stevia, i.e., 5.16 (µg/g), 4.23 (µg/g) and 2.96 (µg/g), respectively. Storage reduced albumen height and increased albumen pH (p < 0.001). Stevia supplementation did not interact (p > 0.05) with storage time among the egg quality variables. Consuming eggs from hens fed stevia may increase carotenoids in human diet.

Valorization of postextraction residues-analysis of the influence of new feed additives with micronutrients on eggs quality parameters

This paper presents attempts to enrich hens eggs with ions of copper, manganese, and zinc through the use of new feed additives (19 mg Cu²⁺; 124 mg Mn²⁺ and 85 mg Zn²⁺) such as biomass of alfalfa and goldenrod after extraction with supercritical carbon dioxide enriched with microelements via biosorption. Mechanical parameters of eggs (shell thickness and strength, Haugh unite), hen's laying performance, microelements content in albumen and yolk were examined and the transfer factor from feed to eggs was determined. The highest transfer of microelements content in albumen occurred in the group of hens fed with enriched goldenrod in a 100% dose (daily dose of microelements from biomass; Cu²⁺ 106%; Mn²⁺ 104%; Zn²⁺ 104% more in comparison to the inorganic salt group), while the highest yolk enrichment with microelements manifested itself for hens fed with enriched goldenrod in a 50% dose (daily dose of microelements from biomass; Cu²⁺ 32%; Zn²⁺ 22% more in comparison to the inorganic salt group). These groups also had the highest total microelements concentration. Mechanical properties of eggs varied insignificantly during the trial. Production parameters did not differ statistically among all experimental group. Eggs produced with need additives had better organoleptic parameters than fed with conventional premixes, which is why they were preferred by the respondents. The presented technology allows obtaining low-cost feed materials characterized by high bioavailability of components. The produced feed additives can serve as potential material for biofortification of eggs with nutrients.

Biosorption as a method of biowaste valorization to feed additives: RSM optimization

The aim of this work was to prepare an innovative microelemental feed additive for laying hens, based on waste biomass from the agricultural sector (alfalfa and goldenrod after CO₂ extraction in supercritical state). The process was optimized by Response Surface Methodology (RSM) and the most favourable enrichment conditions were selected for Cu(II), Mn(II) and Zn(II) ions: pH - 5, sorbate concentration of Cu(II), Mn(II), Zn(II) - 10.0 mg/L for alfalfa and 10.7 mg/L for goldenrod and biomass dose - 0.1 g/L. Physicochemical properties of biomass were studied and functional groups involved in the binding of Cu(II), Mn(II), Zn(II) ions were determined (mainly carboxylic and hydroxylic groups). An interesting and unique element of this work is the verification of the properties of prepared feed additives in conditions simulating the digestive tract of animals. The release of components in solutions simulating conditions in the intestine and stomach (pH 11 and pH 1) was tested (in vitro tests). The best desorption results were achieved at a strongly acidic pH which corresponds to the stomach environment: 9.80, 14.4% Cu(II), 69.0, 66.9% (Zn), 46.5, 31.9 Mn(II) for alfalfa and goldenrod, respectively. It was concluded that the biomass enriched with micronutrients in biosorption has the potential as a feed additive for sustainable agriculture.

Selenium and Nano-Selenium Biofortification for Human Health: Opportunities and Challenges

Selenium is an essential micronutrient required for the health of humans and lower plants, but its importance for higher plants is still being investigated. The biological functions of Se related to human health revolve around its presence in 25 known selenoproteins (e.g., selenocysteine or the 21st amino acid). Humans may receive their required Se through plant uptake of soil Se, foods enriched in Se, or Se dietary supplements. Selenium nanoparticles (Se-NPs) have been applied to biofortified foods and feeds. Due to low toxicity and high efficiency, Se-NPs are used in applications such as cancer therapy and nano-medicines. Selenium and nano-selenium may be able to support and enhance the productivity of cultivated plants and animals under stressful conditions because they are antimicrobial and anti-carcinogenic agents, with antioxidant capacity and immune-modulatory efficacy. Thus, nano-selenium could be inserted in the feeds of fish and livestock to improvise stress resilience and productivity. This review offers new insights in Se and Se-NPs biofortification for edible plants and farm animals under stressful environments. Further, extensive research on Se-NPs is required to identify possible adverse effects on humans and their cytotoxicity.

The Effect of Dietary Humic Preparations on the Content of Essential and Non-Essential Chemical Elements in Hen Eggs

This study was conducted to determine the effect of dietary supplementation with two humic preparations, Humokarbowit (HKW) and Humobentofet (HBF), on the mineral content of the albumen and egg yolk of Lohmann Brown hens. The content of macroelements (Ca, K, Mg, Na, P, S), microelements (Al, Ba, Cu, Fe, I, Mn, Si, Sr, Zn) and trace elements (Ag, As, Be, Bi, Cd, Co, Cr, Ga, Hg, Li, Mo, Ni, Pb, Rb, Sb, Se, Sn, Ti, Tl, V, W, Y and Zr) in the feed mixture (FM), albumen and yolk were presented. The material was collected from laying hens kept in a cage system in two groups, control (C) and enriched (E), with standard feed and feed enriched with humic preparations, respectively. The enriched feed mixture was characterised by a significantly higher Ag, Ba, Be, Bi, Co, Fe, Ga, Hg, K, Mg, Ni, S, Sb, Si, Zn and Zr content compared to the standard, basal mixture. Only some of these elements were found in significantly increased levels in albumen (Bi, Co, Ni, S) and yolk (Bi, Fe, K, Sb). Another noteworthy finding was a significantly lower concentration of Na in the content of eggs from the E-Group, which corresponds to the content of this important macronutrient in the feed. In addition, a significant increase in the concentration of elements such as Al, I, Li, Sr, Ti, Tl, Y, W was noted with a reduction in Cd, Cr, Hg, Mn, Rb, Sn in Group-E, which indicates a complicated egg formation processes, including biotransfer-essential and non-essential chemical elements.