Exposure to trace elements of flamingos living in a biosphere reserve, the Camargue (France)

AIMS: To determine the variability of concentrations of Zn in feed, when used as a supplement to prevent facial eczema, and to determine the variability in concentrations of Zn in serum between cows and herds that are being supplemented with ZnO in feed, using in-shed feeders or on a feed pad.METHODS: Sixteen commercial dairy farms in the Waikato region of New Zealand were enrolled, that were supplementing cows with ZnO in the feed using either an automatic in-shed feeder (ASF) or a feed pad (FP) using a feed-out or mixer wagon. On each farm 10 cows were selected by the farmer, that were assumed to be representative of the age and liveweight of the herd. Four hours after supplement feeding, each cow was weighed and a blood sample collected for measurement of concentrations of Zn in serum. Three samples of feed were collected from each farm for Zn analysis, from the beginning, middle and end of the feed being distributed. Levene’s test for homoscedasticity was used to analyse whether there were differences in variation of individual concentrations of Zn in serum, and in the feed, between the two feeding systems. Multivariable linear regression was used to examine associations between age, feeding method or liveweight and concentrations of Zn in serum, after accounting for the variability between farms.RESULTS: Of the 163 cows sampled, concentrations of Zn in serum were between 20–35 µmol/L in 75/163 (46 (95% CI=38–54)%) cows; were <20 µmol/L in 71/163 (44 (95% CI=36–52)%) cows, and >35 µmol/L in 17/163 (10 (95% CI=6–16)%) cows. The variation in concentrations of Zn in serum in individual cows differed between farms (p<0.001), and the variability was greater for cows fed using a FP than ASF (p<0.001). There was no difference in the variation of concentrations of Zn in feed between the two feeding methods (p=0.54), but concentrations of Zn in serum were associated with the amount of Zn offered in feed (p=0.008).CONCLUSIONS AND CLINICIAL RELEVENCE: There was significant variability between farms in the concentrations of Zn in the serum of cows being supplemented with ZnO in feed. Only 46% of cows sampled had concentrations of Zn between 20–35 µmol/L. Effective management of facial eczema should include monitoring Zn in the feed and in serum to ensure cows are receiving the correct dose they require.

Aims: To evaluate agreement between the concentration of Zn in serum from samples collected from cattle and sheep into standard collection tubes for serum and from samples collected into tubes developed for trace element measurement. Methods: Eighty-eight animals (78 cattle and 10 sheep) on eight farms had paired blood samples collected into standard serum and trace element vacutainers. The paired samples were submitted the same day to the laboratory to be tested for the concentration of Zn in serum using atomic absorption spectrophotometry. The agreement between the paired results was then assessed using limits of agreement analysis. On one farm an additional 10 pairs of samples was taken from the same animals; this second set of paired samples was refrigerated for 48 hours prior to laboratory submission to identify the impact of delaying submission on the apparent concentration of Zn in serum. Results: The limits of agreement analysis found no evidence of a systematic difference between Zn concentrations in serum collected into standard serum tubes and into trace element tubes as neither the intercept nor the slope on the mean-difference plot were significantly different from zero. The SD of the difference between results increased as the concentration of Zn increased, so at the lowest Zn concentration reported in this study (6.9 μmol/L) the limits of agreement were ±1.07 μmol/L, while at the highest (23.5 μmol/L) they were ±3.39 μmol/L. Refrigerating the sample (as whole blood) for 48 hours prior to submission increased the apparent concentration of Zn in serum in both standard serum tubes and trace element tubes by 1.3 μmol/L (95% CI = 0.75–1.85). Conclusions: There was no evidence that the concentration of Zn in serum from standard serum tubes were artificially elevated. In contrast, delaying sample submission by 48 hours did elevate Zn concentrations. Clinical relevance: While these data apply only to the batch of vacutainers used in this study, there is unlikely to be much between batch variation in the potential for contamination. Thus these results suggest that monitoring zinc status in ruminants, by measuring the concentration of Zn in serum from samples collected into standard serum tubes does not result in clinically relevant alterations in Zn concentration compared to using specific trace element tubes. However delaying submission to the laboratory may result in significantly elevated concentrations of Zn in serum so should be avoided.

ABSTRACTAimsTo examine the relationship in dairy cattle between serum and faecal Zn concentrations and daily intake of Zn supplemented with an oral drench; and whether total daily intake (TDI) of Zn in dairy cattle can be predicted from single measurements of Zn concentration in serum or faeces.MethodsA convenience sample of 20 animals from three stock classes (lactating cows, dry cows, heifers), that had not received Zn supplementation in the previous 60 days, was enrolled in the study. From Days −7 to −1, animals received no Zn supplementation. On Day 0, 15 animals per class were assigned daily drenching with increasing doses of ZnSO4.7H2O while five remained controls. From Days 0–6, treatment animals received 12.5 mg/kg LWT of Zn/day; from Days 7–13, 25 mg/kg LWT Zn/day and from Days 14–20, 37.5 mg/kg LWT Zn/day. Animals co-grazed within each stock class. Pasture, serum and faecal samples were collected at the start and at weekly intervals before each increase in Zn supplementation. Mixed and non-parametric models were used to assess treatment effects and whether daily intake of Zn could be predicted from Zn concentrations in serum and faeces.ResultsDosing with 0, 12.5, 25.0 and 37.5 mg Zn/kg LWT resulted in serum Zn concentrations of 12.1, 16.7, 27.2 and 35.8 µmol/L in heifers, 13.3, 17.1, 26.4 and 40.0 µmol/L in dry and 11.9, 12.1, 23.4 and 27.2 µmol/L in lactating cows. Dosing with the same amounts of Zn resulted in faecal Zn concentrations of 2.95, 21.72, 40.32 and 53.27 mmol/kg DM in heifers, 2.81, 23.77, 55.16 and 68.20 mmol/kg DM in dry and 3.00, 12.71, 34.86 and 57.53 mmol/kg DM in lactating cows, respectively. Treatment elevated serum and faecal Zn concentrations above controls (p < 0.001). Supplemented lactating cows had lower serum Zn concentrations than dry cows or heifers (p < 0.01). Supplemented dry cows had faecal DM Zn concentrations higher than heifers or lactating cows (p < 0.05). Analysis showed serum and faecal Zn concentrations could predict TDI of Zn (p < 0.001). Concentrations of Zn in faeces estimated TDI of Zn within a narrower predictive interval than serum Zn concentrations.Conclusions and clinical relevanceConcentrations of Zn in serum and faeces were positively associated with TDI of Zn in dairy cattle and could predict TDI of Zn. When using serum and faecal Zn concentrations to estimate TDI Zn, stock class must be accounted for.

AIM: To investigate the efficacy of intra-ruminal Zn boluses as aids in providing protection from natural Pithomyces chartarum challenge in sheep. METHODS: Seventy-two adult sheep (mean weight 59 (SEM 0.5) kg) were divided into four groups. Commencing on Day 0, they received either a proprietary bolus containing 67 g ZnO (equivalent to 54 g Zn) (ZnO group), two different levels of elemental Zn (81 and 108 g) delivered in boluses each containing 27 g Zn (Zn81 and Zn108 groups, respectively), or remained untreated (control). Concentrations of Zn in serum, activities of gamma-glutamyl transferase (GGT) in serum, and spore counts on pasture were measured weekly from Day -6, and concentrations of Zn in faeces weekly from Day 21, until Day 77. RESULTS: Mean concentrations of Zn in serum between Days 14 and 42 were significantly higher in ZnO animals (15.4 (SEM 0.70)µmol/L) than the other groups. Mean concentrations in Zn108animals (11.1 (SEM 0.26) µmol/L) were significantly higher than controls, but there were no differences between Zn81 and the controls (9.9 (SEM 0.20) and 9.4 (SEM 0.26) µmol/L, respectively). Between Days 21 and 49, there was no significant difference in mean concentrations of Zn in faeces between ZnO and Zn81 animals (307 (SEM 28) and 281 (SEM 29) mg/kg fresh weight (FW), respectively), but concentrations were significantly higher in Zn108 animals (500 (SEM 40) mg/ kg FW). Spore counts exceeded 70,000/g on Days 14, 28, 49, 56 and 63 but there were no clinical signs of facial eczema. In controls, activities of GGT were unchanged until Day 21, then increased to 637 IU/L at Day 70; for ZnO animals, activities remained <75 IU/L until Day 14, then increased to 200 IU/L at Day 70; for Zn81 and Zn108, they remained <75 IU/L until Day 35, and then increased at Day 70 to 369 IU/L and 293 IU/L, respectively. From Day 56 activities were significantly lower in all treated groups compared with controls, but there was no significant difference between the three Zn bolus treatments. There were significant negative correlations between activities of GGT and concentrations of Zn in serum in Zn108 animals, and with concentrations of Zn in faeces for both Zn81 and Zn108 groups. CONCLUSION: Elemental Zn boluses can reduce activities of GGT associated with elevated spore counts. The association between concentrations of Zn in faeces and activities of GGT suggests that a minimum concentration of Zn in the gastrointestinal tract may be important in providing protection against sporidesmin.

Zinc (Zn) and magnesium (Mg) are essential trace elements in humans. Their deficiency may be associated with inflammation and oxidative stress (OS) in patients with diabetic nephropathy (DN), but the mechanisms involved have not been fully characterized. We aimed to investigate the relationships between circulating concentrations of Zn and Mg and pro-inflammatory factors with DN-associated renal functional damage in patients with type 2 diabetes mellitus (T2DM). To this end, we studied 20 healthy people, 24 patients with T2DM, and 59 patients with T2DM and T2DN. Serum and urine Zn and Mg concentrations were measured using the 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamine) phenol (nitro-PAPS) chromogenic method and the xylidyl blue method, respectively, and the circulating concentrations of pro-inflammatory cytokines [interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12, and tumor necrosis factor-α (TNF-α)] were measured using flow cytometry. The serum concentrations of Zn and Mg were significantly lower in patients with T2DM and DN than in healthy controls. Serum Zn, urine Zn, and urine Mg concentrations decreased, while those of IL-6 and IL-8 increased with the progression of DN-associated renal functional damage. Furthermore, the serum and urine Zn concentrations negatively correlated with the serum IL-6 and IL-8 concentrations. Notably, the serum Zn concentration was found to independently protect against DN in patients with T2DM. Hypozincemia may be associated with the T2DN-associated renal functional damage because it exacerbates inflammation.

AIMS: To describe and evaluate the current practices used to manage and prevent facial eczema (FE) in North Island dairy herds, and determine the within-herd prevalence of cows with elevated activities of gamma glutamyl transferase (GGT), and with concentrations of Zn in serum <18 μmol/L.METHODS: Between January and May 2014, 105 herd managers from throughout the North Island of New Zealand were invited to participate in the study when regional spore counts for Pithomyces chartarum started to rise towards 30,000 spores/g pasture. Managers selected 10 representative cattle that were weighed and blood-sampled by the herd veterinarian. Blood samples were analysed for concentrations of Zn in serum and GGT activity. Pasture samples were also collected and submitted for spore count estimation. Finally a survey of farm management practices relating to prevention of FE was completed by the herd manager. A mixed-effects logistic regression model was used to determine associations between herd-level and cow-level explanatory variables and the probability of a cow having a concentration of Zn in serum <18 µmol/L.RESULTS: Of the 1,071 cows tested, 79 (7.3 (95% CI=5.8–9.0)%) had GGT activity in serum >300 IU/L, and 35/106 (33 (95% CI=24.2–42.8)%) herds had ≥1 of the 10 cows sampled with GGT activity >300 IU/L. Of the 911 cows that were being treated with Zn, concentrations of Zn were between 18–35 μmol/L in 398 (43.6 (95% CI=40.4–46.9)%) cows, were >35 μmol/L in 32 (3.5 (95% CI=2.4–4.1)%) cows, and <18 μmol/L in 479 (52.6 (95% CI=49.3–55.9)%) cows. After adjusting for the confounding effect of region, the odds of a cow having concentrations of Zn in serum <18 μmol/L were 5.5 (95% CI=1.1–29) times greater for cows supplemented with zinc in water compared with those supplemented by drenching. Of the 105 herd managers, 103 (98%) stated that they had access to regional spore count data, but only 35/105 (33%) reported that they measured spore counts on their own farm. Overall, 98/105 (93%) managers reported that they had some form of FE management programme in place. Fungicides were used on their own or in combination with zinc treatments in 10 herds, ZnSO4 in water troughs was used in 68 herds, oral drenching with ZnO in nine herds, and ZnO supplied in-feed in 26 herds. Estimated daily dose rates of zinc were less than that required to treat a 400 kg cow on 42/68 farms that administered ZnSO4 in the water or ZnO as a drench.CONCLUSION AND CLINICAL RELEVANCE: This study has shown that FE management on dairy farms in the North Island of New Zealand could be substantially improved. It is likely that improved FE management would occur if herd managers were provided with more feedback on the success (or otherwise) of their FE management programmes.

Serum copper and zinc concentrations in a representative sample of the Canarian population

Automobile technicians in resource-poor settings often work in poor environments and are exposed to chemicals that put them at risk of ill health and disease. These chemical exposures could affect blood coagulation, leading to bleeding disorders or thrombosis. The present study is aimed at assessing prothrombin test (PT) and activated partial thromboplastin test (aPTT) values, serum zinc (Zn) and copper (Cu) concentrations, and blood lead level (BLL) among occupationally exposed automobile technicians compared to unexposed controls. A total of 140 consenting participants comprising 70 automobile technicians and 70 unexposed controls were recruited for this case-control study. A 6-mL blood sample was drawn from each participant for estimation of BLL, serum Zn and Cu concentrations, and PT and aPTT values. Blood lead level, and serum Zn and Cu concentrations were determined using atomic absorption spectrophotometry, while PT and aPTT values were determined using Innovin PT and Actin FS Activated PTT reagents on the Sysmex CA-101 coagulation analyser. Data were analysed using t-tests, chi-square tests, and logistic and multiple linear regression analyses with statistical significance set at p < 0.05. The mean BLL, serum Zn concentration, and PT and aPTT values were significantly higher in automobile technicians compared to controls. Binary logistic regression showed that automobile technicians had higher odds of elevated PT value (OR = 21.769; p = 0.000), aPTT value (OR = 1.348; p = 0.018), BLL (OR = 1.261; p = 0.000) and serum Zn concentration (OR = 1.063; p = 0.005) than unexposed controls. Linear regression showed significant positive association of PT value with BLL and with serum Zn concentration. Higher PT and aPTT values reflect prolonged blood coagulation time among automobile technicians, which indicates impairment of extrinsic and intrinsic coagulation pathways associated with work-related exposures.

The iron nutrition status influences other micro‐mineral status through interacting in the intestinal absorption or in the uptake into tissue. The iron‐deficiencies of women are usually not a kind of an anemia, but a state of only iron storage depletion without anemia. Extracellular mineral concentrations can be changed by exercise through water and electrolyte loss of sweat. We compared the minerals levels in serum according to body iron stores and physical activity in young women. We collected bloods of young collegiate sedentary women and physically active athletic women, and serum concentrations of Na, Cl, Ca, Fe, Zn, Se were measured by neutron activation analysis method. The proportion of females with iron depletion(ID, serum ferritin &lt;20μg/L) were 50% in sedentary and athletic women, respectively. The subjects were divided into 4 groups according to physical activity and iron storage. The serum Na, Cl and Ca level showed increasing tendencies in sedentary with normal iron status compared to the athletes with ID, although no significant differences among 4 groups. The serum Fe levels did not show significant differences among 4 groups, although lower values in the athletes than sedentary women. The serum Zn and Se concentrations were the highest in athletes with normal iron status and the lowest in sedentary with ID. In conclusion, this study suggests that the serum Se and Zn concentrations in young women might be influenced by the chronic physical activity and iron status. This study was supported by the MOST of Korea

Trace elements play an important role in metabolism. We compared the daily intake and serum concentrations of copper (Cu), selenium (Se), and zinc (Zn) across a spectrum of glucose tolerance status in a representative U.S. population. Daily intake and serum concentrations of Cu, Zn and Se in 5087 adults from the 2011–2016 National Health and Nutrition Examination Survey (NHANES) were examined and compared to normal (NGT) and abnormal (AGT) glucose tolerance and the presence of diabetes mellitus (DM). Other than Zn deficiency (21.15%), the prevalence of Zn, Se, and Cu excess and Se and Cu deficiency were low (<4.00%). As compared to the NGT group, Cu and Se supplementation was higher in the AGT and DM groups (p < 0.0001 for all). Serum Se and Zn, but not Cu, concentrations were highly correlated with daily intake (p < 0.0001 for both). As compared to the NGT group, serum Cu concentration was highest in the AGT group (p = 0.03), serum Se concentration was highest in the DM group (p < 0.0001), and serum Zn concentration was highest in the AGT group (p < 0.0001). Serum Se and Zn concentration was correlated with daily Se and Zn intake. Even within the reference range for serum Cu, Se, and Zn concentrations, a higher serum concentration of Cu, Se, and Zn was associated with abnormal glucose metabolism. Although the casual relationship remains to be elucidated, these data suggest caution in Cu, Se and Zn supplementation in non-deficient individuals.

Aims To describe the concentration of Zn in bulk tank milk (BTM) in a sample of New Zealand dairy farms, investigate the association between the method of Zn administration for facial eczema prophylaxis and Zn concentrations in BTM and investigate the relationship between the concentration of Zn in serum and that in BTM. Methods Multiple BTM samples (n = 3,330) collected during milk pick-up by the milk tanker driver were stored and tested for 121 farms, in Northland (n = 50), Waikato (n = 51) and Southland (n = 20) from February to May 2017. Enrolled farms provided retrospective information on the type of Zn supplementation (if any) used for the prevention of facial eczema and the timeframe over which supplementation occurred. In addition, the concentration of Zn in serum was measured in blood samples collected from ≥15 cattle per farm for 22 farms from Northland (n = 11) and Waikato (n = 11), and compared against the concentrations of Zn in BTM on the day of blood sampling. A linear mixed model was used to model log Zn concentrations in BTM using method of Zn supplementation, region, milk fat and protein percentage, volume of milk, and frequency of milk pick-up as risk factors. A mixed logistic regression model was used to assess the relationship between Zn concentrations in BTM and the presence of cows with a concentration of Zn in serum of ≥20 µmol/L. Results The median Zn concentration in BTM was 67.9 (min 38.9, max 146.6) µmol/L. The median range of Zn concentrations for repeated samples of BTM within farm was 22.6 µmol/L. In comparison to farms that did not use any form of Zn supplementation, farms that supplemented Zn through a slow-release capsule, oral drench, in feed or a combination of in-feed and water were associated with increased concentrations of Zn in BTM (p < 0.001). There was no difference in Zn concentrations in BTM between farms that administered Zn through the water only and farms that did not administer Zn (p = 0.22). Every 15.3 μmol/L increase in Zn concentration in BTM was associated with 2.2 times (95% CI=1.7–2.9) the odds of a cow having Zn concentration in serum ≥20 μmol/L. Conclusion and clinical relevance Zn concentration in BTM is highly variable between farms, days and Zn administration method. Zn concentration in BTM content has modest potential as a way to signal whether a herd has achieved the high Zn status considered to be protective against FE.

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.

The aim of this study was to evaluate different dietary level of Zinc (Zn) and Copper (Cu) supplementation according to European and non-European levels on the health and performance of pigs 14 d after weaning. A total of 120 piglets [initial body weight = 7.14 ± 0.92 kg] were divided into 4 experimental treatments: positive control (PC, 2,500 ppm of Zn, ZnO) and 3 treatments in which Zn and Cu were added through potentiated ZnO and Cu2O according to different European and non-European levels of inclusion: EU (120 ppm of Zn; 140 ppm of Cu), non-EU+ (300 ppm of Zn; 200 ppm of Cu) and non-EU- (300 ppm of Zn; 140 ppm of Cu). Growth performance, serum Zn and Cu concentrations, fecal score, blood biomarkers of intestinal integrity, and fecal microbial composition were examined and analyzed using GLM and MIXED procedures of SAS. Fecal samples at 14 d were collected and the V3–V4 hypervariable regions of the bacterial 16S gene were sequenced in one Illumina MiSeq run. Body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), feed conversion ratio (FCR) and (feed efficiency (FE) were not affected by the experimental treatments. The fecal score suggests that during the first 14d, the consistency of the feces tended (P &amp;lt; 0.10) to be less in the three treatment groups while in PC, the greatest concentration of Zn favored a better fecal consistency. The initial serum Zn and Cu concentrations were similar for all dietary treatment groups. After 14 d, serum Zn concentration was significantly greater in PC (15.71 ± 6.25 µg/L, P &amp;lt; 0.05). No differences were highlighted in serum Zn concentration among the other 3 treatment groups. Serum Cu concentrations revealed statistically significant results (P &amp;lt; 0.05) on 14 d after weaning in EU, non-EU+ and non-EU- groups, showing greater concentrations of Cu (17.65 ± 5.49 µmol/L, 17.73± 3.46 µmol/L 18.33 ± 4.13 µmol/L, respectively) compared with PC (11.87 ± 3.60 µmol/L). These results suggested that the EU level of inclusion of both potentiated Zn and monovalent Cu is enough to reach the same Cu and Zn plasma concentrations of non-EU treatments. Plasma DAO was negatively (P &amp;lt; 0.05) affected in non-EU-. Firmicutes and Bacteroidetes were the most abundant phyla in fecal microbiome. Non-EU- contributed to a significant decrease in biodiversity in fecal microbiota as depicted with Shannon for diversity and Simpson for evenness indexes (P &amp;lt; 0.05). In fecal samples, the presence of genera linked to a greater disruption of the gut barrier (Escherichia-Shigella) was depicted in non-EU- group, indicating significant modifications of the microbial community. These results suggest the need for a balanced supplementation of Cu and Zn through more bioavailable sources. The use of potentiated ZnO and Cu2O according to European levels could represent a valid strategy to enhance weanling piglets gut health and to reduce the environmental impact.

ABSTRACTAims: To monitor the effect of using long-acting Zn boluses on the Zn status of a group of South American camelids, using measurements of concentrations of Zn in faeces and serum.Methods: As part of a facial eczema (FE) prevention programme, 15 camelids were treated with long-acting Zn boluses designed for preventing FE in sheep. Based on bodyweight, 13 alpacas (Vicugna pacos) received two boluses (26.4 g Zn/bolus) and two llamas (Lama glama) received three boluses. In order to monitor Zn status, measurements were made of concentrations of Zn in serum and faeces immediately prior to bolus treatment (Week 0) and 4, 6, 8 and 10 weeks later. Gamma glutamyl transferase (GGT) activity in serum was measured at Weeks 0 and 8.Results: Two alpacas regurgitated the boluses; in one case the animal was quickly re-treated but this was not possible in the second animal. Mean concentrations of Zn in faeces were higher at all time points compared to Week 0 (p < 0.001). Peak concentrations were measured at Week 8, and concentrations >120 mg/kg fresh weight (FW), suggested as being protective in calves, were only measured in all (13/13) treated camelids at Week 6. Mean concentrations of Zn in serum differed between weeks of sampling but changes were not consistent, and concentrations did not exceed 18 μmol/L following treatment. There was no evidence of a natural sporidesmin challenge during the study period and activity of GGT in serum of all animals was <45 IU/L.Conclusions: Treatment with Zn boluses significantly increased concentrations of Zn in faeces but not in serum, but peak concentrations in faeces were only detected 8 weeks after treatment.Clinical Relevance: The delay in achieving concentrations of Zn in faeces which were associated with protection against FE in calves, combined with the difficulties of administering boluses to camelids, means that we do not believe that Zn boluses should be used as the primary method for preventing FE in camelids. We recommend that FE prevention in camelids should focus on minimising spore production in pasture through the use of fungicides, grazing management and alternative forages, with boluses only used when it is thought that these methods are unlikely to provide sufficient protection against FE. Such use should always be under the guidance of a veterinarian and monitoring of serum GGT activity should be used to ensure that FE control is being achieved.

Aims: To investigate the relationship between Zn concentrations in serum and those in milk or faeces, and to assess the ability of the Zn concentrations in milk, serum and faeces to predict intake of ZnO in dairy cattle. Method Seventy cows from one commercial farm in the Waikato region of New Zealand received one of seven dose rates (0, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 g/100 kg bodyweight (BW)) of ZnO given by oral drench, every morning, for 7 consecutive days. Every afternoon, milk and blood samples were collected from all cows. Free-catch faecal samples were collected during the afternoon milking on 3 days throughout the trial. Linear mixed models were used to assess the relationship between the concentration of Zn in serum and that in milk, and in faeces, respectively, and the relationship between dose rate of ZnO and concentrations of Zn in serum, faeces and milk, respectively. Receiver operating characteristic curve analysis was used to determine the ability of the Zn concentration in serum, milk and faeces to predict that a cow had been treated with a dose of ZnO ≥2.5 g/100 kg, the industry-recommended dose rate needed to protect against facial eczema. Results: A 1-µmol/L increase in Zn concentration in milk was associated with a 0.14 (95% CI=0.11–0.17) µmol/L increase in Zn concentration in serum. Zn concentration in faeces was scaled by its SD; a 1 SD increase was associated with a 1.83 (95% CI=0.54–3.12) µmol/L increase in zinc concentration in serum. Zn concentrations in serum and faeces increased with increasing dose rates of ZnO. No differences in Zn concentrations in milk were noted between animals dosed with 1.5–3.5 g ZnO/100 kg BW, inclusive. At the optimal threshold for Zn concentration in serum, 22 µmol/L, the sensitivity was 0.76 (95% CI=0.69–0.82) and specificity 0.85 (95% CI=0.80–0.89). For the concentration of Zn in faeces, the optimal threshold was defined as 17.36 mmol/kg, with a corresponding sensitivity of 0.84 (95% CI=0.84–0.85) and specificity of 0.85 (95% CI=0.73–0.94). At the optimal threshold for the Zn concentration in milk (76.6 µmol/L), the sensitivity was lower than the other two sample types at 0.59 (95% CI=0.52–0.67), but with a similar specificity of 0.84 (95% CI=0.79–0.88). Conclusions and clinical relevance: The concentration of Zn in milk shows promise as an initial screening test to identify dairy farms that do not provide adequate zinc to provide protection against FE.