Meta-analysis of Zinc Supplementation on Laying Performance, Egg Quality Characteristics, and Blood Zinc Concentrations in Laying Hens

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.

A meta-analysis of essential oils as a dietary additive for weaned piglets: Growth performance, antioxidant status, immune response, and intestinal morphology

This study aimed to evaluate the effects of dietary supplementation with EOS on growth performance, blood serum antioxidant status, immune response, and intestinal morphology of weaned piglets using a meta-analytical approach. The database included 31 studies from which the response variables of interest were obtained. All data were analyzed using a random effects model, and results were expressed as weighted mean differences between treatments supplemented with and without EOS. EOS supplementation increased (P < 0.001) average daily feed intake, average daily gain, and final body weight and decreased (P < 0.001) feed conversion ratio and diarrhea incidence. Lower (P = 0.001) serum malondialdehyde content and higher (P < 0.05) serum concentrations of superoxide dismutase, catalase, glutathione peroxidase, and total antioxidant capacity were observed in response to the dietary inclusion of EOS. EOS supplementation increased (P < 0.001) the serum concentration of immunoglobulins A, G, and M and decreased (P < 0.05) the serum concentration of tumor necrosis factor-α, interleukin-1β, and interleukin-6. Greater (P ≤ 0.001) villus height (VH) was observed in the jejunum and ileum in response to the dietary inclusion of EOS. However, EOS supplementation did not affect (P > 0.05) crypt depth (CD) and decreased (P < 0.001) the VH/CD ratio in the duodenum, jejunum, and ileum. In conclusion, essential oils can be used as a dietary additive to improve growth performance and reduce the incidence of diarrhea in weaned piglets and, at the same time, improve the antioxidant status in blood serum, immune response, and intestinal morphology.

Trace Minerals in Laying Hen Diets and Their Effects on Egg Quality

With the advancement in the egg industry sector, egg quality has assumed great significance in certain countries. Enhancements in the nutritional value of eggs may have direct affirmative consequences for daily nutrient intake and therefore for human health. Thus, affirmative improvement in egg quality boosts consumer preferences for eggs. Also, the improvement in eggshell quality can avoid the disposal of broken eggs and consequently economic losses. Therefore, poultry nutrition and mineral supplements have a significant impact on egg quality. Minerals are crucial in poultry feed for a number of biological processes, including catalytic, physiologic, and structural processes. For instance, they contribute to the biological processes necessary for forming and developing eggshells. To produce high-quality eggs for sale, diets must therefore contain the right amount of minerals. This review aims to highlight the role of both organic and inorganic minerals in improving egg quality, in addition to reviewing the interactions of mineral supplements with intestinal microbiota and subsequent effects on the egg quality.

A Meta-analysis of Responses of Broiler Chickens to Dietary Zinc Supplementation: Feed Intake, Feed Conversion Ratio and Average Daily Gain

The importance of zinc (Zn) in broiler chicken nutrition is gaining attention due to the realization of its role in several enzymes and metabolic functions. This meta-analysis, therefore, aimed to synthesize pooled evidence on the effectiveness of Zn supplementation on enhancing feed intake, feed conversion ratio (FCR) and average daily gain (ADG) in broiler chickens. Thirty-seven peer-reviewed studies out of 436 identified from the search carried out in Scopus, Google Scholar and PubMed databases met the criteria for inclusion in this meta-analysis. Data were pooled and then disaggregated for moderators: broiler strains, sources of Zn, duration of Zn supplementation and Zn supplementation levels. All the analyses were conducted in Open Meta-analyst for Ecology and Evolution (OpenMEE) software. Pooled results indicate that Zn supplementation increased feed intake [standardised mean differences (SMD) = 0.34 g/bird/day; 95% confidence interval (CI) 0.27, 0.42)] and ADG (SMD = 0.43 g/bird/day; 95% CI 0.35, 0.50) in broiler chickens in comparison with the controls. Dietary Zn supplementation improves FCR (SMD =  - 0.16 g/g; 95% CI 0.20, - 0.11), taking heterogeneity and publication biases into account. Restricted subanalysis showed that studied moderators influenced the outcomes of the meta-analysis. Meta-regression revealed that moderators explain about 38% of the sources of variations in the present study. This meta-analysis suggests that dietary zinc supplementation had a positive effect on growth performance indices in broiler chickens.

Potentials of Dietary Zinc Supplementation in Improving Growth Performance, Health Status, and Meat Quality of Broiler Chickens

The demand for chicken meat is on the rise, necessitating high level of production and efficient feed conversion which to a certain extent can be actualized by the use of specific trace minerals like zinc (Zn). Zn is a part of several enzymes involved in the metabolism of protein, fat, carbohydrates, and nucleic acids. In addition, Zn has antioxidant properties and is vital for hormone function, including growth, pancreatic, and sex hormones. Its deficiency in animals is characterized by poor fertility, decreased feed intake, poor growth, testicular atrophy, and weakened immunity. Nano-Zn sources have been shown to be more bioavailable than conventional zinc (organic and inorganic) sources. Zn from organic sources, on the other hand, has higher bioavailability than Zn from inorganic sources. Furthermore, Zn supplementation promotes growth, enhances antioxidant capacity, modulates the immunity, and improves health indices in broiler chickens. Published studies have demonstrated that Zn supplementation has the potential to improve carcass yield and meat quality in broilers with various research contradictions. However, a clear understanding of the role of Zn in broiler nutrition is still lacking, necessitating further research. As a result, the purpose of this review was to highlight the influence of Zn (organic or inorganic) supplementation on growth, blood characteristics, antioxidant status, immune responses, Zn tissue/fecal concentrations, intestinal villus histomorphology, and meat quality of broiler chickens as well as Zn bioavailability to understand the role of Zn in broiler nutrition, resolve contradictory research results, and identify knowledge gaps. Understanding the role of dietary Zn in broiler chicken nutrition and meat quality will avail important suggestion on policy advancements and sustainable use of Zn in the broiler chicken industry.

Maternal supplementation of different trace mineral sources on broiler breeder production and progeny growth and gut health

Trace mineral minerals Zn, Cu, and Mn play important roles in breeder production and progeny performance. The objective of this study was to determine maternal supplementation of trace mineral minerals on breeder production and progeny growth and development. A total of 540 broiler breeders, Cobb 500 (Slow feathering; 0–66 weeks old) were assigned to one of three treatment groups with the same basal diet and three different supplemental trace minerals: ITM–inorganic trace minerals in sulfates: 100, 16, and 100 ppm of Zn, Cu, and Mn respectively; MMHAC -mineral methionine hydroxy analog chelate: 50, 8, and 50 ppm of bis-chelated MINTREX®Zn, Cu and Mn (Novus International, Inc.), and TMAAC - trace minerals amino acid complex: 50, 8, and 50 ppm of Zn, Cu, and Mn. At 28 weeks of age, eggs from breeder treatments were hatched for progeny trial, 10 pens with 6 males and 6 female birds per pen were fed a common diet with ITM for 45 days. Breeder production, egg quality, progeny growth performance, mRNA expression of gut health associated genes in breeder and progeny chicks were measured. Data were analyzed by one-way ANOVA; means were separated by Fisher’s protected LSD test. A p-Value ≤ 0.05 was considered statistically different and 0.1 was considered numerical trend. Breeders on ITM treatment had higher (p &lt; 0.05) body weight (BW), weight gain and lower (p &lt; 0.05) feed conversion ratio (FCR) from 0 to 10 weeks, when compared to birds fed MMHAC. MMHAC significantly improved egg mass by 3 g (p &lt; 0.05) and FCR by 34 points (0.05 &lt; p &lt; 0.1) throughout the reproductive period (26–66 weeks) in comparison to ITM. MMHAC improved (p &lt; 0.01) egg yolk color versus (vs.) ITM and TMAAC in all periods, except 28 weeks, increased (p &lt; 0.01) eggshell thickness and resistance vs. TMAAC at 58 weeks, and reduced (p &lt; 0.05) jejunal NF-κB gene expression vs. TMAAC at 24 weeks. There was a significant reduction in tibial dry matter weight, Seedor index and resistance for the breeders that received MMHAC and/or TMAAC when compared to ITM at 18 weeks. Lower seedor index but numerically wider tibial circumference was seen in hens fed MMHAC at 24 weeks, and wider tibial circumference but lower tibial resistance in hens fed TMAAC at 66 weeks. Maternal supplementation of MMHAC in breeder hens increased (p &lt; 0.0001) BW vs. ITM and TMAAC at hatching, reduced (p &lt; 0.05) feed intake vs. ITM at d14 and d28, and improved (p &lt; 0.01) FCR and performance index vs. TMAAC at d28, reduced (p &lt; 0.01) NF-κB gene expression and increased (p &lt; 0.05) A20 gene expression vs. TMAAC on d0 and vs. ITM on d14, reduced (p &lt; 0.05) TLR2 gene expression vs. ITM on d0 and vs. TMAAC on d14, increased (p &lt; 0.05) MUC2 gene expression vs. both ITM and TMAAC on d45 in progeny jejunum. Overall, these results suggest that supplementation with lower levels of MHA-chelated trace minerals improved breeder production and egg quality and reduced breeder jejunal inflammation while maintaining tibial development in comparison to those receiving higher inorganic mineral supplementation, and it also carried over the benefits to progeny with better growth performance, less jejunal inflammation and better innate immune response and gut barrier function in comparison to ITM and/or TMAAC.

Zinc supplementation improves antioxidant status, and organic zinc is more efficient than inorganic zinc in improving the bone strength of aged laying hens

Background

There have been some reports indicating that supplementation of zinc could alleviate the negative effects of age on egg quality in laying hens. However, information regarding these positive effects on health and zinc deposition in the body is limited.

Objectives

The aim of the present study was to investigate the effect of organic and inorganic sources of zinc on the antioxidant activity, bone strength, and zinc deposition in the tissues of older laying hens.

Methods

In a completely randomized design, 175 Leghorn laying hens (w36) aged 80 weeks were allocated into seven treatment groups and five replications: control (without zinc supplementation), zinc sulphate treatments (15, 30, and 45 mg/kg), and organic zinc treatments (15, 30, and 45 mg/kg).

Results

There was a significant increase in feed intake in the zinc sulphate and organic zinc treatments compared to the control treatment (p < 0.05). The egg mass in organic and sulphate zinc showed a significant increase. The feed conversion ratio was decreased significantly in the organic zinc treatments (p < 0.05). Both organic and sulphate zinc supplements enhanced serum superoxide dismutase activity as an antioxidant index (p < 0.05). The cortical thickness of the tibia was improved in laying hens receiving 30 mg/kg organic zinc. Supplementation of zinc could lead to an increase in zinc deposition in tissues, and organic zinc boosts bone strength.

Conclusion

Zinc supplementation can improve antioxidant activity, feed intake, and feed conversion ratio and enhance egg mass and optimal absorption of zinc in tissues. The use of 30 mg/kg organic zinc is recommended for improving the cortical thickness of the tibia in aged laying hens.