Dietary Zn Levels Research Articles

Adequate Levels of Zinc and Copper on Turkey Poult Performance, Immunological Response, and Skeletal Health.

In this study, the impact of varying dietary zinc (Zn) and copper (Cu) levels on the growth, immunological response, and skeletal health of developing turkey poults was investigated. For 0-4 and 5-8 weeks of age, respectively, three Zn levels of 50, 70, and 90mg/kg and 45, 65, and 85mg/kg were employed. Three Cu levels, namely 8, 12, and 16mg/kg for 0-8 weeks of age, were also utilized. There were 288 (9 × 4 × 8) day-old turkey poults with equal body weight that were randomly assigned to 9 treatments, each consisting of 4 replicates and 8 poults per replicate. In comparison to other dietary combinations, there was a significant (P ≤ 0.05) increase in body weight gain observed in the 90 and 85mg Zn/kg with 16mg Cu/kg diet during 0-4 and 0-8 weeks of age, respectively, and the 70 and 65mg Zn with 16mg Cu /kg diet during 0-4 and 0-8 weeks of age, respectively. When compared to low levels of zinc in the diet at 5-8 and 0-8 weeks of age, respectively, feed conversion ratio was shown to be significantly (P ≤ 0.01) better with 90 and 85mg Zn/kg diet. In a similar pattern, feed utilization efficiency was considerably (P ≤ 0.01) higher at 16mg Cu/kg diet than it was at lower Cu levels in the diets given to the animals over the 0-4 week period. Compared to other dietary combinations, there was a substantial (P ≤ 0.01) improvement in cell-mediated immune response (foot web index to PHAP) and humoral immune response (HA titer to SRBC) when 85mg zinc and 16mg copper/kg diet was consumed at 0-4 and 5-8 weeks of age. At greater dietary Zn and Cu levels than its lower values, the weight of the spleen and thymus was considerably (P ≤ 0.05) higher. In a dietary combination of 90mg Zn with 16mg Cu/kg during 0-4 and 85mg Zn with 16mg Cu/kg diet during 5-8 weeks of age, respectively, there were significantly (P ≤ 0.05) greater bone width (proximal and distal), tibia bone ash, calcium, and phosphorus detected respectively. Significantly (P ≤ 0.01) greater Zn and Fe contents were found in the tibia bone at 90 and 85mg Zn/kg diet, respectively, compared to values obtained at other Zn levels in the diet throughout 0-4 and 5-8 weeks of age. During the first 8 weeks of life, a diet containing 12mg of copper per kilogram was shown to have a significantly (P ≤ 0.05) increased Zn and Fe content in the tibia bone compared to other levels. It is possible to draw the conclusion from the data that, for growing turkey poults, dietary combinations of 90mg Zn/kg with 16mg Cu/kg diet and 85mg Zn with 16mg Cu/kg diet between 0 and 4 and 5-8 weeks of age, respectively, were sufficient for optimum development, immunity, and skeletal health indices.

Dietary zinc requirement of juvenile stinging catfish Heteropneustes fossilis based on growth performance, haematology, and tissue mineral composition

This investigation was done to determine how much zinc (Zn) the stinging catfish, Heteropneustes fossilis, needs in its diet. Five isonitrogenous (34.5% protein) and isolipidic (6.0% lipid) diets were prepared to contain graded levels of Zn (0, 10, 20, 30, and 40 mg kg−1), supplied as zinc sulfate (ZnSO4·7H2O), and referred to as Zn0, Zn10, Zn20, Zn30, and Zn40, respectively. A total of 600 fish (initial body weight: 1.41 ± 0.02 g) were stocked in 15 glass aquaria (40 fish/aquarium), each with 180 L water capacity. For ten weeks, each diet was hand fed to three groups of fish twice daily until they appeared satisfied. The highest weight gain and specific growth rate, and lowest feed conversion ratio were recorded in fish fed with a 30 mg Zn kg−1 diet. Zn contents in bone and muscle linearly increased up to 30 mg kg−1 Zn and then remained stable, while iron (Fe) and copper (Cu) contents in bone and muscle had an inverse pattern with the inclusion level of dietary Zn. Increasing dietary Zn levels up to 30 mg kg−1 was found to improve values of hematological parameters such as red blood cell (RBC), white blood cell (WBC), haemoglobin (Hb), and haematocrit (HCT). These values, however, decreased when the dietary Zn level was further increased. The serum alkaline phosphatase level was the highest in fish fed a diet containing 30 mg kg-1 of Zn. Regression analyses based on weight gain, specific growth rate, and bone and muscle Zn concentrations indicated that the optimum dietary Zn requirement for stinging catfish was in a range of 27.4–36.5 mg kg−1.

Zinc status and indicators of intestinal health in enterotoxigenic Escherichia coli F18 challenged newly weaned pigs fed diets with different levels of zinc.

This study investigated the impact of an enterotoxigenic Escherichia coli (ETEC) F18 challenge on newly weaned pigs when fed one of three Zn levels (150, 1,400, or 2,500ppm) on performance, Zn status, ETEC shedding, and diarrhea. The ETEC challenge was hypothesized to have a more pronounced negative impact on pigs fed a diet containing 150ppm Zn compared to 1,400 or 2,500ppm Zn for 14 d after weaning. The study included 72 ETEC F18 susceptible pigs weaned at ~28 d of age (d 0 of the study). The pigs were distributed according to initial weight and litter to one of the three dietary Zn levels. Half of the pigs were challenged with ETEC on d 1 and 2. The challenge reduced (P ≤ 0.03) feed intake and average daily gain (ADG) during d 3 to 5. Challenged pigs fed 150ppm Zn had lower (P = 0.01) ADG during d 5 to 7 compared to those fed 1,400 or 2,500ppm Zn, whereas control pigs' ADG were not affected by dietary Zn content. Challenged pigs fed 150ppm Zn also showed lower (P < 0.01) fecal dry matter (DM) on d 5 compared to control pigs fed 150ppm Zn and challenged pigs fed 1,400 or 2,500ppm Zn. Challenge increased (P < 0.01) ETEC shedding in all groups, but challenged pigs fed 150ppm Zn showed higher (P ≤ 0.05) fecal shedding of ETEC and toxins than when fed 1,400 or 2,500ppm. On d 3, C-reactive protein concentration in plasma was lower (P < 0.03) for pigs fed 1,400 and 2,500 compared to 150ppm Zn. Plasma haptoglobin and pig major acute phase protein were unaffected by dietary Zn content. On d 0, the serum Zn concentration was 586 ± 36.6 µg/L, which pigs fed 150ppm Zn maintained throughout the study. The serum Zn concentration increased (P ≤ 0.07) in pigs fed 1,400 or 2,500ppm Zn. The challenge decreased (P < 0.01) the serum Zn concentration in pigs fed 2,500ppm Zn. On d 5 and 7, serum Zn concentration was similar for challenged pigs fed 1,400 and 2,500ppm Zn, while control pigs fed 2,500ppm Zn had higher (P < 0.01) serum Zn concentration than 1,400ppm Zn. On d 7, serum Zn concentration tended (P = 0.08) to be lower for pigs with diarrhea (fecal DM ≤ 18%). In summary, these results indicate that newly weaned pigs fed 150ppm Zn are more susceptible to ETEC F18 colonization and its adverse consequences such as diarrhea and reduced growth, even though challenge did not increase acute phase proteins.

L-shaped association between dietary zinc intake and cognitive decline in Chinese older people.

The prospective association between dietary zinc (Zn) intake and cognitive decline remains uncertain. We aimed to assess the relationship of dietary Zn intake with the risk of cognitive decline in the Chinese older people, and examine the possible effect modifiers on this association. A total of 3,106 older Chinese adults aged 55years or older from China Health and Nutrition Survey were included. Dietary nutrients intake information was collected by combined 24-h dietary recalls with weighing food inventory. The cognitive decline was defined as the 5-year decline rate in global and composite cognitive scores, based on a subset of items from the Telephone Interview for Cognitive Status-modified. The median follow-up duration was 5.9years. There was an L-shaped association between dietary Zn intake and the 5-year decline rates in global and composite cognitive scores, with an inflection point at 8.8mg/day of dietary Zn. For the composite cognitive scores, compared with the first quantile (<7.9mg/day) of dietary Zn intake, quantiles 2-6 (≥7.9mg/day) had a significantly slower cognitive decline rate (β: -0.24; 95% confidence interval: -0.40 to -0.07). Similar results were found for the global cognitive scores. Moreover, the inverse association between dietary Zn intake and cognitive decline in composite cognitive scores was significantly stronger in those with lower levels of physical activity (P-interactions = 0.041). Dietary Zn intake was negatively associated with cognitive decline in the older people. Maintaining appropriate dietary Zn levels may prevent cognitive decline.

Zinc dampens antitumor immunity by promoting Foxp3+ regulatory T cells.

The role of zinc (Zn) in tumor development and immune modulation has always been paradoxical. This study redefines our understanding of the impact of Zn on cancer progression and therapeutic strategies. We investigated the effects of dietary Zn levels on tumor progression and immune responses. This included examining the impact of both high and deficient dietary Zn, as well as Zn chelation, on tumor growth and immune cell populations. Specifically, we analyzed the frequency of Foxp3+ regulatory T-cells (Tregs) and identified the role of FOXO1 in Zn-mediated effects on Tregs. Additionally, we explored the therapeutic potential of clioquinol (CQ) in enhancing α-PD-1 immunotherapy responses, particularly in melanoma. Our findings show that high dietary Zn promotes tumor progression by fostering a protumorigenic environment mediated by T cells. Increased Zn intake was found to facilitate tumor progression by increasing Foxp3+ Treg frequency. In contrast, deficiency in dietary Zn and chelation of tissue Zn emerged as potent drivers of antitumor immunity. We pinpointed FOXO1 as the master regulator governing the influence of Zn on Tregs. These results reveal a novel mechanistic insight into how Zn influences tumor progression and immune regulation. The identification of FOXO1 as a key regulator opens new avenues for understanding the role of Zn in cancer biology. Furthermore, we introduce a promising therapeutic approach by showing that administering clioquinol (CQ) significantly enhances α-PD-1 immunotherapy response, particularly in melanoma. These revelations transform our comprehension of the multifaceted role of Zn in tumorigenesis and immune regulation, highlighting innovative possibilities for cancer therapy.

Estimation of digestible zinc and copper in pigs: a meta-analysis approach

The objective of this study was to quantify the impact of Zn and Cu supplementation and nutritional factors on the digestible content of these minerals using a meta-analysis approach. A database derived from 24 publications and describing 142 experimental treatments was compiled. A model showed that positive effects of chelated, (linear and quadratic, P &lt; 0.01) and inorganic Zn supplementation ( P &lt; 0.05) (linear and quadratic, P &lt; 0.01), Zn from ingredients (linear, P &lt; 0.01) and a negative linear effect of dietary Cu concentration ( P = 0.067; R2= 94%) on digestible Zn content. In other model, addition of phytase showed linear improvement of digestible Zn ( P &lt; 0.01; R2= 96%). For digestible Cu, a model showed that chelated and inorganic Cu supplementation ( P &lt; 0.01) linearly increased digestible Cu while dietary Zn level decreased it ( P &lt; 0.01; R2 = 93%). Dietary phytase did not impact digestible content of Cu. The digestibility of Zn and Cu depends on dietary supplementation of these minerals in diets but also on the interaction between these minerals. Finally, phytase supplementation improves digestible Zn content but not Cu.

Optimal dietary zinc inclusion improved growth performance, serum antioxidant capacity, immune status, and liver lipid and glucose metabolism of largemouth bass (Micropterus salmoides)

This study was conducted to ascertain the effect of dietary Zn on growth and health status of juvenile largemouth bass (Micropterus salmoides). Six experimental diets with Zn level of 50.17, 56.74, 73.34, 86.03, 123.94, and 209.20 mg/kg, respectively were compounded using complex amino acid-chelated zinc, and were fed to juvenile fish (5.50 ± 0.10 g) for 70 d. The specific growth rate (SGR) varied with dietary Zn level in a quadratic model and peaked at the 73.34 mg/kg group, while the feeding rate exhibited an opposite trend (P < 0.05). The condition factor, hepatosomatic index and mesenteric fat index all exhibited a tendency similar with SGR (P < 0.05). Dietary Zn level affected serum total proteins, urea, triglycerides, and glucose (P < 0.05). Serum Zn and copper levels linearly increased with dietary Zn level, while serum iron and manganese showed the opposite trend. Serum superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) increased with dietary Zn level and reached a plateau at 86.03 mg/kg. Serum complement component 3 (C3), IgM, and lysozyme also were enhanced by 73.34 mg/kg Zn. Body protein content increased with zinc level up to 73.34 mg/kg, and then remained steadily. As dietary Zn level increased, hepatic lipid level increased and then reached a plateau at 86.03 mg/kg group, while glycogen increased linearly. Moreover, gene expression related to lipid and glycogen metabolism from liver transcriptome further explained the liver lipid and glycogen variations. To conclude, a dietary Zn requirement of 76.99 mg/kg was suggested for juvenile largemouth bass to improve growth, antioxidant capacity, and immune status.

Dietary zinc levels affect growth, appetite, and lipid metabolism of Chinese perch (Siniperca chuatsi).

An 84-day feeding experiment was conducted to investigate the effects of dietary Zn (zinc) on growth performance, food intake, and lipid metabolism of Chinese perch (Siniperca chuatsi). Five isonitrogenous and isolipidic diets with differential Zn contents (67, 100, 149, 230, and 410mg/kg) were fed to 270 fish (35.47 ± 0.49g). Results showed that fish growth and food intake increased markedly with the dietary 149mg/kg Zn levels. Meanwhile, the food intake of 149mg/kg group was significantly higher than that of other treatment groups after feeding for 8weeks (P < 0.05). The qRT-PCR results showed that the expression of center appetite regulation factors in the hypothalamus was significantly regulated, and 149mg/kg significantly increased mRNA expression of npy (neuropeptide Y) and decreased pomc (anorexigenic proopiomelanocortin) and cart (cocaine- and amphetamine-regulated transcript) gene expression. Meanwhile, the expressions of the main genes (such as leptin A and ghrelin) involved in peripheral appetite regulation factors were significantly up-regulated firstly and then reduced with the dietary Zn level increased, whereas the expression of cck (cholecystokinin) was significantly up-regulated. Serum AST (aspartate transaminase) and ALT (alanine transaminase) activities in fish fed the diets containing 230 and 410mg/kg were significantly higher than that in other groups (P < 0.05). The lipid content of liver in 67 and 100mg/kg groups was significantly higher than other groups (P < 0.05). Furthermore, dietary Zn significantly elevated the serum TG (triglyceride) and TCHO (total cholesterol) content levels (P < 0.05). Fish fed a high Zn diet (149, 230, and 410mg/kg) dramatically down-regulated expression of srebp1 (sterol regulatory element binding proteins1c) and fas (fatty acid synthetase), but up-regulated expression of pparα (peroxisome proliferators-activated receptor-α) and cpt1 (carnitine palmitoyl transferase I) in the liver. The optimal dietary Zn inclusion level ranged from 146.69 to 152.86mg/kg diet, based on two-slope broken-line regression analysis of WGR (weight gain rate) and FCR (feed conversion rate) for Chinese perch.

Effects of dietary zinc levels on growth, intestinal health, antioxidant and non-specific immunity of spotted seabass (Lateolabrax maculatus) reared at two temperatures

This study investigated effects of dietary zinc levels and water temperature on growth, feed utilization, intestinal health, antioxidant and non-specific immunity of spotted seabass. Six experimental diets were formulated to contain 30, 53, 77, 98, 116, or 145 mg Zn/kg. Each diet was fed to two different groups of fish reared at low temperature (27 °C; LT) or high temperature (33 °C; HT). Triplicate groups of fish were fed the test diets to apparent satiation two times daily for 8 weeks. Results showed that fish under HT showed the lower weight gain (WG) and higher feed conversion rate (FCR) comparing to the LT treatment (P < 0.05). Also, the growth and feed utilization were significantly (P < 0.05) influenced by dietary Zn levels and broken-line regression analysis showed the optimal dietary Zn level for spotted seabass reared at 27 °C and 33 °C are 77.69 mg/kg and 93.61 mg/kg, respectively. Apparent digestibility coefficients (ADCs) of protein and lipid in HT treatment were significantly lower than those of LT treatment (P < 0.05), and ADCs significantly increased with the increase of dietary Zn levels. The histology showed HT and Zn-deficiency can cause the damage of intestine, while fish fed 77 mg Zn/kg diets presented normal structure. Serum LZM activity, C3 and IgM contents of HT treatments were lower than those of the LT treatments. Further, LZM activity, C3, and IgM contents can be significantly elevated by the increasing of dietary Zn levels. MDA content of HT treatments were significantly higher than that of LT treatments, while MDA content decreased with the increase of dietary Zn levels as SOD activity and T-AOC increased. Overall, the optimum dietary Zn level alleviated heat stress via enhancing immunity, antioxidant capacity and intestine health.

Effects of dietary zinc (Zn) levels on growth performance, nutrient composition, muscle development, antioxidant and inflammatory responses in yellow catfish muscle

Three diets were formulated with dietary zinc (Zn) levels at 12.10 mg Zn/kg (L-Zn), 18.69 mg Zn/kg (M-Zn) and 120.82 mg Zn/kg (H-Zn) to explore effects of dietary Zn on growth, nutrient composition, muscle development, antioxidant and inflammatory responses in the muscle tissues of yellow catfish, one of the important economic fish in several Asian countries, including China. Zn content in M-Zn group could meet Zn requirement of yellow catfish. 270 juvenile yellow catfish (4.97 ± 0.01 g, mean ± S.E.M) were stocked in nine 300-L indoors tanks, 30 yellow catfish in each tank, and randomly provided with three diets for 10 weeks. Among three treatments, yellow catfish fed the middle Zn diets showed higher growth performance and condition factor but lower feed conversion rate than those fed the high Zn diets. Dietary Zn addition increased muscle Zn contents, but did not significantly influence feed intake, viscerosomatic and hepatosomatic index, survival, moisture, lipid, crude protein and ash contents in the muscle. Dietary Zn levels significantly influenced mRNA expression of several muscle development-related genes, such as mef2a, myod, myf5, myog, mef2d, pax7, mrf4, myhc and mstn. Middle dietary Zn levels increased antioxidant capability and reduced oxidative stress, as evaluated by enzymatic activities, gene and protein expression related to antioxidant response. Fish fed the middle Zn diets had the lower il8, tnf-α and tnf-β mRNA expression but higher il10 and tgf-β mRNA expression than those fed the high Zn diet, suggesting that optimal dietary Zn levels activated anti-inflammatory response and inhibited pro-inflammatory responses. Based on the observation, our study suggested that the suitable dietary Zn levels promoted the growth, muscle development, antioxidant and anti-inflammatory responses in fish.

Integrated evaluation of the requirements and excretions of Cu, Fe, Zn, and Mn for broilers via a uniform design method.

This study aimed to determine the ideal balance profile of Cu, Fe, Zn, and Mn for broilers of 1-21 days of age via a uniform experimental design. In Experiment 1, 900 1-day-old Arbor Acres male broilers were randomly allotted to 15 dietary treatments with six replicates of 10 birds. A total of 14 experimental diets were formulated with the supplementation of 8~16, 123~160, 40~80, and 60~120 mg/kg of Cu, Fe, Zn, and Mn, respectively, in the basal diet, according to the uniform design method. The excretion of Cu, Fe, Zn, and Mn in the manure and the broiler performance were determined to build the ideal balance profile of these elements. Experiment 2 was conducted based on the ideal balance profile built in Experiment 1, to test its practicability using 720 broilers with two treatments. The dietary concentrations of Cu, Fe, Zn, and Mn in the control group were 15.19, 203.08, 76.78, and 86.13 mg/kg, respectively. In Experiment 1, the concentrations of Cu, Fe, Zn, and Mn in the diets were 16.96, 166.66, 46.01, and 60.26 mg/kg, respectively, when the average daily gain reached the optimum value. When the dietary concentrations of Cu, Fe, Zn, and Mn were 8.54, 130.66, 38.19, and 64.07 mg/kg, respectively, the total excretion of Cu, Fe, Zn, and Mn got the minimum value. There are corresponding ideal balance profiles for minimum excretion of a certain element. In Experiment 2, the dietary levels of Fe, Zn, and Mn were decreased by 17.93%, 40.08%, and 30.04%, respectively, which had no significant effect on average daily gain, average daily feed intake, and feed gain for 1~21 day-old broilers but markedly decreased the excretion of Cu and Mn and total excretion. It was concluded that there is a dilemma between growth performance and mineral excretion. Although dietary levels of Cu, Fe, Zn, and Mn supporting optimal growth are higher than those for minimizing mineral excretion, supplementing too many trace elements in the diets of broilers is unnecessary.

Effects of dietary zinc/copper ratios on the metabolism of zinc and copper in weaned pigs.

This study compared the effects of different dietary zinc/copper ratios on zinc (Zn) and copper (Cu) metabolism in weaned pigs. One hundred and sixty piglets (7.81 ± 0.25 kg; 21 d of age) were used in a completely randomized 2 × 2 factorial design composed with high (H) and low (L) levels of added dietary Zn (100 and 3,000 mg/kg) and dietary Cu (6 and 130 mg/kg). Piglets were slaughtered at 21, 28, 35, and 42 d of age for blood and tissues collection. Serum, jejunum mucosa, liver, and kidney concentrations of Zn and Cu were analyzed as well as tissues mRNA abundance of genes related to their metabolism. Serum and liver Zn concentrations increased at days 28, 35, and 42 in HZn groups compared to pre-treatment levels (day 21; P ≤ 0.01) but for LZn animals, values decreased at days 28, 35, and 42 in liver (P ≤ 0.01) but remained stable vs. day 21 levels in serum (P ≥ 0.37). Serum, jejunum mucosa, liver, and kidney Zn concentrations were greater in HZn groups from day 28 (P ≤ 0.01). In jejunum mucosa, the mRNA expression of ZIP4 was lower in HZn piglets at day 28 (P ≤ 0.01) and at day 42 whereas HCu supplementation increased ZIP4 expression in LZn but not in HZn diets (P = 0.05). For ZNT1, MT3, and MT1, values of relative mRNA expression were greater for HZn animals in jejunum mucosa, liver, and kidney (P ≤ 0.01) from day 28. In kidney (P < 0.01) at day 42, HZn supplementation increased MTs expression in both LCu or HCu groups. Serum and liver Cu concentrations decreased at days 35 and 42 in all treatments compared to day 21 (P ≤ 0.04), except LZnHCu in liver that was not different from day 21 (P ≥ 0.17). Serum Cu concentrations were lower in HZn and greater in HCu groups at days 35 and 42 (P ≤ 0.01) whereas hepatic Cu was reduced by HZn diets in both LCu and HCu groups at days 35 and 42 (P ≤ 0.01). Jejunum Cu concentrations were increased by HCu diets in HZn but not in LZn groups at days 28 and 42 (P ≤ 0.04). Renal Cu concentrations were greater in HZn groups at day 28 (P < 0.01) whereas at day 42 HZn diets increased Cu values in both LCu and HCu groups (P ≤ 0.01). The expression of ATP7A in kidney at day 42 was greater for HZn groups (P = 0.02). In conclusion, high dietary Zn levels were not efficiently regulated by homeostatic mechanisms and significantly impaired Cu homeostasis. Low dietary Zn/Cu ratios allow a more efficient regulation of the metabolism of these trace minerals in post-weaning piglets. The current official recommendations for Zn and Cu to post-weaning piglets apparently do not fulfill their requirements.

Effects of Phosphorus Supply on Seed Yield and Quality in Flax

Flaxseed, which is rich in lignan, α-linolenic acid, dietary fiber, and several minerals, is an important food and nutrition source. In this study, trials were conducted at Yongdeng over two consecutive years (2018 and 2019), with three cultivars (Longyaza 1, Longya 14, and Zhangya 2) and five application rates of phosphorus (P) (0, 40, 80, 120, and 160 kg P2O5 ha−1). We examined the effects of P on the seed yield, and the yields and contents of dietary fiber, lignan, iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu). We found that P fertilization positively influenced yields of seed and levels of lignan, Fe, and Cu, showing average increases of 15, 20, 24, and 28%, respectively, compared with plants not given P over the 2-year study. Additionally, P fertilization resulted in increased concentrations of Fe and Cu in flaxseed of 8 and 2%, respectively. P fertilization negatively affected the levels of dietary fiber, Zn, and Mn, which were reduced by 7, 11, and 7%, respectively, in comparison with the control. In conclusion, the results demonstrated that appropriate P application is an effective strategy for improving yields of seed, lignan, Fe, and Cu in flax production and for enhancing concentrations of Fe and Cu in flax.

Too Much of a Good Thing: Rethinking Feed Formulation and Feeding Practices for Zinc in Swine Diets to Achieve One Health and Environmental Sustainability.

The objectives of this review were to summarize current knowledge of Zn in swine nutrition, environmental concerns, potential contribution to antimicrobial resistance, and explore the use of alternative feeding strategies to reduce Zn excretion in manure while capturing improvements in productivity. Zinc is a required nutrient for pigs but is commonly supplemented at concentrations that greatly exceed estimated requirements. Feeding pharmacological concentrations of Zn from ZnO to pigs for 1 to 2 weeks post-weaning reduces post-weaning diarrhea and improves growth performance. Feeding elevated dietary levels of Zn to sows during the last 30 days of gestation can reduce the incidence of low-birth-weight pigs and pre-weaning mortality. Most of the dietary Zn consumed by pigs is not retained in the body and is subsequently excreted in manure, which led several countries to impose regulations restricting dietary Zn concentrations to reduce environmental impacts. Although restricting Zn supplementation in swine diets is a reasonable approach for reducing environmental pollution, it does not allow capturing health and productivity benefits from strategic use of elevated dietary Zn concentrations. Therefore, we propose feeding strategies that allow strategic use of high dietary concentrations of Zn while also reducing Zn excretion in manure compared with current feeding practices.

250 Effect of Dietary Zinc and Copper Supplements on Digestibility of Minerals in Growing Pigs

Abstract Dietary zinc (Zn) and copper (Cu) supplementation can affect the digestion and absorption of nutrients in pigs, especially of minerals. This study aimed to evaluate the effect of dietary levels of Zn and Cu on their ileal (AID) and total tract (ATTD) digestibility and that of manganese (Mn), calcium (Ca), and phosphorus (P). Six crossbred pigs were surgically equipped with a single-T cannula in their distal ileum. In cross over design, pigs received one of a four corn-soybean meal diets supplemented by two levels of Zn (100 and 500 mg/kg as Zn oxide) and two levels of Cu (40 and 80 mg / kg as Cu sulfate) for each period (7d with 2d for ileal digesta and feces collection). In this study, high level of Zn increased Zn and Mn AID (P&amp;lt; 0.01) but decreased Ca AID (P&amp;lt; 0.05). The high level of Cu improved Cu AID but only when high level of Zn was used (Zn x Cu, P&amp;lt; 0.051). The ATTD of Zn, Cu, Mn, and P were greater in pigs receiving 500 mg/kg of Zn (P&amp;lt; 0.01). The high level of Cu also increased its ATTD (P&amp;lt; 0.01) but reduced that of Ca when low level of Zn was added (Zn x Cu, P&amp;lt; 0.01). The post-ileal digestibility showed a significant absorption of Cu, Mn and Ca (digestibility different from 0). The post-ileal digestibility of Cu, Mn and Ca was greater when high level of Zn was added (P&amp;lt; 0.05). This study confirmed that the AID and ATTD of Cu and Zn could be affected by the dietary level of Zn and Cu in growing pigs. This study also showed that high levels of Cu and Zn reduced ATTD and AID of Ca but increased P ATTD. This last result is contradictory and must be confirmed by the analysis of phytic P.

Effects of dietary zinc sources and levels on growth performance, serum biochemical and immunological indexes and tissue zinc content of Litopenaeus vannamei

This investigation aimed at estimating the effects of two zinc (Zn) sources and dietary Zn levels on growth performance, serum biochemical and immune indexes and zinc content of tissues. There were two Zn sources, Zn sulphate heptahydrate (Zn-S) and Zn methionine (Zn-M) with five addition gradients (10, 20, 40, 60, 80 mg/kg), separately, added to the isonitrogenous and isolipidic basal diets. The group without additional Zn supplement served as the control group. In the eight-week experiment, Litopenaeus vannamei (0.34 g initial body weight) was fed 11 kinds of experimental diets respectively (shared control group) for 8 weeks. The results indicated that: 1) dietary Zn-S and Zn-M significantly improved weight gain rate (WGR), specific growth rate (SGR), protein efficiency rate (PER) of shrimp (P < 0.05). Feed conversion ratio (FCR) of both the Zn-S and Zn-M groups was distinctly reduced (P < 0.05). Zn sources and Zn levels and the interaction of them (IZSL) didn't distinctly influence survival rate (SR) of shrimp (P > 0.05). WGR, SGR, PER and FCR were not influenced by Zn sources and IZSL (P > 0.05) while they were significantly influenced by Zn levels (P < 0.05). 2) Contents of body crude protein (CP), crude lipid (CL) and crude ash (CA) were remarkably affected by dietary Zn levels (P < 0.05), and CP content of the body was significantly affected by Zn sources. IZSL had an impact on CA content (P < 0.05). 3) Contents of triglyceride (TG) and cholesterol (CHOL) in serum were significantly increased by dietary Zn-S and Zn-M (P < 0.05), and simultaneously, activities of acid phosphatase (ACP), alkaline phosphatase (AKP) and total superoxide dismutase (SOD) in serum were improved by dietary Zn-S and Zn-M (P < 0.05). There were distinct effects of IZSL on serous activities of ACP and AKP (P < 0.05). 4) Content of Zn in the body and muscle were significantly increased by dietary Zn-S and Zn-M (P < 0.05). Zn content of muscle was significantly affected by Zn sources, but Zn content of body and muscle were not influenced by IZSL (P > 0.05). In conclusion, dietary Zn-M and Zn-S both improved growth performance and immunity of shrimp. Based on WGR and Zn content of the whole body, the optimum requirements of Zn in Zn-S or Zn-M for shrimp were 93.36 ~ 112.28 mg/kg and 66.03 ~ 103.61 mg/kg. Additionally, Zn-M exhibited higher avail and immunity and was recommended in diets of Litopenaeus vannamei.

Determination of the Optimal Level of Dietary Zinc for Newly Weaned Pigs: A Dose-Response Study.

Simple SummaryPiglets have a very low feed intake immediately after weaning. We hypothesise that the EU-legislated maximum dietary zinc concentration (150 mg zinc/kg diet) will increase the risk of zinc deficiency after weaning. Zinc deficiency includes symptoms such as impaired growth and increased risk of diarrhoea. However, a high dietary zinc concentration has an antimicrobial effect on the bacteria and increases the risk of antimicrobial resistance. The findings of this study show that the dietary zinc level had a quadratic effect on growth, with a turning point at an approximately 1400 mg zinc per kg diet. The risk of diarrhoea increased up to 60% for pigs that had a blood zinc concentration which decreased after weaning. Maintaining the blood zinc concentration seven days after weaning required up to 1121 mg zinc per kg diet. There was no evidence for an antimicrobial effect when feeding pigs a diet with up to 1601 mg zinc per kg.One hundred and eighty individually housed piglets with an initial body weight of 7.63 ± 0.98 kg (at 28 days of age) were fed a diet containing either 153, 493, 1022, 1601, 2052 or 2407 mg zinc/kg (added Zn as zinc oxide; ZnO) from day 0–21 post weaning to determine the optimal level of Zn for weaned piglets. Body weight, feed intake and faecal scores were recorded, and blood and faecal samples were collected. Dietary Zn content quadratically affected both feed intake and gain in the first two weeks, with an approximately 1400 mg Zn/kg diet and a Zn intake of 400 mg/day as the optimal levels. The relative risk of diarrhoea increased up to 60% at day 7 and 14 if serum Zn status dropped below the weaning level (767 µg/L), and maintain the weaning serum Zn status required approximately 1100 mg Zn/kg (166 mg Zn/day) during week 1. Blood markers of intestinal integrity (D-lactate and diamine oxidase) were unaffected by dietary Zn, and dietary Zn levels of 1022 and 1601 mg/kg did not affect the faecal numbers of total bacteria, Lactobacilli and E. Coli bacteria compared to 153 mg Zn/kg. These results indicate that the requirement for Zn in newly weaned piglets may be substantially higher than currently assumed.

Dietary Zinc Glycine Supplementation Improves Tibia Quality of Meat Ducks by Modulating the Intestinal Barrier and Bone Resorption.

Leg problems characterized by gait abnormity and bone structure destruction are associated with a high risk of fractures and continuous pain in poultry. Zinc (Zn) acts a pivotal part in normal bone homeostasis and has proven to be highly effective in alleviating leg problems. Therefore, the effects of graded concentration of Zn on bone quality were evaluated in this study. A total of 512 1-d-old male ducks were fed 4 basal diets added 30mg/kg Zn, 60mg/kg Zn, 90mg/kg Zn, and 120mg/kg Zn as Zn glycine for 35 d. Tibia Zn content, ash percentage, and breaking strength linearly increased with dietary elevated Zn level (P < 0.05). Broken-line analysis revealed that the recommended level of Zn from Zn glycine was 55.13mg/kg and 64.48mg/kg based on tibia ash and strength, respectively. To further confirm the role of dietary Zn glycine addition on bone characteristics, data from birds fed either 60mg/kg Zn as Zn sulfate (ZnSO4), 30mg/kg Zn, or 60mg/kg Zn in the form of Zn glycine indicated that birds given 60mg/kg Zn from Zn glycine diet exhibited higher tibia ash, strength, and trabecular volume compared to those fed the 30mg/kg Zn diet (P < 0.05). Dietary 60mg/kg Zn as Zn glycine addition decreased intestinal permeability, upregulated the mRNA expression of tight junction protein, and increased the abundance of Lactobacillus and Bifidobacterium, which was companied by declined the level of inflammatory cytokines in both the ileum and bone marrow. Regarding bone turnover, the diet with 60mg/kg Zn from Zn glycine induced osteoprotegerin expression and thus decreased osteoclast number and serum bone resorption biomarker levels including serum tartrate-resistant acid phosphatase activity and C-terminal cross-linked telopeptide of type I collagen level when compared to 30mg/kg Zn diet (P < 0.05). Except for the upregulation in runt-related transcription factor 2 transcription, the experimental treatments did not apparently change the bone formation biomarker contents in serum. Additionally, Zn glycine displayed a more efficient absorption rate, evidenced by higher serum Zn level, and thus had potentially greater a protective role in the intestine barrier and tibia mass as compared to ZnSO4. Collectively, the dietary supplementation of 60mg/kg in the form of Zn glycine could suppress bone resorption mediated by osteoclast and consequently improve tibial quality of meat ducks, in which enhanced intestinal integrity and optimized gut microbiota might be involved.

Zinc supplementation in practical diets for pond-raised hybrid snakehead (Channa maculate ♀ × Channa argus ♂) fingerlings: Effects on performance, mineral retention and health

Zinc (Zn) is an essential micromineral for fishes and is closely related to many biochemical processes. This study was designed to determine the effects of dietary Zn supplied in practical diets on the pond-raised hybrid snakehead (Channa maculate ♀ × C. argus ♂). Five extruded diets were supplemented with different Zn sulfate levels (analysed Zn values: 42.33, 65.79, 82.27, 100.41, and 120.18 mg kg-1). A total of 900 fish (initial weight 3.33 g) were divided into three net cages per treatment and fed twice daily to apparent satiety. The results indicated that dietary Zn influenced growth parameters, antioxidant capacity and innate immunity. The moisture and crude lipid contents of the whole body were significantly affected by dietary Zn concentration (P < 0.05). The whole-body, hepatic, and vertebral Zn concentrations were not significantly affected by dietary Zn level (P > 0.05). However, copper (Cu) content in the whole body, vertebrae, and liver increased and then decreased as dietary Zn increased (P < 0.05). The content of whole body Zn was significantly positively correlated with whole-body Fe, Mn (P < 0.01) and liver Cu (P < 0.05), and negatively correlated with whole-body Cu (P < 0.01). The content of liver Zn was positively correlated with liver Cu, Mn (P < 0.01), liver and whole body Fe (P < 0.05). Dietary Zn supplementation mitigated the generation of free radicals and improved the antioxidant capacity of hybrid snakehead. Plasma immune parameter activity and innate immune ability were both enhanced by appropriate dietary Zn levels. Liver Zn level was positively correlated with plasma C3 and TP (P < 0.05). Regression analysis of feed utilization, antioxidant and innate immunity parameters indicated that the optimum zinc concentration in a practical diet for fingerlings hybrid snakeheads ranged from 81.94 to 101.05 mg kg-1.

Effect of zinc and phytase supplementation on performance, immune response, digestibility and intestinal features in broilers fed a wheat-soybean meal diet

The aim of this study was to evaluate the effects of dietary zinc (Zn) supplementation on performance, immune responses and gastrointestinal tract features of broilers fed wheat-soybean meal diet. In addition, optimised dietary Zn level was estimated based on dose-response data. A total of 500 one-day-old male Ross-308 broiler chicks were randomly assigned to 10 dietary treatments with five replicates and ten birds per replicate in a 5 × 2 factorial arrangement of five graded (+40 mg/kg) dietary Zn levels with or without phytase (500 FTU/kg of diet) supplementation. By increasing dietary Zn concentration, final live body weight (LBW), daily weight gain (WG), feed intake (FI), and European Production Efficiency Factor (EPEF), antibody titres against the sheep red blood cell inoculation, cutaneous basophils hypersensitivity to PHA-P injection, jejunum villus height, and apparent dry matter digestibility (ADMD) increased with a significant linear trend. Phytase supplementation improved WG and ADMD and decreased pancreas and intestine relative weights. The interaction effects of dietary Zn concentration and phytase supplementation on the whole of evaluated traits were not significant. Optimum dietary Zn levels were estimated by the regression models at 70, 82, 98, and 110 mg/kg of diet for optimised EPEF and immunity, LBW and WG, appetites, and ADMD, respectively. It is concluded, in the broiler chickens fed wheat-soybean meal diet, Zn and phytase supplementation can improve growth performance, immune response, digestibility, and intestinal features. The Zn requirement is higher than the NRC (1994) recommendation. The efficacy of dietary Zn was not affected by dietary phytase supplementation. Highlights In the broilers fed wheat-soy diet: •Dietary Zn and phytase supplementation improve growth performance. •The Zn requirement is higher than the NRC recommendation.