Zinc overload in weaned pigs: tissue accumulation, pathology, and growth impacts

Antibiotic Residues and Zinc Concentrations in the Livers and Kidneys of Portuguese Piglets-Relationship to Antibiotic and Zinc Resistance in Intestinal Escherichia coli

Metal ions such as zinc and copper have been used as alternatives to antibiotics, to improve animal health and growth rates in pig farming. This study aims to determine antibiotic residues and Zn concentration in piglets' livers (n = 56) and kidneys (n = 60); and to examine the correlation between the use of Zn and antibiotics, and resistance to Zn and antibiotics of Escherichia coli isolated from piglets' faeces (n = 60). Samples were collected from randomly selected healthy piglets (n = 60); antibiotic residues were quantified by ultra-high-performance-liquid-chromatography time-of-flight mass spectrometry (UHPLC-ToF-MS); Zn was quantified using flame atomic absorption spectrometry (FAAS); microbiological methods were used for E. coli isolation, antibiotic susceptibility, and Zn minimal inhibitory concentration; and Real-Time PCR was used for gene detection. The presence of antibiotic residues and Zn concentrations in the liver was found to be negatively correlated, whilst no significant difference was observed in the kidney. In E. coli isolated from piglet faeces considered to be susceptible or multi-drug-resistant, no significant difference was found between Zn concentrations in the liver and in the kidney, which appears to indicate that Zn accumulated in the liver and in the kidney does not promote resistance to antibiotics in E. coli. The isolates showed tolerance to Zn which would suggest that antibiotic resistance and phenotypic tolerance to Zn in these isolates are not related. The genes zitB and zntA associated to Zn tolerance, were predominantly found in the more resistant Zn isolates. The findings provide insights on how Zn use in pig production maintains antibiotic resistance and metal tolerance in bacteria, with implications for One Health.

The Mechanism of Zinc Oxide in Alleviating Diarrhea in Piglets after Weaning: A Review from the Perspective of Intestinal Barrier Function

Weaning is one of the most challenging phases for piglets, and it is also the time when piglets are the most susceptible to diarrhea, which may result in significant economic losses for pig production. One of the dietary strategies for reducing post-weaning diarrhea (PWD) in piglets is to provide them with a pharmacological dose of zinc oxide (ZnO). However, excessive or long-term usage of high-dose ZnO has significant impacts on pig health and the ecological environment. Therefore, caution should be exercised when considering the use of high-dose ZnO for the prevention or treatment of PWD in piglets. In this paper, the significant role of zinc in animal health, the potential mode of action of ZnO in alleviating diarrhea, and the impact of innovative, highly efficient ZnO alternatives on the regulation of piglet diarrhea were reviewed to offer insights into the application of novel ZnO in pig production.

Long-term inhaling ultrafine zinc particles increases cardiac wall stresses elevated by myocardial infarction

The analysis of cardiac wall mechanics is of importance for understanding coronary heart diseases (CHD). The inhalation of ultrafine particles could deteriorate CHD. The aim of the study is to investigate the effects of cardiac wall mechanics on rats of myocardial infarction (MI) after long-term inhalation of ultrafine Zn particles. Cardiac wall stresses and strains were computed, based on echocardiographic and hemodynamic measurements. It was found that MI resulted in the significantly elevated stresses and the reduced strains. The short-term inhalation of ultrafine Zn particles decreased stresses and increased strains in MI rats, but the long-term inhalation had the opposite effects. Hence, the short-term inhalation of ultrafine Zn particles could alleviate the MI-induced LV dysfunction while the long-term inhalation impaired it.

Impact of zinc supplementation on phenotypic antimicrobial resistance of fecal commensal bacteria from pre-weaned dairy calves

The objective of this study was to evaluate the impact of dietary zinc supplementation in pre-weaned dairy calves on the phenotypic antimicrobial resistance (AMR) of fecal commensal bacteria. A repository of fecal specimens from a random sample of calves block-randomized into placebo (n = 39) and zinc sulfate (n = 28) groups collected over a zinc supplementation clinical trial at the onset of calf diarrhea, calf diarrheal cure, and the last day of 14 cumulative days of zinc or placebo treatment were analyzed. Antimicrobial susceptibility testing was conducted for Enterococcus spp. (n = 167) and E. coli (n = 44), with one representative isolate of each commensal bacteria tested per sample. Parametric survival interval regression models were constructed to evaluate the association between zinc treatment and phenotypic AMR, with exponentiated accelerated failure time (AFT) coefficients adapted for MIC instead of time representing the degree of change in AMR (MIC Ratio, MR). Findings from our study indicated that zinc supplementation did not significantly alter the MIC in Enterococcus spp. for 13 drugs: gentamicin, vancomycin, ciprofloxacin, erythromycin, penicillin, nitrofurantoin, linezolid, quinupristin/dalfopristin, tylosin tartrate, streptomycin, daptomycin, chloramphenicol, and tigecycline (MR = 0.96-2.94, p > 0.05). In E. coli, zinc supplementation was not associated with resistance to azithromycin (MR = 0.80, p > 0.05) and ceftriaxone (MR = 0.95, p > 0.05). However, a significant reduction in E. coli MIC values was observed for ciprofloxacin (MR = 0.17, 95% CI 0.03-0.97) and nalidixic acid (MR = 0.28, 95% CI 0.15-0.53) for zinc-treated compared to placebo-treated calves. Alongside predictions of MIC values generated from these 17 AFT models, findings from this study corroborate the influence of age and antimicrobial exposure on phenotypic AMR.

Porous Zinc Oxide and Plant Polyphenols as a Replacement for High-Dose Zinc Oxide on Growth Performance, Diarrhea Incidence, Intestinal Morphology and Microbial Diversity of Weaned Piglets

The aim of this experiment is to evaluate the effects of adding porous zinc oxide, plant polyphenols, and their combination to diets without antibiotics and high-dose zinc oxide on the growth performance, diarrhea incidence, intestinal morphology, and microbial diversity of weaned piglets. A total of 150 Duroc × Landrace × Large White weaned piglets were allocated to one of five diets in a randomized complete block design with six replicates and five piglets per replicate. The experimental period was 42 d, divided into two feeding stages: pre-starter (0-14 d) and starter (14-42 d). In the pre-starter stage, the negative control group (NC) was fed a basal diet, the positive control group (PC) was fed a basal diet with 2000 mg/kg of zinc oxide, the porous zinc oxide group (PZ) was fed a basal diet with 500 mg/kg of porous zinc oxide, the plant polyphenol group (PP) was fed a basal diet with 1500 mg/kg of plant polyphenols, and the combination group (PZ + PP) was fed a basal diet with 500 mg/kg of porous zinc oxide and 1500 mg/kg of plant polyphenols. In the starter stage, the NC, PC, and PZ groups were fed a basal diet, while the PP and PZ + PP groups were fed a basal diet with 1000 mg/kg of plant polyphenols. The results showed that, (1) compared with the PZ group, adding plant polyphenols to the diet showed a trend of increasing the ADFI of weaned piglets from 14 to 28 d (p = 0.099). From days 28 to 42 and days 0 to 42, porous zinc oxide and the combination of porous zinc oxide and plant polyphenols added to the control diet improved the FCR to the level observed in pigs fed the PC diet. (2) Dietary PZ + PP tended to increase the jejunal villus height (VH) of weaned piglets (p = 0.055), and significantly increased the villus-height-to-crypt-depth ratio compared to the NC group (p < 0.05). (3) Compared with the NC group, PZ supplementation decreased the relative abundance of Firmicutes and increased the relative abundance of Bacteroidetes, and the relative abundance of Lactobacillus in the PZ and PZ + PP groups were both increased. In conclusion, porous zinc oxide and plant polyphenols may have synergistic effects in modulating intestinal health in weaned piglets and be a potential alternative to high-dose zinc oxide.

Evaluation of a microencapsulated form of zinc oxide on weanling pig growth performance, fecal zinc excretion, and small intestinal morphology

A total of 300 pigs (DNA 200 × 400; initially 6.0 ± 0.08 kg body weight [BW]) were used in a 42-d study to evaluate a microencapsulated form of zinc oxide. At weaning, pigs were randomly allocated to pens, and pens were randomly assigned to dietary treatments with 5 pigs per pen and 12 pens per treatment. Dietary treatments were 1) negative control (CON; standard nursery diet containing 110 ppm Zn in the form of zinc sulfate from trace mineral premix); 2) control diet with 400 ppm added Zn from ZnO included in phases 1 and 2 (Low-ZnO); 3) control diet with 3,000 ppm added Zn from ZnO included in phase 1 and 2,000 ppm added Zn from ZnO included in phase 2 (High-ZnO); 4) control diet with 400 ppm added Zn from microencapsulated ZnO included in phases 1 and 2 (Low-MZnO; Vetagro S.p.A., Reggio Emilia, Italy); 5) control diet with 3,000 ppm added Zn from microencapsulated ZnO in phase 1 and 2,000 ppm added Zn from microencapsulated ZnO in phase 2 (high-MZnO; Vetagro S.p.A., Reggio Emilia, Italy). On days 10 and 28, fecal samples from 2 pigs per pen were collected for fecal Zn concentrations, and on day 28, 30 pigs (n = 6) were euthanized, and small intestinal tissues were collected to evaluate morphology. For the entire treatment period (days 0 to 28) there was no evidence of differences in average daily gain (ADG), average daily feed intake (ADFI), or G:F (P > 0.05). During the common phase 3 (days 28 to 42) pigs fed the negative control, High-MZnO, or Low-MZnO had improved (P < 0.0001) ADG and ADFI compared to pigs fed High- or Low-ZnO. For the entire experiment (days 0 to 42), pigs fed Low-ZnO or High-ZnO had reduced (P < 0.0001) ADG compared to those fed the negative control. A significant treatment × day interaction (P = 0.04) was observed for fecal Zn concentrations, where the level of Zn excreted in the feces was dependent on the sampling day in pigs fed a low level of ZnO or low level of microencapsulated ZnO. There was no evidence (P > 0.05) that small intestinal morphology differed significantly between treatments. In summary, feeding a microencapsulated form of ZnO did not alter piglet growth performance during the treatment period. Pigs fed a low level of ZnO or microencapsulated ZnO had reduced fecal Zn excretion by the end of the feeding period, but no significant impacts were observed on piglet small intestinal morphology.

Comparative efficacy of a novel Bacillus subtilis-based probiotic and pharmacological zinc oxide on growth performance and gut responses in nursery pigs

In this study, we assessed the efficacy of a novel Bacillus subtilis probiotic in improving growth performance and gut responses in comparison to pharmacological zinc oxide (ZnO) in nursery pigs. A total of 96 piglets were randomly assigned to four groups: Negative control (NC), Positive control (PC, 3000 mg Zn /kg feed), B.subtilis low dose (BS9-L, 2 × 10⁷ CFU/pig) and B.subtilis high dose (BS9-H, 2 × 10⁹ CFU/pig). Growth performance, diarrhea rate, gut mucosal gene expression and fecal microbial populations were evaluated. B.subtilis administration did not improve piglet bodyweight. BS9-L showed (P < 0.05) higher average daily gain (ADG) in Period 2 (D14-D28). BS9 groups had (P < 0.001) lower feed conversion ratio (FCR) in Period 2 (D14-D28) and overall. Like the ZnO-group, BS9 groups had lower (P < 0.01) diarrhea rate. A significant reduction (P < 0.05) in fecal E. coli, total coliforms, and an increase in lactic acid bacteria and Bacillus spp. in BS9 groups was observed. BS9 group had reduced (P < 0.05) mRNA levels of intestinal IL-8 and higher levels of MUC-1 and occludin and TJP-1 compared to negative control. These findings suggest that probiotic BS9, may promote growth performance, and ameliorate various indicators of intestinal health in piglets. Hence, it may serve as a prospective alternative to ZnO growth promoter in commercial swine production.

Evaluation of a Natural Phytogenic Formulation as an Alternative to Pharmaceutical Zinc Oxide in the Diet of Weaned Piglets

A natural phytogenic formulation (NPF) was tested as an alternative to pharmaceutical zinc oxide (ZnO) in weaned piglets with respect to growth performance, apparent total tract digestibility and faecal microbiota composition and metabolic activity. Two dietary NPF levels (NPF: 1000 and 2000 mg/kg diet) were compared to a positive control (ZnO: 3000 mg ZnO/kg diet) and a negative control (CON: no added ZnO or NPF) using 84 weaned piglets from 29 d to 78 d (days of age). Feed conversion ratio was improved (p < 0.05) in ZnO and NPF piglets were compared to CON at 50 d. Dry matter, organic matter and crude protein (p < 0.05) digestibility was improved in NPF piglets compared to CON at 57 d. Compared to CON, NPF inclusion reduced E. coli (p < 0.05) and increased C. leptum subgroup (p < 0.01) at 57 d and 78 d, and reduced C. perfringens subgroup (p < 0.05; at 78 d). The ZnO reduced (p < 0.001) E. coli and C. perfringens subgroup (p < 0.01) compared to CON at 78 d. Moreover, ZnO and NPF reduced molar ratios of branched chain volatile fatty acids (p < 0.05) compared to CON, while NPF also increased butyric acid (p < 0.05) at 78 d. In conclusion, the NPF appeared to be a promising alternative to pharmaceutical doses of ZnO.

Determination of the optimal dietary zinc content for pigs between 10 and 30 kg body weight

The Zn requirement of pigs immediately after weaning is more investigated compared to the Zn requirement in the growth period between 10 and 30 kg. Unabsorbed and excessive dietary Zn is excreted mainly through feces, and spreading pig slurry to fields can cause environmental issues because high levels of Zn can impair plant growth and contribute to the development of antimicrobial resistance genes in microorganisms. Therefore, more precise knowledge of Zn requirements and dietary Zn recommendations is important. The present study investigated the optimal dietary Zn content for 10- to 30-kg pigs. The study used 150 pigs weaned at 28 d of age (day 0) and supplied with 1,474 mg dietary Zn/kg the first 2 wk post-weaning. After 2 wk, pigs were randomly distributed according to body weight (BW; 10.1 ± 0.3 kg) and sex, to individually housing, and fed a diet supplemented with either 0, 30, 60, 120, or 240 mg Zn/kg (from ZnO), resulting in total dietary Zn contents of 80, 92, 117, 189, and 318 mg/kg until week 6 post-weaning. BW, feed intake, and fecal scores were recorded, and samples of blood (weeks 2, 3, 5, and 6) and tissues (week 6) were collected. The feed intake, growth, feed efficiency, relative weight of the pancreas and liver, Zn concentration in the liver, and pancreatic digestive enzyme activity were unaffected by dietary Zn content (P > 0.12). The serum Zn level decreased (P < 0.01) by up to 24% from weeks 2 to 3. The serum Zn concentrations in weeks 5 and 6 were similar to in week 2 when 117, 189, and 318 mg Zn/kg were provided, while with 80 and 92 mg Zn/kg the serum Zn concentration was lower (P < 0.01) than in week 2. The serum Zn concentration reached a plateau in weeks 5 and 6, and breakpoints were calculated at 126 ± 17 and 102 ± 6 mg Zn/kg, respectively. Bone Zn status was greater (P < 0.01) with 189 than 80 mg Zn/kg and a breakpoint was calculated at 137 ± 19 mg Zn/kg. According to performance, the Zn requirement for 10- to 30-kg pigs can be fulfilled with 80 mg total Zn/kg, but based on serum and bone Zn status, the optimal total dietary Zn content is 102 to 137 mg/kg. The latter corresponds to a daily Zn intake (requirement) of 103 to 138 mg when calculated from the average feed intake during weeks 3 to 6 (1,005 g/d). Importantly, the presented results are obtained in pigs supplied with 1,474 mg Zn/kg from ZnO the first 2 wk post-weaning and a high level of phytase (1,000 phytase units) in the diet throughout the experiment.

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.

Bioavailability of Different Zinc Sources in Pigs 0-3 Weeks Post-Weaning

The bioavailability of dietary zinc (Zn) in pigs may differ according to the Zn source and is affected by other components in the diet. The aim was to determine the biomarkers of Zn bioavailability (apparent total tract digestibility of Zn and serum Zn status) following six different sources of added Zn and their effect on the performance and faecal consistency score in piglets 0-3 weeks after weaning on day 28. The sources of Zn were Zn oxide (ZnO), Zn sulfate (ZnSO₄), porous ZnO, Zn-glycinate, amino acid-bound Zn and hydroxy covalent-bound Zn added at 100 mg/kg (ZnO and ZnSO₄ also added at 1000 mg/kg), in a total of eight treatments (n = 12/treatment). Pigs were individually housed, and titanium dioxide was included as an indigestible marker in the feed. The digestibility of Zn on day 14 post-weaning was negative for all six Zn sources at 100 mg Zn/kg, indicating insufficient Zn supply. The digestibility of Zn differed according to the Zn source, but the digestibility of Zn from ZnO and ZnSO₄ did not differ between processed inorganic or chelated organic sources of Zn. However, the differences in Zn digestibility between Zn sources were not reflected as differences in the serum Zn status, feed intake, gain or probability of diarrhoea.

Enterotoxigenic Escherichia coli infection of weaned pigs: Intestinal challenges and nutritional intervention to enhance disease resistance

Enterotoxigenic Escherichia coli (ETEC) infection induced post-weaning diarrhea is one of the leading causes of morbidity and mortality in newly weaned pigs and one of the significant drivers for antimicrobial use in swine production. ETEC attachment to the small intestine initiates ETEC colonization and infection. The secretion of enterotoxins further disrupts intestinal barrier function and induces intestinal inflammation in weaned pigs. ETEC infection can also aggravate the intestinal microbiota dysbiosis due to weaning stress and increase the susceptibility of weaned pigs to other enteric infectious diseases, which may result in diarrhea or sudden death. Therefore, the amount of antimicrobial drugs for medical treatment purposes in major food-producing animal species is still significant. The alternative practices that may help reduce the reliance on such antimicrobial drugs and address animal health requirements are needed. Nutritional intervention in order to enhance intestinal health and the overall performance of weaned pigs is one of the most powerful practices in the antibiotic-free production system. This review summarizes the utilization of several categories of feed additives or supplements, such as direct-fed microbials, prebiotics, phytochemicals, lysozyme, and micro minerals in newly weaned pigs. The current understanding of these candidates on intestinal health and disease resistance of pigs under ETEC infection are particularly discussed, which may inspire more research on the development of alternative practices to support food-producing animals.

Exposure to zinc induces lysosomal-mitochondrial axis-mediated apoptosis in PK-15 cells

Zinc (Zn), a kind of metallic element, can cause poisonous effects on host physiology when its excess exposure. Lysosomes and mitochondria are the toxic targets of heavy metals, and the lysosomal-mitochondrial axis is also verified to take part in apoptosis, but the related underlying mechanisms in Zn-induced cytotoxicity remain undefined. Here, we identified that excess Zn could cause cell damage in PK-15 cells accompanied by the lysosomal and mitochondrial dysfunction, with the evidence by the elevated levels of cathepsin B/D (CTSB/CTSD) in cytoplasm and decrease of Lyso-Tracker Red signal, red fluorescence intensity of AO staining, mitochondrial complex enzyme activities and ATP production. Additionally, the number of Annexin V⁺/PI^--stained cells, apoptosis-related genes (Bax, Bid, Bak1, Caspase-9, and Caspase-3) and proteins levels of Bax, Bak1, Caspase-9, cleaved Caspase-3 and cytoplasmic Cyt C were signally elevated under Zn exposure, while the protein levels of Bcl2 and mitochondrial Cyt C were observably decreased. Importantly, Pepstatin A (the activity inhibitor of CTSD) and RNA interference of CTSD (si-CTSD) was used to reduce the release of lysosomal CTSD to the cytoplasm, which could signally alleviated Zn-induced mitochondrial damage and apoptosis. In summary, these results suggested that Zn could induced lysosomal and mitochondrial dysfunction in PK-15 cells, and the CTSD played an important role in Zn-induced lysosomal-mitochondrial axis-mediated apoptosis. Our results provided a new insight in Zn-induced toxicology, which for protecting the ecological environment and public health.

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

Simple Summary

Piglets 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.

Abstract

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.

Importance of Zinc Nanoparticles for the Intestinal Microbiome of Weaned Piglets

The scientific community is closely monitoring the replacement of antibiotics with doses of ZnO in weaned piglets. Since 2022, the use of zinc in medical doses has been banned in the European Union. Therefore, pig farmers are looking for other solutions. Some studies have suggested that zinc nanoparticles might replace ZnO for the prevention of diarrhea in weaning piglets. Like ZnO, zinc nanoparticles are effective against pathogenic microorganisms, e.g., Enterobacteriaceae family in vitro and in vivo. However, the effect on probiotic Lactobacillaceae appears to differ for ZnO and zinc nanoparticles. While ZnO increases their numbers, zinc nanoparticles act in the opposite way. These phenomena have been also confirmed by in vitro studies that reported a strong antimicrobial effect of zinc nanoparticles against Lactobacillales order. Contradictory evidence makes this topic still controversial, however. In addition, zinc nanoparticles vary in their morphology and properties based on the method of their synthesis. This makes it difficult to understand the effect of zinc nanoparticles on the intestinal microbiome. This review is aimed at clarifying many circumstances that may affect the action of nanoparticles on the weaning piglets' microbiome, including a comprehensive overview of the zinc nanoparticles in vitro effects on bacterial species occurring in the digestive tract of weaned piglets.

Effects of the methionine hydroxyl analog chelated microminerals on growth performance, antioxidant status, and immune response of growing-finishing pigs

This study aimed to investigate the effects of methionine hydroxyl analog chelated microminerals (MHA-M) replacing inorganic microminerals (ITMs) on the growth performance, fecal microminerals concentrations, immune function, and antioxidant status in growing-finishing pigs; 253 pigs (average 33.68 kg body weight) were randomly assigned to six treatments with six replicates each treatment: (1) ITM: a basal diet with Cu, Fe, Mn, and Zn from sulfates providing 20, 100, 40, and 60 mg/kg; (2-6): 1/5MHA-M, 2/5MHA-M, 3/5MHA-M, 4/5MHA-M, and MHA-M was replaced with 20%, 40%, 60%, 80%, and 100% MHA-M. Results showed that the average daily gain (ADG) in the 1/5MHA-M and 2/5MHA-M was greater than other groups in the whole period. Fecal Cu, Fe, Mn, and Zn concentrations had decreased as the intake of trace minerals decreases. The ITM group decreased the fecal Zn concentration on Days 35, 70, and 91, and Fe concentration on Day 70, and increased the Mn concentration on Day 70 compared with MHA-M group. Pigs fed 1/5MHA-M, 2/5MHA-M, and MHA-M had a higher immune function and antioxidant status in serum compared with ITM, 3/5MHA-M, and 4/5MHA-M on Day 35. In conclusion, treatment with 1/5MHA-M and 2/5MHA-M could reduce the excretion of fecal microminerals and improve the immune function and antioxidant capacity compared with the ITM group.

Dietary Pharmacological Zinc and Copper Enhances Voluntary Feed Intake of Nursery Pigs

The objective of the three experiments herein were to characterize the effect of pharmacological zinc and copper concentrations on nursery pig feed intake, stomach ghrelin, energy and nutrient digestibility, and mineral retention in post-weaned pigs. In Expt. 1, 300 weaned pigs were allotted across three dietary treatments (n = 10 pens/treatment) and fed in two diet phases (P1 and P2) lasting 7 and 14 days, respectively. Treatments were: (1) Control diet with no pharmacological minerals in P1 and P2, CON; (2) CON + 3,000 mg/kg Zn and 200 mg/kg Cu (P1), no pharmacological minerals in P2, ZC-CON; and (3) CON + 3,000 mg/kg Zn and 200 mg/kg Cu (P1), CON + 2,000 mg/kg Zn and 200 mg/kg Cu (P2); ZC. Over the 21-day test period, ZC pigs had 15% higher ADG and 13–24% ADFI compared to the CON and ZC-CON pigs (P &lt; 0.05). ZC-CON and ZC pig daily feed intakes were 29 and 73% higher by day 5 and 7 post-weaning, respectively, compared to the CON pigs (P &lt; 0.0001). However, removing pharmacological minerals in P2 abruptly decreased ZC-CON daily feed intake within 24 h to similar intakes as the CON compared to the ZC pigs (0.17, 0.14, and 0.22 kg/d, respectively, P &lt; 0.05). Dietary pharmacological minerals increased stomach fundus ghrelin-positive cells than CON pigs at day 7 (P = 0.005) and day 21 (P &lt; 0.001). However, fasting plasma total and acyl-ghrelin concentrations did not differ from a control in response to zinc oxide daily drenching (Expt. 2). Expt. 3 showed that zinc and copper to have moderate to low retention; however, pharmacological zinc and copper diets increased zinc (P &lt; 0.05) and copper retention (P = 0.06) after 28 days post-weaning compared to control pigs. Pharmacological zinc and copper did not improve digestible energy, metabolizable energy or nitrogen balance. Altogether, dietary pharmacological zinc and copper concentrations improve growth rates and mineral retention in nursery pigs. This improved performance may partially be explained by increased stomach ghrelin abundance and enhanced early feed intake in newly weaned pigs fed pharmacological concentrations of zinc and copper.

Osteoporosis in swine

ABSTRACT: Forty-six pigs presented muscle weakness, hind limb paresis and paralysis, weight loss, lateral recumbency, and death in a clinical course of 7 to 10 days. Two pigs were necropsied and exhibited bone fragility, bone callus formation, and multiple fractures in the limbs, ribs, and vertebrae. Microscopically, there was a diffuse and marked decrease in thickness and number of trabeculae. These were disconnected, with a “free-floating” appearance, while the cortex of the long bones was thinned, with an increase of the cortical porosity by enlargement of Haversian canals and endosteal erosion and decreased osteoblastic activity. Flame atomic absorption spectrometry in liver samples revealed significant zinc overload (>2300ppm) and copper deficiency (<33.1ppm). In this communication, we present the first pathologic description of an outbreak of osteoporosis in pigs, and we also provide a brief review of metabolic bone diseases in pigs.

The effects of mushroom powder and vitamin D2 -enriched mushroom powder supplementation on the growth performance and health of newly weaned pigs

A complete randomised block design experiment was conducted to examine the effects of mushroom powder (MP) and vitamin D₂ -enriched mushroom powder (MPD₂ ) on growth performance, faecal scores, coefficient of apparent total tract digestibility (CATTD) of nutrients and selected microflora in weaned pigs up to day 35 post-weaning. One hundred and ninety-two weaned pigs (7.8kg [SD 1.08kg]) were blocked according to live weight, sex and litter of origin and randomly assigned to the following: (T1) control diet; (T2) control diet +MP; (T3) control diet + MPD₂ ; and (T4) control diet +zinc oxide (ZnO) (n = 12 replicates/treatment). Mushroom powders were included at 2 g/kg of feed achieving a β-glucan content of 200ppm. ZnO was included at 3100 mg/kg feed and halved to 1550 mg/kg after 21 days. Vitamin D content was enhanced in MPD₂ using synthetic UVB exposure to obtain a vitamin D₂ level of 100 µg/kg of feed. Faecal samples were collected on day 14 for microbial and nutrient digestibility analysis. There was no difference (p > 0.05) in ADG, G:F, faecal scores, microbial populations and CATTD of nutrients in pigs supplemented with MP or MPD₂ compared with the control diet. The supplementation of MP and MPD₂ caused a reduction (p < 0.05) in feed intake compared with the control and ZnO diet throughout the 35-day experimental period. ZnO supplementation increased ADG and ADFI (p < 0.05) during the first period (D0-21) compared with pigs offered MP and MPD₂ . In conclusion, MP and MPD₂ supplementation resulted in similar ADG, G:F, faecal scores compared with the control but were not comparable to ZnO, mainly due to a reduction in feed intake.

Effect of Zinc Source and Level on Growth Performance and Zinc Status of Weaned Piglets

The aim of this study was to evaluate the effect of zinc (Zn) supplementation in different commercial forms on the growth performance, health status, and Zn balance of weaners in field conditions. The animals were fed pre-starter (from the 28th to 47th day of life) and starter (from the 48th to 74th day of life) mixtures differing in Zn form and concentration. Group I was given ZnSO4 at 150 mg kg-1; Group II received pre-starter zinc oxide (ZnO) at 3000 mg kg-1 and starter at 150 mg kg-1; and Group III was given 150 mg kg-1 of zinc oxide nanoparticles (nZnO). We found that the average daily gain in Group I was significantly lower, compared to Groups II and III. A commonly accepted level of Zn (150 mg kg-1) as nZnO can be recommended, instead of therapeutic doses of Zn preparations with the same efficiency. Moreover, a lower level of Zn in the diet can prevent the excessive accumulation of this element in waste and, thus, reduce environmental damage.

Effects of feeding diets containing low crude protein and coarse wheat bran as alternatives to zinc oxide in nursery pig diets

Two experiments were conducted to determine the effects of crude protein (CP) level in diets containing coarse wheat bran (CWB) with or without pharmacological levels of Zn (provided by zinc oxide: ZnO) on growth performance and fecal DM of nursery pigs. In experiment 1, 360 barrows (Line 200 × 400, DNA, Columbus, NE, initially 5.6 kg) were allotted to 1 of 6 dietary treatments from d 0 to 21 after weaning with 5 pigs per pen and 12 pens per treatment. Treatments included a positive control diet (21% CP) with 3,000 mg/kg Zn in phase 1 and 2,000 mg/kg in phase 2; negative control (21% CP) with 110 mg/kg added Zn, and 4 diets containing 4% CWB and 110 mg/kg added Zn formulated to contain 21%, 19.5%, 18%, or 16.5% CP. The 2 control diets and 21% CP CWB diet contained 1.40% standardized ileal digestible (SID) Lys in phase 1 and 1.35% SID Lys in phase 2, while the 19.5%, 18%, and 16.5% CP diets contained 1.33, 1.25 and 1.20% Lys, respectively, in both phases. Pigs fed the positive control diet containing pharmacological ZnO had increased (P < 0.05) ADG and G:F compared with the negative control and the 21% CP CWB diet. Reducing CP (concurrently with SID Lys) in diets containing CWB decreased ADG and G:F (linear, P = 0.002); however, fecal DM increased (linear, P = 0.005). In experiment 2, two groups of 300 and 350 pigs, initially 7.0 and 6.2 kg, respectively, were used with 5 pigs per pen and 26 pens per treatment. The objective was to determine if adding back essential AA would improve growth performance of pigs fed the low CP diets. All dietary treatments were fed for 13 days, contained 4% CWB, and consisted of: (1) positive control with 2,000 mg/kg of Zn and 21% CP (1.35% SID Lys); (2) no ZnO and 21% CP; and 3 diets with no ZnO formulated to 18% CP and (3) 1.2% SID Lys; (4) 1.35% SID Lys by the addition of feed grade amino acids (AA), and (5) diet 4 with non-essential amino acids (NEAA; Gly and Glu). Pigs fed 21% CP with ZnO had increased (P = 0.001) ADG compared to those fed 18% CP (1.35% SID Lys) with high levels of feed grade amino acids or those fed the reduced SID Lys (1.2%) diet. Overall, G:F was improved (P < 0.001) for pigs fed 21% CP diets and those fed the 18% CP diet with NEAA compared to pigs fed 1.2% SID Lys and pigs fed high levels of feed grade amino acids. Fecal DM was increased for pigs fed the reduced SID Lys diet. In summary, pharmacological levels of Zn improve pig growth performance, but reducing CP (and subsequently SID Lys) decreased nursery pig growth performance.

Recent Advances in Understanding the Influence of Zinc, Copper, and Manganese on the Gastrointestinal Environment of Pigs and Poultry

Simple Summary

Pigs and poultry, similar to humans, need regular consumption of zinc, copper, and manganese for normal functioning. To ensure adequate dietary intake, and prevent deficiency, their diets are supplemented with sufficient, often excessive, levels of these minerals or even at higher levels, which have been associated with improvements in their health and/or growth. However, if provided in excess, mineral quantities beyond those required are simply excreted from the animal, which is associated with negative consequences for the environment and even the development of antimicrobial resistance. Therefore, it is of great interest to better understand the dynamics of zinc, copper, and manganese in the intestine of pigs and poultry following consumption of supplemented diets, and how the requirements and benefits related to these minerals can be optimized and negative impacts minimized. The intestine of pigs and poultry contains vast numbers of microorganisms, notably bacteria, that continually interact with, and influence, their host. This review explores the influence of zinc, copper, and manganese on these interactions and how novel forms of these minerals have the potential to maximize their delivery and benefits, while limiting any negative consequences.

Abstract

Zinc, copper, and manganese are prominent essential trace (or micro) minerals, being required in small, but adequate, amounts by pigs and poultry for normal biological functioning. Feed is a source of trace minerals for pigs and poultry but variable bioavailability in typical feed ingredients means that supplementation with low-cost oxides and sulphates has become common practice. Such trace mineral supplementation often provides significant ‘safety margins’, while copper and zinc have been supplemented at supra-nutritional (or pharmacological) levels to improve health and/or growth performance. Regulatory mechanisms ensure that much of this oversupply is excreted by the host into the environment, which can be toxic to plants and microorganisms or promote antimicrobial resistance in microbes, and thus supplying trace minerals more precisely to pigs and poultry is necessary. The gastrointestinal tract is thus central to the maintenance of trace mineral homeostasis and the provision of supra-nutritional or pharmacological levels is associated with modification of the gut environment, such as the microbiome. This review, therefore, considers recent advances in understanding the influence of zinc, copper, and manganese on the gastrointestinal environment of pigs and poultry, including more novel, alternative sources seeking to maintain supra-nutritional benefits with minimal environmental impact.

Towards Zero Zinc Oxide: Feeding Strategies to Manage Post-Weaning Diarrhea in Piglets

Simple Summary

Zinc oxide (ZnO) supplementation at pharmacological doses in post-weaning piglets is a consolidated practice that allows efficient control of post-weaning diarrhea (PWD), a condition exacerbated by Escherichia coli F4 (K88) infections. Far from being completely elucidated, the multifactorial ZnO mechanism of action is in all likelihood exerted at the gastrointestinal level. However, increasing environmental concerns are arising from prolonged ZnO use. This article reviews the utilization of ZnO in piglets, the biological rationale behind its powerful activity, and the emerging threats that are leading towards a significant reduction in its use. Finally, a wide analysis of the strengths and weaknesses of innovative alternative strategies to manage PWD at the nutritional level is given.

Abstract

Zinc oxide (ZnO) at pharmacological doses is extensively employed in the pig industry as an effective tool to manage post-weaning diarrhea (PWD), a condition that causes huge economic losses because of its impact on the most pivotal phase of a piglet’s production cycle. In a multifactorial way, ZnO exerts a variety of positive effects along the entire gastrointestinal tract by targeting intestinal architecture, digestive secretions, antioxidant systems, and immune cells. ZnO also has a moderate antibacterial effect against Escherichia coli F4 (K88), the main causative agent of PWD. However, the environmental impact of ZnO and new emerging threats are posing serious questions to the sustainability of its extensive utilization. To work towards a future free from pharmacological ZnO, novel nutritional approaches are necessary, and many strategies have been investigated. This review article provides a comprehensive framework for ZnO utilization and its broad mode of action. Moreover, all the risks related to pharmacological ZnO levels are presented; we focus on European institutions’ decisions subsequently. The identification of a novel, complete solution against PWD should be accompanied by the adoption of holistic strategies, thereby combining good management practices to feeding approaches capable of mitigating Escherichia coli F4 (K88) infections and/or lowering ZnO utilization. Promising results can be obtained by adjusting diet composition or employing organic acids, natural identical compounds, polyphenol-rich extracts, prebiotics, and probiotics.

Chronic pancreatitis in farmed pigs fed excessive zinc oxide

Most of the pigs on a farm in Aichi Prefecture, Japan had chronic diarrhea and severe wasting. The pigs had consumed 8,000 ppm zinc oxide (ZnO) as a feed additive. The pancreas of each of 4 autopsied pigs was less than half the normal size. Acinar cells were considerably decreased. Epithelial duct-like cells were increased and tested positive for cytokeratin AE1/AE3, Ki67, PGP9.5, and Sox9. Pancreatic islet cells were decreased and shrunken. The α and δ cells were relatively decreased, and their distribution was abnormal. Islet cells were positive for PGP9.5. The livers and kidneys had high accumulations of zinc (Zn; 788 µg/g and 613 µg/g, respectively). Copper was deficient in the liver, likely as a result of Zn poisoning. Our immunohistologic examination suggested that the high dose of ZnO could influence the function of islet cells in addition to that of acinar cells. Given that colistin sulfate has been banned as a feed additive in order to reduce antimicrobial use in Japan, the use of ZnO in the livestock industry is expected to increase. Zn supplementation of pig feed must be monitored to prevent Zn poisoning and contamination of soil and water.