Dietary Zn Supplementation Research Articles

Abstract We038: Metal-organic frameworks as next-generation cardiac therapeutics

Background: Zinc (Zn) is an essential trace element for the normal functioning of the heart. Long-term dietary supplementation of Zn has been shown to improve cardiac function and prevent myocardial damage caused by ischemia-reperfusion injury. However, the major limitation in delivering Zn to the cardiac tissue is the off-targeted absorption and the duration of treatment to achieve a therapeutic effect. Hypothesis: Cardiac-targeted delivery of trace elements like Zn may attenuate myocardial damage caused by ischemia-reperfusion injury, improve cardiac function, and exert a cardioprotective effect. Methods: Zn-based metal-organic frameworks (ZIF-NPs) were fabricated and tested on Microvascular Endothelial Cells (MVECs), and human-induced pluripotent derived cardiomyocytes (hiCMs) for cytoprotective effect against hypoxic stress using Live/dead assay and multi-electrode array (MEA) analysis respectively. The in vivo efficacy of ZIF-NPs was tested in the rodent myocardial infarction (MI) model and cardiac function was assessed via M-mode echocardiography. Results: The fabricated ZIF-NPs were biocompatible and showed significant intracellular uptake causing the induction of cytoprotective metallothioneins. ZIF-NP treatment showed enhanced cell survival in serum-starved MVECs and exhibited pro-angiogenic effects in vitro. Similarly, hiCMs treated with ZIF-NPs displayed enhanced endurance and electrophysiological function, when subjected to hypoxic stress and protected the cells against ROS-induced DNA damage. Intramyocardial delivery of ZIF-NPs in the cardiac tissue improved cardiac function and attenuated fibrosis post-MI. Conclusions: ZIF-NPs exerted a pro-survival, cytoprotective response in both in vitro and in vivo conditions. Our study highlights the significance of cardiac targeted Zn delivery by ZIF-NPs for cardioprotection as next-generation cardiac therapeutics.

197 Effects of dietary zinc supplementation strategy on immune response, bacterial load and disease severity in growing gilts infected with Mycoplasma hyopneumoniae.

Abstract The objective of this study was to assess impacts of dietary zinc (Zn) supplementation strategy on immune response, bacterial clearance, and disease severity in growing gilts infected with Mycoplasma hyopneumoniae. Weaned gilts [n = 96; 21-d old; initial body weight (BW) = 6.94 kg], were used in a 63-d experiment which consisted of a pre- (d 0-35) and post- (d 35-63) M. hyopneumoniae challenge. On d 0 (-35 d post-inoculation; dpi), gilts were confirmed negative for M. hyopneumoniae and PRRSv and assigned randomly to 1 of 2 dietary treatments with 8 pens/treatment and 6 gilts/pen. Treatments were: 1) Control; 125 mg/kg Zn from ZnSO4, and 2) Zn-blend; 125 mg/kg Zn with 50 mg/kg Zn from Zn-amino acid complex (ZnAA) and 75 mg/kg Zn from ZnSO4. Dietary treatments were fed in 4-phases with pharmacological levels of zinc oxide included in the first 2 phases. Phase 1 (d 0) control and Zn-blend diets contained 3,121 and 3,256 mg/kg total Zn, respectively. Phase 2 (d 0-14) control and Zn-blend diets contained 3,657 and 3,593 mg/kg total Zn, respectively. Phases 3 (d 14-35) and 4 (d 35-63) control and Zn-blend diets contained 213 and 193 mg/kg and 229 and 212 mg/kg total Zn, respectively. At 0 and 1 dpi, all gilts were inoculated intratracheally with 10 mL of a lung homogenate containing 1×105 CCU/mL of M. hyopneumoniae strain 232. Blood and tracheal secretions were collected on -35, 0, 7, 14, 21, 28 dpi. Blood samples were evaluated for antibody detection, and tracheal secretions were analyzed by PCR. Number of coughs were recorded daily from 7 to 28 dpi. At 28 dpi, gilts were humanely euthanized, and bronchoalveolar lavage fluid (BALF) and macroscopic lung lesion observations were collected. Gross lung lesions were scored, and lung tissues were fixed for histopathology. Normally distributed data were analyzed in a generalized linear model with the fixed effect of diet and repeated measures for days post-inoculation. Non-normal data were analyzed using a Mann Whitney U Test using the NPAR1WAY procedure of SAS with a fixed effect of diet or a Chi-square test. Gilts consuming control diets tended (21.68 vs. 20.90 Ct, P = 0.08) to have less relative bacterial load than those consuming Zn-blend diets, over time. No differences in mean sample-to-positive ratio or proportion of gilt seroconversion (P > 0.05) were detected between treatments. There were no differences in mean concentrations of IL-1α, IL-1β, IL-6, IL-8, IL-10 (P > 0.05) in BALF for gilts consuming control or Zn-blend diets. There were no differences in mean macroscopic (P = 0.73) or microscopic (P = 0.67) lung scores, and coughing index score (P = 0.25) over the entire period between gilts consuming the different dietary Zn supplementation strategies. In conclusion, growing gilts consuming diets containing different Zn sources exhibited similar signs of infection during the acute phase of a M. hyopneumoniae infection.

Dietary Zinc Supplementation in Steers Modulates Labile Zinc Concentration and Zinc Transporter Gene Expression in Circulating Immune Cells.

Zinc (Zn) is critical for immune function, and marginal Zn deficiency in calves can lead to suboptimal growth and increased disease susceptibility. However, in contrast to other trace minerals such as copper, tissue concentrations of Zn do not change readily in conditions of supplementation or marginal deficiency. Therefore, the evaluation of Zn status remains challenging. Zinc transporters are essential for maintaining intracellular Zn homeostasis, and their expression may indicate changes in Zn status in the animal. Here, we investigated the effects of dietary Zn supplementation on labile Zn concentration and Zn transporter gene expression in circulating immune cells isolated from feedlot steers. Eighteen Angus crossbred steers (261 ± 14 kg) were blocked by body weight and randomly assigned to two dietary treatments: a control diet (58 mg Zn/kg DM, no supplemental Zn) or control plus 150 mg Zn/kg DM (HiZn; 207 mg Zn/kg DM total). After 33 days, Zn supplementation increased labile Zn concentrations (as FluoZin-3 fluorescence) in monocytes, granulocytes, and CD4 T cells (P < 0.05) but had the opposite effect on CD8 and γδ T cells (P < 0.05). Zn transporter gene expression was analyzed on purified immune cell populations collected on days 27 or 28. ZIP11 and ZnT1 gene expression was lower (P < 0.05) in CD4 T cells from HiZn compared to controls. Expression of ZIP6 in CD8 T cells (P = 0.02) and ZnT7 in B cells (P = 0.01) was upregulated in HiZn, while ZnT9 tended (P = 0.06) to increase in B cells from HiZn. These results suggest dietary Zn concentration affects both circulating immune cell Zn concentrations and Zn transporter gene expression in healthy steers.

Zinc intake ameliorates intestinal morphology and oxidative stress of broiler chickens under heat stress.

Zinc (Zn), an essential trace element for poultry, plays a crucial role in promoting growth, improving feed conversion efficiency, enhancing antioxidant activity, and preventing disease. This study investigated the impact of different levels and sources of dietary Zn supplementation on the growth performance, intestinal morphology and antioxidant activity of broiler chickens under heat stress conditions. In this experiment, 1024 Xueshan chickens were divided into eight groups and subjected to heat stress conditions with different levels of Zn supplementation (30 mg/kg, 60 mg/kg, and 90 mg/kg) using organic or inorganic sources. Our findings indicated that dietary Zn supplementation significantly increased the feed-to-weight ratio of broilers during the experimental period under heat stress. Moreover, Zn supplementation positively increased the villus height and villus width in the jejunum and ileum at 74 and 88 days old, with the 60 and 90 mg/kg groups outperforming other groups, and organic Zn was more effective than inorganic Zn. Furthermore, Zn supplementation significantly increased serum antioxidant levels, with higher superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-px) activities, and organic Zn was more effective than inorganic Zn. This study concludes that Zn supplementation is beneficial in mitigating the detrimental impacts of heat stress on broilers. The findings suggest that employing Zn as a strategy can enhance productivity in the poultry industry by positively influencing intestinal morphology and bolstering antioxidant activity to counteract potential stress.

Milk microbiome in the first month of lactation and at weaning from ewes supplemented with zinc pre- and postpartum.

Mastitis is an important disease with economic and welfare implications in both clinical and subclinical states. The aim of this research was to sequence the hypervariable V4 region of the 16S rRNA gene to describe the microbial diversity and taxonomy of milk from clinically healthy ewes (Rambouillet, WF = 9; Hampshire, BF = 5). Experimental ewes represented a subset of a larger study assessing the impacts of divergent dietary zinc (Zn) concentrations [1 × National Academics of Sciences, Engineering, and Medicine (NASEM) recommendations = CON or 3 × NASEM recommendations = ZnTRT] throughout late gestation and lactation. Milk was collected at four periods during early lactation (18 to 24h, 7 d, 14 d, and 21 d postpartum) and at weaning (84 ± 14 d postpartum). Somatic cell counts (SCC) were quantified, averaged, and classed (low: < 500 × 103; medium: 500 × 103 - 100 × 104; high: > 100 × 104 cells/mL). Milk samples (n = 67) were sequenced to identify bacteria and archaea; the most abundant phyla were Actinobacteria, Bacteroidetes, Cyanobacteria, Euryarchaeota, Firmicutes, Fusobacteria, Lentisphaerae, Proteobacteria, Spirochaetes, Tenericutes, Saccharibacteria TM7, and Verrucomicrobia. Mastitis pathogens were among the most relatively abundant genera, including Staphylococcus, Mannheimia, Corynebacterium, and Pseudomonas. Effects of breed, dietary Zn concentration, SCC class, and their two-way interactions on milk microbiome diversity and taxonomy were assessed within early lactation (using a repeated measures model) and weaning samples. Alpha-diversity metrics included Pielou's evenness, Faith's phylogenetic diversity, and Shannon's entropy indices. The main and interactive effects between Zn treatment, breed, SCC class, and period were variable in early lactation and not evident in weaning samples. Milk from BF ewes had increased Faith's phylogenetic diversity and Shannon's entropy, and differed in unweighted UniFrac composition (P ≤ 0.10). Milk from CON ewes had a reduced rate of composition change through early lactation (P = 0.02) indicating greater microbiome stability than ZnTRT ewe milk. These results support that milk is not sterile, and breed, dietary Zn concentration, and SCC class variably affect the milk microbiome. Findings from the current study provide important foundational insights into the effects of increased dietary Zn supplementation on longitudinal changes in the milk microbiome and associations with mammary gland health and mastitis.

Research Note: Relative bioavailability of zinc in zinc hydroxychloride for chicks

A chick assay was conducted to determine the effects of Zn source on performance and to establish a Zn relative bioavailability value (RBV) for a new source of Zn hydroxychloride. In the assay, 8-day-old chicks were fed a Zn-deficient soy protein concentrate diet supplemented with 0, 7, and 15 mg Zn/kg from feed grade ZnSO4 monohydrate for 14 d to establish a standard response curve. The same basal diet was supplemented with 3, 7, and 10 mg Zn/kg from a new Zn hydroxychloride (SAMZn). A second source of Zn hydroxychloride (IBZn) was supplemented at 10 mg Zn/kg as a direct comparison to the highest level of SAMZn. Weight gain increased (P < 0.05) with increasing Zn level, regardless of source. Weight gain of chicks fed 7 mg Zn/kg from SAMZn was not different (P > 0.05) from chicks fed 15 mg Zn/kg from ZnSO4. Weight gain was not different (P > 0.05) when comparing the 2 sources of Zn hydroxychloride supplemented at 10 mg Zn/kg. Tibia ash Zn and total tibia Zn were increased (P < 0.05) by all Zn sources and responded linearly (P < 0.05) to Zn supplementation from ZnSO4 and SAMZn. Total tibia Zn concentration was not different (P > 0.05) for chicks fed 10 mg Zn/kg from either source of Zn hydroxychloride. Multiple linear regression of total tibia Zn on supplemental Zn intake (R2 = 0.95) resulted in a RBV of 115% for SAMZn compared with ZnSO4 (set at 100%). The RBV of SAMZn was higher (P < 0.05) than ZnSO4. In conclusion, relative bioavailability of Zn (based on tibia Zn) in Zn hydroxychloride from SAMZn was higher than feed grade ZnSO4 based on multiple regression slope-ratio analysis and was similar to that of IBZn Zn hydroxychloride based on tibia Zn responses to 10 mg/kg supplemental dietary Zn.

Dietary zinc inadequacy affects neurotrophic factors and proteostasis in the rat brain

Zinc (Zn) deficiency has many adverse effects, including growth retardation, loss of appetite, vascular diseases, cognitive and memory impairment, and neurodegenerative diseases. In the current study, we investigated the hypothesis that dietary Zn inadequacy affects neurotrophic factors and proteostasis in the brain. Three-week-old Wistar/Kyoto male rats were fed either a Zn-deficient diet (D; < 1 mg Zn/kg diet; n = 18) or pair-fed with the control diet (C; 48 mg Zn/kg diet; n = 9) for 4 weeks. Subsequently, the rats in the D group were subdivided into two groups (n = 9), in which one group continued to receive a Zn-deficient diet, whereas the other received a Zn-supplemented diet (R; 48 mg Zn/kg diet) for 3 more weeks, after which the rats were sacrificed to collect their brain tissue. Markers of endoplasmic reticulum stress, ubiquitin-proteasome system, autophagy, and apoptosis, along with neurotrophic factors, were investigated by immunoblotting. Proteasomal activity was analyzed by the spectrofluorometric method. The results showed an altered ubiquitin-proteasome system and autophagy components and increased gliosis, endoplasmic reticulum stress, and apoptosis markers in Zn-deficient rats compared with the control group. Zinc repletion for 3 weeks could partially restore these alterations, indicating a necessity for an extended duration of Zn supplementation. In conclusion, a decline in Zn concentrations below a critical threshold may trigger multiple pathways, leading to brain-cell apoptosis.

Maternal dietary zinc status alters offspring female mammary gland development and response to acute 7,12-dimethylbenzanthracene insult

ABSTRACT We evaluated the effects of prenatal and postnatal dietary zinc (Zn) deficiency or supplementation on mammary gland morphology and on acute response to 7,12-dimethylbenzanthracene (DMBA) in pubertal female rats. On gestational day 10 (GD 10), rat dams were allocated randomly into three experimental groups of 10: a Zn-adequate diet group (ZnA) fed 35 mg Zn/kg chow, a Zn-deficient diet group (ZnD) fed 3 mg ZN/kg chow and a Zn-supplemented diet group (ZnS) fed 180 mg Zn/kg chow. After weaning, female offspring were fed the same diet as their dams until postnatal day 53 (PND 53). All animals received a single 50 mg/kg dose of DMBA on PND 51 and were euthanized on PND 53. Female ZnD offspring exhibited significantly less weight gain compared to the ZnA group and reduced mammary gland development compared to the ZnD and ZnA groups. By PND 53, the Ki-67 labeling index in mammary gland epithelial cells was significantly greater for the ZnS group than for the ZnA and ZnD groups. Apoptosis and ER-α indices did not differ among groups. The ZnD group exhibited significantly increased lipid hydroperoxide (LOOH) levels and decreased catalase and glutathione peroxidase (GSH-Px) activity compared to the ZnA and ZnS groups. The ZnS group exhibited significantly reduced superoxide dismutase (SOD) activity compared to the ZnA and ZnS groups. We observed atypical ductal hyperplasia in the mammary gland of female ZnS group offspring compared to the ZnA and ZnD groups and decreased expression of the Api5 and Ercc1 genes related to apoptosis inhibition and DNA damage repair, respectively. Both the Zn-deficient and Zn-supplemented diet exerted adverse effects on offspring mammary gland morphology and acute response to DMBA.

Effects of supplemental zinc on growth, carcass characteristics, and liver abscess formation in steers with experimentally induced ruminal acidosis challenge.

The study's aim was to evaluate the effect of dietary Zn supplementation on steer performance, biomarkers of inflammation and metabolism, and liver abscess formation in response to a mild acidosis challenge. Forty-two steers (417 ± 3.99 kg; n = 6/pen) were housed in pens with bunks designed to measure individual dry matter intake (DMI) and fed one of two diets containing either 0 (CON; n = 18) or 90 mg Zn/kg from a Zn-amino acid complex (Zn-AA; n = 18; AvailaZn; Zinpro) for 109 d. Six additional steers were fed the CON diet and did not undergo the acidosis challenge (NON; n = 6). The acidosis challenge included restricting steers to 50% of the previous 7 d daily DMI on days 46 and 47, steers were individually provided 10% of DMI as cracked corn (as-fed) at 0800 h followed by ad libitum feed access 2 h post-grain consumption. Steer was the experimental unit, and two contrasts were constructed: NON vs. CON and CON vs. Zn-AA. Blood samples were collected on days 40, 48, 53, 69, 80, and 108 and analyzed as repeated measures. Final body weight and overall average daily gain (2.29, 2.30, and 2.31 ± 0.920 kg/d for CON, Zn-AA, and NON, respectively) were not different (P ≥ 0.74) between treatments. By design, DMI was greater (P < 0.01) for NON compared to CON on day 46 but was not different (P ≥ 0.41) for the rest of the experiment. While hot carcass weight (423, 428, and 424 ± 7.9 kg for CON, Zn-AA, and NON, respectively) and ribeye area were not different (P ≥ 0.53) due to treatment, marbling score tended (P = 0.06) to be greater in CON compared to Zn-AA. The 12th rib backfat thickness was greater (P = 0.05) in NON vs. CON steers. Liver abscess incidence tended to be greater (P = 0.12) in CON (24% abscesses) vs. Zn-AA (6% abscesses). NON had a greater incidence (P = 0.05; 50% abscesses) compared to CON. Overall, blood fibrinogen and leukocyte counts were not different between treatments (P ≥ 0.67); however, neutrophil-to-lymphocyte ratio tended to be greater in NON vs. CON (P = 0.08). Serum aspartate aminotransferase and gamma-glutamyl transferase concentrations were greater in NON vs. CON (P ≤ 0.02), and serum alkaline phosphatase concentration was lesser in CON vs. Zn-AA (P < 0.01). Overall, dietary Zn supplementation tended to lessen incidence of liver abscesses with limited impacts on overall cattle performance. Shifts in liver enzymes may represent opportunities to identify cattle with liver abscesses earlier in the feeding period.

Litter quality and incidence and severity of footpad dermatitis in heat stressed broiler chickens fed supplemental zinc

In this study, we evaluated the effect of dietary Zn supplementation on growth performance, serum Zn concentration, litter quality attributes, and occurrence of footpad dermatitis in broiler chickens subjected to chronic heat stress. The study was conducted using a 2 × 2 factorial arrangement of dietary Zn oxide supplementation (0 and 70 mg/kg) and temperature (thermoneutral and chronic heat stress) in a completely randomized design. Five hundred forty-four 1-d-old male broiler chickens were randomly assigned to 4 experimental treatments with 8 replicate pens per treatment having 17 chickens in each replicate pen. Broiler chickens were fed corn-soybean meal-based basal diets for starter (0 to 10 d), grower (10 to 24 d), and finisher (24 to 42 d) growth periods with or without 70 mg/kg supplemental Zn oxide. Growth performance was recorded in terms of body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR). Serum Zn concentration and occurrence of footpad dermatitis were evaluated at d 14, d 28, and d 42 of experiment. Litter quality attributes were measured at d 1 and d 42 of the experiment except ammonia volatilization that was measured at d 28 and d 42 of the experiment. There was no interaction between dietary Zn and temperature for growth performance, serum Zn concentration, litter quality, and occurrence of FPD. Dietary Zn supplementation had no effect on overall growth performance, serum Zn, and litter quality of broiler chickens. However, supplemental Zn reduced the occurrence of footpad dermatitis in broiler chickens at the end of experiment (P < 0.05). Broiler chickens subjected to heat stress had lower overall BWG (P = 0.002) and FI (P = 0.001). Serum Zn concentrations were similar regardless of the temperature. Chronic heat stress increased the litter pH (P = 0.001), moisture (P < 0.001), temperature (P < 0.001) at d 42, and ammonia volatilization at d 28 (P < 0.001) and d 42 (P < 0.001). Incidence and severity of footpad dermatitis was greater in broiler chickens subjected to chronic heat stress (P < 0.01). Findings of our study indicate that heat stress results in poor growth performance and increases the incidence and severity of footpad dermatitis by lowering the litter quality in broiler chickens. In addition, dietary Zn supplementation may lower the occurrence of footpad dermatitis in broiler chickens without affecting the growth performance, serum Zn, and litter quality.

Impact of Maternal and Offspring Dietary Zn Supplementation on Growth Performance and Antioxidant and Immune Function of Offspring Broilers.

The current study investigated the effects of the maternal Zn source in conjunction with their offspring's dietary Zn supplementation on the growth performance, antioxidant status, Zn concentration, and immune function of the offspring. It also explored whether there is an interaction between maternal Zn and their offspring's dietary Zn. One-day-old Lingnan Yellow-feathered broilers (n = 800) were completely randomized (n = 4) between two maternal dietary supplemental Zn sources [maternal Zn-Gly (oZn) vs. maternal ZnSO4 (iZn)] × two offspring dietary supplemental Zn doses [Zn-unsupplemented control diet (CON), the control diet + 80 mg of Zn/kg of diet as ZnSO4]. oZn increased progeny ADG and decreased offspring mortality across all periods, especially during the late periods (p &lt; 0.05). The offspring diet supplemented with Zn significantly improved ADG and decreased offspring mortality over the whole period compared with the CON group (p &lt; 0.05). There were significant interactions between the maternal Zn source and offspring dietary Zn with regards to progeny mortality during the late phase and across all phases as a whole (p &lt; 0.05). Compared with the iZn group, the oZn treatment significantly increased progeny liver and serum Zn concentrations; antioxidant capacity in the liver, muscle, and serum; and the IgM concentration in serum; while also decreasing progeny serum IL-1 and TNF-α cytokine secretions (p &lt; 0.05). Similar results were observed when the offspring diet was supplemented with Zn compared with the CON group; moreover, adding Zn to the offspring diet alleviated progeny stress by decreasing corticosterone levels in the serum when compared to the CON group (p &lt; 0.05). In conclusion, maternal Zn-Gly supplementation increased progeny performance and decreased progeny mortality and stress by increasing progeny Zn concentration, antioxidant capacity, and immune function compared with the same Zn levels from ZnSO4. Simultaneously, Zn supplementation in the progeny's diet is necessary for the growth of broilers.

22 Young Scholar Talk PHD: Investigating Ovine Mastitis: Microbial Sources and Management Methods to Reduce the Prevalence

Abstract Subclinical mastitis, a common intramammary disease in sheep production, can be costly to producers due to compromised performance and decreased longevity. Our research focused on preventative and therapeutic measures on mammary health where the objectives were to identify (1) the impact of Zn supplementation on the milk microbiome and (2) the impact of management practices at lambing and weaning on prevalence and cure rate of subclinical mastitis, the milk microbiome, and levels of antimicrobial resistance in milk bacteria. In study 1, the milk microbiome was characterized during the first 3 wk of lactation and at weaning in ewes divergent in dietary Zn supplementation (1× = CON or 3× recommendations = ZnTRT). Mammary health was assessed using somatic cell count (SCC) class. Amplicon sequencing revealed the presence of Staphylococcus, Mannheimia, Corynebacterium, and Pseudomonas, all major mastitis pathogens. Effects of breed, dietary Zn concentration, and SCC class on diversity were limited to early lactation, where CON milk had greater composition stability than ZnTRT milk (P = 0.02). In study 2, milk bacteria were characterized by culture; Staphylococcus spp. and Streptococcus spp. were tested for antimicrobial susceptibility. Subclinical mastitis prevalence ranged from 22–66% where coagulase-negative staphylococci (CoNS; 59%), bacilli (35%), Mannheimia haemolytica (10%), S. aureus (8%), streptococci (5%), and Corynebacterium spp. (5%) were common. Milk samples were compared by jug bedding treatment: jugs were cleaned and dried with barn lime before adding fresh straw (CLEAN) or fresh straw was added atop soiled bedding (SOILED). Bedding had no effect on subclinical mastitis (P = 0.57), but CoNS had greater sulfadimethoxine resistance in SOILED isolates (P = 0.03). Additional mastitis control methods at weaning were evaluated: penicillin injection (PENN), restricted feed access (FAST), or their combination (COMBO). Weaning treatment did not affect cure rate from weaning to 3-d post- weaning (P = 0.21). Further characterization of these samples via microbial sequencing are underway with source tracking analyses to investigate an exogenous route via retrograde transfer and environmental bacteria or endogenous route via an entero-mammary pathway. Results support that breed, animal husbandry, and mammary health variably affect the milk microbiome and provide novel insight to the impact of management practices in a milk microbiome longitudinal study.

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) = 0.34g/bird/day; 95% confidence interval (CI) 0.27, 0.42)] and ADG (SMD = 0.43g/bird/day; 95% CI 0.35, 0.50) in broiler chickens in comparison with the controls. Dietary Zn supplementation improves FCR (SMD = - 0.16g/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.

Dietary Zinc supplementation impact on relative frequency and innate function of peripheral bovine immune cells

Abstract Zinc (Zn) is an essential micronutrient which is critical for optimum innate and adaptive immune function. While Zn deficiency leads to reduced growth and feed intake, the impact of Zn deficiency and supplementation on immune responses in beef cattle has not been properly addressed. To investigate to impact of dietary Zn supplementation on peripheral immune responses of growing cattle, 27 Angus crossbred steers were stratified by body weight and randomly assigned to three dietary treatments groups: 1) CON, no supplemental Zn, 2) Zn100, 100ppm of Zn or 3) Zn150, 150ppm of Zn delivered in premixes in total mixed rations. Whole blood obtained at 14 (D14) and 58 (D58) days after the start of the treatments was plated and stimulated with TLR agonists LPS (TLR4), PAM3CSK4 (TLR2/1), and Poly-I:C+Imiquimod (TLR3/7) for 48 h, then pro-inflammatory cytokine secretion was measured by ELISA on the supernatants. Additionally, whole blood was stained with surface antibodies to determine relative frequency of peripheral immune cell populations. We observed diminished IL-1ß secretion in response to Poly-I:C+Imiquimod in the CON group when compared to Zn150 (p=0.09) and Zn100 group (p=0.013) at D14 and D58, respectively. We observed no differences in IL-6 secretion upon TLR agonist stimulation between groups at any time point. Further, although no significant changes in CD4+, CD8+, TCRδ+ T cells, or CD21+MHCII+ B cells were observed, CD5+MHCII+ B cells had a higher relative frequency in the CON group when compared to Zn100 (p 0.03) and Zn150 (p 0.10) groups at D58. Future studies will address how Zn supplementation impacts the immune response to infection and disease susceptibility. This project was supported by Agriculture and Food Research Initiative Competitive Grant no. 2020-06540 from the USDA National Institute of Food and Agriculture

Activation of the zinc-sensing receptor GPR39 promotes T-cell reconstitution after hematopoietic cell transplant in mice

AbstractProlonged lymphopenia represents a major clinical problem after cytoreductive therapies such as chemotherapy and the conditioning required for hematopoietic stem cell transplant (HCT), contributing to the risk of infections and malignant relapse. Restoration of T-cell immunity depends on tissue regeneration in the thymus, the primary site of T-cell development, although the capacity of the thymus to repair itself diminishes over its lifespan. However, although boosting thymic function and T-cell reconstitution is of considerable clinical importance, there are currently no approved therapies for treating lymphopenia. Here we found that zinc (Zn) is critically important for both normal T-cell development and repair after acute damage. Accumulated Zn in thymocytes during development was released into the extracellular milieu after HCT conditioning, where it triggered regeneration by stimulating endothelial cell production of BMP4 via the cell surface receptor GPR39. Dietary supplementation of Zn was sufficient to promote thymic function in a mouse model of allogeneic HCT, including enhancing the number of recent thymic emigrants in circulation although direct targeting of GPR39 with a small molecule agonist enhanced thymic function without the need for prior Zn accumulation in thymocytes. Together, these findings not only define an important pathway underlying tissue regeneration but also offer an innovative preclinical approach to treat lymphopenia in HCT recipients.

Effects of In Ovo Injection of Zinc or Diet Supplementation of Zinc on Performance, Serum Biochemical Profiles, and Meat Quality in Broilers.

Simple SummaryZinc (Zn) is known as an essential trace mineral that plays a key role in metabolic processes such as synthesis, stability, and catalytic activity of many proteins in broilers. In ovo technology provides an alternative for delivering nutrient compounds to the embryo prior to hatching by injecting small amounts of material into a broiler egg during hatching. In this study, the in ovo injection of Zn and dietary supplementation of Zn were evaluated on their effects on growth performance, serum biochemical profiles, and meat quality in broilers. In ovo injection and Zn supplementation (i.e., 200 mg/kg) increased (p < 0.05) body weight and immunoglobulin G (IgG) compared to broilers fed with the control diet. In ovo injection group decreased (p < 0.05) feed conversion ratios compared to broilers fed with the no injection group. Our results indicated that broilers fed with a diet supplemented with 200 mg/kg of Zn could ameliorate growth performance, immune responses, and increase the unsaturated fatty acids of breast meat. The findings of this result highlighted that the diet supplemented with Zn has the effect to improve performance, blood immune response, and fatty acid profile of breast meat.This study investigated the main effects of the in ovo injection of inorganic zinc (Zn) or diet supplementation of Zn on performance, serum biochemical profiles, and breast meat quality in broilers. A total of 480 one-day-old broilers (Ross 308) were randomly divided into four groups: the control (Con, noninjected and basal diet), in ovo (injected 60 mg Zn/egg at 18 embryonic days of incubation and basal diet), Zn100 (noninjected and basal diet with Zn (100 mg/kg) for 35 days), and Zn200 (noninjected and basal diet with Zn (200 mg/kg) for 35 days) groups. The dietary supplementation of Zn increased feed intake (2860.42–2861.08 g), weight (1975.06–1985.25 g), and weight gain (1936.36–1946.53 g) compared to Con (2785.74, 1891.38, and 1852.62 g, respectively) after five weeks of age. No significant difference was found in biochemical parameters and leukocyte and erythrocyte levels in the blood among the four different groups. In ovo injected or supplemental Zn (100 and 200 mg/kg) increased IgG in the blood of broilers. Zn200 increased polyunsaturated fatty acids, and saturated fatty acid contents were reduced in breast meat compared with Con. In conclusion, Zn supplementation at 200 mg/kg could improve the weight, feed intake, blood immune response, and fatty acid profile of breast meat.

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.

Comparative effect of zinc supplementation by hydroxy and inorganic sources on nutrient utilisation, mineral balance, growth performance and growth biomarkers in pre-ruminant calves

ABSTRACT Zinc (Zn), an important microelement in ruminant diet, plays a critical role in various enzymes, hormones and functional proteins involved in nutrient metabolism. The present study was conducted to assess the effect of zinc hydroxychloride (Zn5(OH)8Cl2·H2O [ZnOHCl] and zinc sulphate (ZnSO4) on nutrient utilisation, mineral metabolism and biomarkers pertaining to growth performance in pre-ruminant crossbred calves. Twenty-four crossbred calves [body weight (BW); 31.03 ± 4.30 kg; age 10 d] were randomly allocated to four treatment groups (n = 6), i.e. no supplementation of Zn (0 mg/kg dry matter [DM]), 80 mg/kg DM Zn as ZnSO4(ZnS-80), 40 mg/kg DM Zn as ZnOHCl (ZnH-40) and 80 mg/kg DM Zn as ZnOHCl (ZnH-80) for 90 d experimental period. Results showed that dietary Zn supplementation improved (p < 0.05) feed intake, BW, average daily gain, heart girth, body length, plasma growth hormone, insulin-like growth factor and thyroxin concentration; however, nutrient digestibility remained unaffected among the groups. Addition of Zn increased (p < 0.05) Zn retention and plasma Zn concentration without affecting retention and plasma concentration of other minerals. Retention of Zn was the highest in ZnH-80 group followed by ZnH-40, ZnS-80 and lowest in control group. Overall results of the present study indicate that regardless of sources and levels, Zn supplementation increased growth performance, plasma Zn concentration and hormones levels in pre-ruminant crossbred calves. However, supplementation of hydroxy Zn at 40 mg/kg DM had similar effect as produced by ZnSO4 or ZnOHCl at a supplementation level of 80 mg/kg DM. Therefore, from the present study it can be concluded that ZnOHCl can be used as a Zn source for pre-ruminant calves at a lower dose compared to ZnSO4.

Dietary zinc supplementation affects eggshell quality and ultrastructure in commercial laying ducks by influencing calcium metabolism

This study evaluated dietary Zn supplementation on productive performance, eggshell quality and ultrastructure, and calcium metabolism during eggshell formation in laying ducks. A total of 360 Longyan laying ducks (45-wk) were randomly divided into 5 treatment groups with 6 replicates of 12 birds each and fed for 20 wk. The 6 treatments fed the basal diet supplemented with 0 (control), 20, 40, 80, or 160 mg Zn/kg (ZnSO4·H2O). Dietary supplemental level at 80 mg/kg increased egg production (4.3%) and mass (5.7%), and decreased FCR (2.9%) compared to the basal diet, and these indices increased quadratically with increasing Zn supplemental levels (P < 0.05). The shell breaking strength (15.8%) and fracture toughness (10.6%) were higher with the supplementation of Zn at 80 mg/kg than the basal diet, and increased quadratically with Zn supplementation (P < 0.05). Dietary supplementation of Zn at 80 mg/kg improved shell ultrastructure by increasing total (9.0%) and effective thickness (14.2%) and decreasing mammillary thickness (12.0%), and their responses were quadratic with increasing Zn levels (P < 0.05). The supplementation of Zn affected the calcium contents in plasma, tibias and ulna, ulna phosphorus content, and linear and quadratic effects were observed, and higher values were observed with 160 mg/kg Zn supplementation than control (P < 0.05). The supplemental Zn level at 80 mg/kg increased shell effective thickness in growth stage (P < 0.05), and shell calcium and phosphorus content in initial and growth stages (P < 0.05). Dietary Zn supplementation did not affect the gene expression of Ca2+ transporters in the eggshell gland, but affected the expression of HCO3− exchanger in initial and growth stage (P < 0.05). Overall, dietary Zn supplementation could improve productive performance and shell quality in laying ducks at late phase of production, and calcium metabolism and deposition were modulated by Zn influencing HCO3− secretion and thus affecting shell ultrastructure and quality. A supplemental level of 80 mg/kg Zn in the diet with a basal content of 34.0 mg/kg was optimal, and higher level (160 mg/kg) decreased shell calcium deposition by depressing its metabolism.