Copper toxicity in a New Zealand dairy herd

Feeding nanoparticles of copper oxide coated with lysine with or without added antagonists affects the copper status but not performance of Holstein dairy cows

The apparent absorption of copper (Cu) in ruminants is low, with between 0.01 and 0.07 g/g absorbed from sources such as copper oxide (CuO) under typical feeding conditions, resulting in high levels of excretion. Improving the bioavailability of Cu could reduce the supplemental amount required to maintain Cu status and reduce excretion, particularly in the presence of dietary antagonists such as sulfur (S) and molybdenum (Mo). The objective of our study was to determine the Cu status of cows when fed nanoparticle CuO coated with Lys compared with conventional CuO when fed without or in combination with antagonists to Cu absorption (S and Mo) in the diet of dairy cows. Fifty-six multiparous Holstein-Friesian cows that were 48 d ± 17.4 (mean ± SD) post calving and yielding 40.6 ± 6.9 kg milk/d were used in a 2 × 2 factorial design. The 4 treatment groups were; CuO (O-), CuO with added antagonists (O+), nano CuO with a lysine coating (N-), and nano CuO with a Lys coating with added antagonists (N+), fed for 16 wks. We formulated the diets to contain approximately 17 mg Cu/kg dry matter (DM) and diets with antagonists contained an additional 1 g S/kg DM and 6 mg Mo/kg DM, with Lys added to O- and O+ to provide the same daily supply as N- and N+. Blood samples were collected at wk 0, 2, 4, 6, 10 and 16, and liver biopsy samples at wk 0 and 16. We found no effect of dietary treatment on DM intake, milk yield, live weight or body condition score, with mean values of 23.3 kg/d, 40.1 kg/d, 646 kg and 2.68, but milk SCC was higher in cows fed conventional compared with non CuO, or with added antagonist. We also found no effect of treatment on blood activity of gamma glutamyl transferase, superoxide dismutase or ceruloplasmin, hematology profile, or plasma Cu and iron concentration. We found that plasma Mo concentration was increased from 0.36 µmol/L in cows fed O- or N- to 0.80 µmol/L in those receiving O+ or N+. Additional dietary antagonists also decreased the concentration of Cu in the liver of cows fed conventional CuO (C+) over the study period by 1.3 mg/kg DM/d, but in cows fed dietary antagonists and nano CuO coated with Lys (N+), liver Cu concentration was increased by 1.1 mg/kg DM/d. Our study is the first to demonstrate that reducing the particle size of CuO into the nano scale with a lysine coating improves the bioavailability of CuO in the presence of dietary antagonists in dairy cattle, and we did not observe any negative effects on performance or health.

Trace Mineral Nutrition in Confinement Dairy Cattle

Veterinarians are often called upon to diagnose health-related issues on the farm that may be related to trace mineral deficiencies or toxicities. Trace mineral feeding rates are often not available due to the proprietary nature of the trace mineral premixes provided by nutritional consultants. The veterinarian needs to be aware of the common clinical signs of trace mineral deficiencies and toxicities, interactions between trace minerals that may result in deficiencies, clinical samples that are necessary for the proper diagnosis, and the recommended normal ranges of each trace mineral depending on the age of the animal.

Comparison of a novel form of zinc with zinc oxide bolus licensed for prevention of facial eczema, and interaction with copper oxide in sheep

To evaluate a novel elemental zinc bolus compared with a registered positive control zinc oxide bolus and assess serum zinc concentrations following concomitant treatment with a capsule containing copper oxide needles. Forty Romney-cross ewes were randomly allocated in a 2 × 2 factorial design study. On Day 0, 20 ewes received novel boluses containing elemental zinc (Investigational Veterinary Product, IVP) while 20 received a zinc oxide bolus (control; CP). Half the animals in each zinc treatment group (n = 10) were treated with a copper oxide needle capsule [Copasure® - Ewe]. Weekly, from Day -7 to 56, all ewes were assessed for signs of photosensitization, and for 10 ewes from each zinc treatment groups, samples were collected for analysis of serum GGT activity, serum zinc concentrations, faecal zinc concentrations and on Days -7 and 56, liver copper concentrations. Multivariable random-effects models assessed the effects of zinc treatment, copper treatment, treatment interactions and time on all analytes. Regression models examined associations between serum and faecal zinc concentrations and GGT activity. Low spore numbers indicated low Pithomyces chartarum challenge. Serum zinc levels were significantly higher in the IVP than in the CP group [p < 0.0001] and varied by time [p < 0.001] and positively associated with faecal zinc concentration [p < 0.001]. Copper treatment did not affect serum zinc [p = 0.82] or faecal zinc [p = 0.92] concentrations. Liver copper concentrations did not differ between zinc treatment groups on Day -7 [p = 0.6] or Day 56 [p = 0.95]. Only the CP/no copper group had no increase in liver copper concentrations.

Diagnosing subclinical facial eczema in cattle: does combining liver enzyme tests increase the accuracy of diagnosis?

AIMS

To assess whether adding glutamate dehydrogenase (GDH) activity measurements to measurements of gamma-glutamyl transferase (GGT) activity appreciably increases the accuracy of diagnosis of subclinical facial eczema (FE) in cattle.

METHODS

As part of a larger study on the impact of FE on productivity, GGT and GDH activities were measured in serum samples collected from 426 cattle from one dairy farm in the Taranaki region in April 2018. Bayesian latent class analysis was then used to estimate herd prevalence of subclinical FE as well as the specificity and sensitivity of the activity in serum of GGT or GDH alone, and of GGT and GDH activities combined, as diagnostic tests for subclinical FE.

RESULTS

The latent class analysis estimated the true prevalence of subclinical FE in the study population as 47.5 (95% probability interval (PI) = 38.3-55.3)%. There was no evidence of any clinically relevant difference between GGT and GDH activities as predictors of subclinical FE; the difference between the areas under the receiver operating characteristic curves for the two measures was 0.005 (95% PI = -0.02 to -0.03). Using the two tests in parallel, with a threshold of 50 IU/L for GGT and 225 IU/L for GDH resulted in specificity and sensitivity of >95%, markedly increasing the accuracy of diagnosis of subclinical FE compared to using GGT or GDH alone at any threshold.

CONCLUSIONS AND CLINICAL RELEVANCE

In this herd, combining the two tests resulted in a clinically relevant improvement in the accuracy of diagnosis of subclinical FE compared to using either test alone, which if used at the individual level will result in fewer cattle being assigned the wrong FE status. This will also apply at the herd level, with combined testing producing fewer false-positive herd test results than using one enzyme alone. This is particularly important for monitoring the efficacy of FE control measures when the expectation should be that the proportion of cattle with FE is very low.

Copper Toxicity in Horses: Does it Exist?

Copper toxicity is thought to be a rare condition in horses. However, the number of cases diagnosed in Brazil is growing. This article aims to describe cases of copper toxicity involving horses from different geographic locations and discuss findings of physical examinations, differential diagnoses and potential causes. Five cases referred from 4 different properties where at least 15 other horses were affected were described. Hemolytic anemia and hemoglobinuria, presence of Heinz bodies and elevated aspartate aminotransferase and gamaglutamil transferase levels were detected in all cases. The diagnosis was based on clinical history and signs, laboratory tests results, copper level determination in feed and/or soil and histopathological findings. Two horses progressed to acute death; remaining horses responded to clinical management with or without blood transfusion, depending on disease severity. However, one of these horses, after several returns to the veterinary hospital, was euthanized due to complications. One horse was treated with ammonium tetrathiomolybdate. Two horses had several recurring episodes over the course of several months, an uncommon presentation in ruminants suffering from copper toxicity. Excess copper was associated with soil fertilization with poultry litter or treatment of previous or neighbor crops with copper-containing products. It can be concluded that copper toxicity does occur in horses and may arise from several sources and/or be associated with predisposing dietary factors. Given the growing number of cases, the condition should be included in the differential diagnosis list and proper preventive dietary and pasture fertilization measures adopted.

[Chronic oversupply with copper as a potential herd health problem on a German dairy farm - Diagnostic value of different sample types for assessment of copper supply in dairy cows]

In contrast to sheep, chronic copper oversupply or toxicity represent infrequent events in cattle. This case report describes a chronically elevated exposure to copper arising from excessive supplementation of mineral feedstuff leading to a herd health problem in a German Holstein dairy herd. For diagnosis on herd level, 10 cows of both the close-up (VB) and high-yielding (HL) groups were selected and blood as well as urine samples were collected. Clinical chemistry investigation of these samples only revealed slightly raised activities of liver enzymes in cows of the HL group. Analysis of the total mixed ration (TMR) of both groups revealed a significant oversupply with copper, zinc, cobalt, and selenium. On the basis of these findings, the copper content of urine, feces, pigmented hair as well as plasma ceruloplasmin activity were measured additionally. Liver biopsies were performed in cows of the HL group and in heifers, the latter of which had received a mineral feed for young cattle according to the manufacturer's instructions. Results indicated increased fecal copper in both HL and VB groups as well as above normal or high-normal values of hepatic copper and cobalt resp. selenium, zinc, and manganese in the HL cows. In contrast, heifers had physiological amounts of trace elements in their liver tissues. This report demonstrates the suitability of fecal analysis and TMR for a reliable assessment of copper supply, while blood, urine, and hair failed to represent appropriate sample types. In order to attain a dependable diagnosis of potential copper oversupply, a liver biopsy - which may also be performed in buiatric practice - is deemed necessary.

The association of milk-solid production during the current lactation with liver damage due to presumptive ingestion of spores from Pithomyces chatarum by dairy cattle

AIMS

To determine the association between production of milk solids (MS) and liver damage from facial eczema (FE) in dairy cattle during autumn and to determine the most practical cut-off for serum gamma-glutamyl transferase (GGT) activity in predicting production loss.

METHODS

Farm history and Pithomyces chartarum spore counts identified herds likely to be affected by raised GGT activity in serum during autumn 2018 or 2019. In these herds, a pilot blood sample from 30 cattle was collected, followed by a full herd blood test within 2 weeks if in those 30 cattle one or more had GGT activities >300 IU/L. Individual MS production was measured within -5 - +12 days of a full herd blood test. Information about feeding Brassica spp. was collected from the farmer. Pooled sera from 10 randomly selected cattle from 10/11 farms with GGT >40 IU/L were tested for anti-Fasciola antibodies.

STATISTICAL ANALYSIS

The association of liver damage and production of MS was analysed using mixed linear regression. Potential risk factors included farm, cow age, MS at last herd test before the likely FE risk period, breed of cow and GGT activity. Subsequently, GGT activity thresholds, from 40-400 IU/L, were used to indicate varying severities of liver damage. For each threshold, a mixed linear model using herd test data produced estimated marginal mean differences in MS production for cows above or below threshold. The prevalence of animals above threshold was multiplied by the per cow loss to obtain the reduction in MS/day/100 cows for each cut-off.

RESULTS

The prevalence of animals with GGT activities > 40 IU/L ranged between farms from 11% (45/488) to 96% (139/145), and GGT activities for individual cows ranged from 3 - 6001 IU/L. From the model, an increase of 100 IU/L in GGT activity was associated with a decrease of 0.011 (95% CI = 0.010-0.012) kg MS/cow/day. A GGT activity threshold of 40 IU/L identified the largest association with MS production of 6.14 kg MS/day/100 cows. No evidence of significant liver fluke or brassica toxicosis was found.

CONCLUSION AND CLINICAL RELEVANCE

Liver damage was most likely caused by sporidesmin toxicity and was associated with substantial linear reduction in MS., When assessing the impact liver damage has on herd milk production, threshold and prevalence of animals exceeding threshold should be considered by the practitioner in assessing economically significant facial eczema.

Copper Supplementation, A Challenge in Cattle

Ensuring adequate copper supplementation in ruminants is a challenging task due to the complexity of copper metabolism in these animals. The three-way interaction between copper, molybdenum and sulphur (Cu-Mo-S) in the rumen makes ruminants, particularly cattle, very susceptible to suffering from secondary copper deficiency. Paradoxically, excessive copper storage in the liver to prevent deficiency becomes a hazard when ruminants are fed copper-supplemented diets even slightly above requirements. While cattle were traditionally thought to be relatively tolerant of copper accumulation, and reports of copper poisoning were until recently somewhat rare, in recent years an increased number of episodes/outbreaks of copper toxicity in cattle, particularly in dairy cattle, have been reported worldwide. The growing number of lethal cases reported seems to indicate that copper intoxication is spreading silently in dairy herds, urging the development of strategies to monitor herd copper status and improve farmers' awareness of copper toxicity. In fact, monitoring studies carried out on numerous samples collected from culled animals in slaughterhouses and/or diagnostic laboratories have demonstrated that large numbers of animals have hepatic copper concentrations well above adequate levels in many different countries. These trends are undoubtedly due to copper supplementation aimed at preventing copper deficiency, as dietary copper intake from pasture alone is unlikely to cause such high levels of accumulation in liver tissue. The reasons behind the copper overfeeding in cattle are related both to a poor understanding of copper metabolism and the theory of "if adding a little produces a response, then adding a lot will produce a better response". Contrary to most trace elements, copper in ruminants has narrow margins of safety, which must also be formulated considering the concentrations of copper antagonists in the diet. This review paper aims to provide nutritionists/veterinary practitioners with the key points about copper metabolism in cattle to guarantee an adequate copper supply while preventing excessive hepatic copper loading, which requires à la carte copper supplementation for each herd.

Chronic copper poisoning in beef cattle in the state of Mato Grosso, Brazil

ABSTRACT: Copper is an essential micromineral in animal feed; however, when consumed in excess, it can cause liver necrosis, hemolytic crisis, hemoglobinuric nephrosis and death in cattle. Although uncommon in this species, copper poisoning occurs as a result of exacerbated supplementation, deficiency of antagonist microminerals, or previous liver lesions. An outbreak of chronic copper poisoning is reported in semi-confined cattle after supplementation with 50 mg/Kg of dry matter copper. The cattle showed clinical signs characterized by anorexia, motor incoordination, loss of balance, jaundice, brownish or black urine, diarrhea and death, or were found dead, 10 to 302 days after consumption. Of the 35 cattle that died, 20 underwent necropsy, whose frequent findings were jaundice, enlarged liver with evident lobular pattern, black kidneys, and urinary bladder with brownish to blackish content. Microscopically, the liver showed vacuolar degeneration and/or zonal hepatocellular centrilobular or paracentral coagulative necrosis, in addition to cholestasis, mild periacinal fibrosis, apoptotic bodies, and mild to moderate mononuclear inflammation. Degeneration and necrosis of the tubular epithelium and intratubular hemoglobin cylinders were observed in the kidneys. Copper levels in the liver and kidneys ranged from 5,901.24 to 28,373.14 μmol/kg and from 303.72 to 14,021 μmol/kg, respectively. In conclusion, copper poisoning due to excessive nutritional supplementation is an important cause of jaundice, hemoglobinuria, and death in semi-confined cattle.

Chronic copper toxicosis in a crossbred heifer calf

An 8-mo-old, crossbred, heifer calf was presented to the Heeke Animal Disease Diagnostic Laboratory with a history of ataxia and altered mentation. Grossly, the liver was diffusely yellow-orange, turgid, and exuded watery, thin blood on cut section. The cortex and medulla in both kidneys were diffusely and markedly dark brown to black. The urinary bladder was filled with dark red urine. Histologically, centrilobular hepatocellular degeneration was observed, but these sections lacked necrosis. In the kidney, numerous cortical tubules contained intraluminal bright eosinophilic fluid and red-orange granular casts that stained positive for hemoglobin with the Dunn-Thompson method. The gross and histologic lesions supported a high level of suspicion for copper toxicosis. Feed and water samples from the farm were submitted for mineral analysis. The copper concentration in the feed was 118 mg/kg, and the molybdenum concentration was 0.9 mg/kg. Chronic copper toxicosis is rarely reported in cattle. The gross lesions in our case are a departure from, although similar to, previously reported cases, including lack of histologic hepatocellular necrosis. Collectively, gross and histologic lesions were compatible with copper toxicosis in this calf, and copper concentrations in the feed samples suggest a feed-mixing error.

Levels of trace elements and potential toxic elements in bovine livers: A trend analysis from 2007 to 2018

Trace elements and potential toxic elements were analyzed in bovine livers submitted for autopsy in the Netherlands during the years 2007 to 2018. The age of each animal was recorded. In total, 1544 livers were analyzed for cadmium, cobalt, chromium, copper, iron, molybdenum, nickel, lead, selenium and zinc. Less than 2% of the liver samples were from veal calves. Young animals had significantly higher concentrations of iron and zinc in their livers compared to animals older than one year, while older animals had significantly higher levels of cadmium and molybdenum in their livers. Animals aged 1 to 2 years had the lowest copper and selenium levels. There was a tendency for lower chromium and nickel levels during the last years of the testing period, while copper showed an increase. Lead intoxication was only seen in the youngest group of cattle, while copper intoxication, defined as a liver copper of more than 1000 mg/kg dry matter, occurred in older animals, mainly in animals of 3 to 4 years old. This trend analysis of trace elements in bovine livers of cattle over time in recent years, and the relation of liver element concentrations with age of the animal, provides insight in the uptake and storage of these elements by cattle in The Netherlands. Possible reasons for observed trends and age-related patterns are discussed.

Effect of sodium molybdate supplementation on high concentrations of Cu in liver of yearling bulls

AIM

To determine the impact of sodium molybdate treatment, given weekly, on concentrations of Cu in liver, activity of liver enzymes, and weight gain over 4 weeks, in yearling bulls with elevated concentrations of Cu in liver.

METHODS

The study was carried on two commercial grazing farms in the Otago region of New Zealand in yearling Friesian bulls (n=150 on Farm A and n=49 on Farm B) with mean concentration of Cu in liver >3,000 µmol/kg fresh weight. On Day 0, all animals were weighed and half were systematically allocated to treatment with sodium molybdate (3 mg/kg liveweight on Farm A and 7 mg/kg liveweight on Farm B); the remainder received no treatment (Control). Sodium molybdate was given as a drench weekly for 4 weeks and all animals were weighed again on Day 28. Ten animals on each farm (five from each treatment group) were systematically selected for blood sampling and liver biopsies on Days 0 and 28. Samples were analysed for concentrations of Cu in plasma, vitamin B₁₂ in serum, activities of γ-glutamyl transferase, aspartate aminotransferase and glutamate dehydrogenase in serum, and concentrations of Cu and vitamin B₁₂ in liver. Separate multivariable linear models were used to compare the change in outcome variables between Days 0 and 28 between bulls that had been drenched with sodium molybdate or not.

RESULTS

On Farm A, mean concentrations of Cu in liver on Day 28, as a percentage of concentrations on Day 0, for the control group was 55 (95% CI=40-73)% and for the treatment group was 73 (95% CI=43-111)%. On Farm B, the equivalent mean for the control group was 75 (95% CI=42-131)% and for the treatment group was 85 (95% CI=38-134)%. The multivariable linear models indicated that the changes in concentrations of Cu in liver, activities of liver enzymes and weight gain between Days 0 and 28 did not differ between the bulls treated or not with sodium molybdate (p>0.18).

CONCLUSIONS AND CLINICAL RELEVANCE

Treatment with sodium molybdate in one bolus at weekly intervals for 4 weeks did not affect concentrations of Cu in liver, activity of liver enzymes or weight gain in animals with high concentrations of Cu liver on two farms.

Invited review: Mineral absorption mechanisms, mineral interactions that affect acid-base and antioxidant status, and diet considerations to improve mineral status

Several minerals are required for life to exist. In animals, 7 elements (Ca, P, Mg, Na, K, Cl, and S) are required to be present in the diet in fairly large amounts (grams to tens of grams each day for the dairy cow) and are termed macrominerals. Several other elements are termed microminerals or trace minerals because they are required in much smaller amounts (milligrams to micrograms each day). In most cases the mineral in the diet must be absorbed across the gastrointestinal mucosa and enter the blood if it is to be of value to the animal. The bulk of this review discusses the paracellular and transcellular mechanisms used by the gastrointestinal tract to absorb each of the various minerals needed. Unfortunately, particularly in ruminants, interactions between minerals and other substances within the diet can occur within the digestive tract that impair mineral absorption. The attributes of organic or chelated minerals that might permit diet minerals to circumvent factors that inhibit absorption of more traditional inorganic forms of these minerals are discussed. Once absorbed, minerals are used in many ways. One focus of this review is the effect macrominerals have on the acid-base status of the animal. Manipulation of dietary cation and anion content is commonly used as a tool in the dry period and during lactation to improve performance. A section on how the strong ion theory can be used to understand these effects is included. Many microminerals play a role in the body as cofactors of enzymes involved in controlling free radicals within the body and are vital to antioxidant capabilities. Those same minerals, when consumed in excess, can become pro-oxidants in the body, generating destructive free radicals. Complex interactions between minerals can compromise the effectiveness of a diet in promoting health and productivity of the cow. The objective of this review is to provide insight into some of these mechanisms.

Assessment of Cu-Zn EDTA Parenteral Toxicity in Calves

Copper (Cu) parenteral administration is used in a beef cow-calf operations to prevent or correct Cu deficiency in bovines. At present, Zinc (Zn) salts have been incorporated to complement Cu antioxidant effect. A risk of hepatotoxicity generated by overdose is a negative consequence of injectable Cu application. Cu-Zn EDTA appears as an alternative; however, data about its toxicity is unknown. The aim of this study was to assess toxicity risk of different doses of Cu-Zn EDTA in calves. Thirty two Aberdeen Angus calves of 162 (±20) kg BW were assigned to 4 groups (n = 8), homogeneous in weight, sex, and age. Cu-Zn EDTA was administrated in doses of 0.3 mg/kg BW (group 1X); 0.6 mg/kg BW (group 2X); 0.9 mg/kg BW (group 3X) and sterile saline solution (control group-with no treatment). Clinical and blood parameters in animals were monitored during 28 days. In groups' control, 1X and 2X there were no alterations in the assessed parameters. In group 3X, one of the animals showed depression, permanent decubitus, and muscular twitching; that animal had to be killed in extremis for humanitarian reasons. Necropsy and Cu tissue concentration findings confirmed intoxication in the clinically affected animal. The rest of the animals in group 3X showed only a temporary increase in liver enzymes. The results indicate that a dose of 0.9 mg/kg BW of Cu as Cu-Zn EDTA is potentially hepatotoxic, this dose is similar to other soluble salts of parenteral administration.

Liver copper concentrations in cull cattle in the UK: are cattle being copper loaded?

With the release of the Department for the Environment, Food and Rural Affairs/Advisory Committee on Animal Feed Guidance Note for Supplementing Copper to Bovines it was noted that the current copper status of the national herd was not known. Liver samples were recovered from 510 cull cattle at a single abattoir across a period of three days. The samples were wet-ashed and liver copper concentrations determined by inductively coupled plasma mass spectrometry analysis. Breed, age and previous location information were obtained from the British Cattle Movement Service. Dairy breeds had higher liver copper concentrations than beef breeds. Holstein-Friesian and ‘other’ dairy breeds had 38.3 per cent and 40 per cent of cattle above the Animal Health and Veterinary Laboratories Agency (AHVLA) reference range (8000 µmol/kg dry matter), respectively, whereas only 16.9 per cent of animals in the combined beef breeds exceeded this value. It was found that underlying topsoil copper concentration was not related to liver copper content and that age of the animal also had little effect on liver concentration. In conclusion, over 50 per cent of the liver samples tested had greater-than-normal concentrations of copper with almost 40 per cent of the female dairy cattle having liver copper concentrations above the AHVLA reference range, indicating that a significant proportion of the UK herd is at risk of chronic copper toxicity.