Comparing the effects of treatment with ammonium molybdate versus ammonium molybdate and phenoxy-2-methyl-2-propionic acid on liver functions in natural copper poisoning of sheep

Emerging insights into the impacts of heavy metals exposure on health, reproductive and productive performance of livestock

Heavy metals, common environmental pollutants with widespread distribution hazards and several health problems linked to them are distinguished from other toxic compounds by their bioaccumulation in living organisms. They pollute the food chain and threaten the health of animals. Biologically, heavy metals exhibit both beneficial and harmful effects. Certain essential heavy metals such as Co, Mn, Se, Zn, and Mg play crucial roles in vital physiological processes in trace amounts, while others like As, Pb, Hg, Cd, and Cu are widely recognized for their toxic properties. Regardless of their physiological functions, an excess intake of all heavy metals beyond the tolerance limit can lead to toxicity. Animals face exposure to heavy metals through contaminated feed and water, primarily as a result of anthropogenic environmental pollution. After ingestion heavy metals persist in the body for an extended duration and the nature of exposure dictates whether they induce acute or chronic, clinical or subclinical, or subtle toxicities. The toxic effects of metals lead to disruption of cellular homeostasis through the generation of free radicals that develop oxidative stress. In cases of acute heavy metal poisoning, characteristic clinical symptoms may arise, potentially culminating in the death of animals with corresponding necropsy findings. Chronic toxicities manifest as a decline in overall body condition scoring and a decrease in the production potential of animals. Elevated heavy metal levels in consumable animal products raise public health concerns. Timely diagnosis, targeted antidotes, and management strategies can significantly mitigate heavy metal impact on livestock health, productivity, and reproductive performance.

Comparing the effect of ammonium molybdate versus ammonium molybdate and menbutone on hepatic functions of sheep with subclinical copper poisoning

This study aimed to investigate the effect of using menbutone in addition to ammonium molybdate on liver enzymes in sheep naturally poisoned with copper. Merino lambs (n = 30), naturally poisoned with copper and which also had high liver enzyme levels, were divided into two groups, each with 15 lambs. The AM + MEN group received ammonium molybdate and menbutone and the AM group received only ammonium molybdate solution. Both groups received 1.7% ammonium molybdate solution (1 mL per 10 kg body weight [BW]) subcutaneously on 0, 2nd and 4th days of the study. Menbutone (Genabil®, Boehringer Ingelheim, Germany) was administered intramuscularly at a dose of 10 mg/kg BW on days 0 and 2, in addition to ammonium molybdate in the AM + MEN group. Blood samples were collected on days 0 and 7, and aspartate aminotransferase (AST), gamma-glutamyltranspeptidase (GGT) and creatinine levels were evaluated. Over 7 days, AST levels decreased from 351.04 ± 63.50 IU/L to 286.40 ± 55.68 IU/L in the AM group (P > 0.05) and from 425.00 ± 119.25 IU/L to 240.83 ± 29.62 IU/L in the AM + MEN group (P ≤ 0.05). GGT levels decreased from 121.16 ± 15.88 IU/L to 110.39 ± 10.13 IU/L in the AM group (P > 0.05) and 124.52 ± 15.50 to 98.60 ± 9.08 IU/L in the AM + MEN group (P ≤ 0.05). Based on these findings, the use of menbutone, in addition to ammonium molybdate, has significantly reduced the level of liver enzymes.

Copper Poisoning, a Deadly Hazard for Sheep

Simple Summary

Sheep are very susceptible to copper intoxication, a deadly disease that causes significant economic losses worldwide. Two types of copper poisoning can occur depending on the chronic or acute exposure to copper. Chronic toxicosis is the most common form and is developed after a long subclinical period of copper accumulation in the liver. When the capacity of the liver for copper storage is exceeded, a sudden release of copper into the blood causes severe haemolysis and the death of the animals. Acute copper poisoning is much less frequent and appears following the accidental administration or ingestion of toxic amounts of copper. Collapse and death occur shortly after parenteral administration, whereas acute oral exposure to copper causes severe gastroenteritis followed by shock and death. In this review, we summarise the available information on the aetiology, epidemiology, pathogenesis, clinical features, diagnosis, treatment and prevention of sheep copper poisoning.

Abstract

Copper (Cu) is an essential microelement for animals. However, sheep are particularly susceptible to Cu intoxication, a deadly disease reported worldwide. The risk of developing this poisoning is higher in vulnerable breeds and in intensively managed lambs or milk sheep. Two types of Cu intoxication can occur depending on the chronic or acute exposure to Cu. In chronic Cu poisoning (CCP), the most common form, Cu is accumulated in the liver during a subclinical period. A low intake of Cu antagonists (molybdenum, sulphur, iron, or zinc) favours Cu accumulation. The sudden release of Cu into the blood causes acute haemolysis with anaemia, haemoglobinuria, jaundice and death within 1–2 days. Acute Cu poisoning is related to the accidental administration or ingestion of toxic amounts of Cu. Acute oral exposure to Cu causes severe gastroenteritis, shock and death. Collapse and death occur shortly after parenteral administration. The diagnosis is based on history, clinical, gross pathological, histological and toxicological findings. Treatment of sheep with severe clinical signs often has poor success but is very effective during the Cu accumulation phase. Different therapies, based on either chelating agents or Cu antagonists, have been used to treat and prevent CCP.

Dietary Zinc Supplementation to Prevent Chronic Copper Poisoning in Sheep

Simple Summary

Sheep are susceptible to copper toxicosis, a deadly disease that usually occurs when the animals ingest large amounts of this mineral. Considering that the susceptibility of sheep to copper accumulation varies widely among breeds and from animal to animal., we evaluate whether Zn supplementation could be an option as a preventive measure to protect against hepatic Cu accumulation in sheep. Zn at 300 mg/kg dry matter (DM) is useful for preventing excessive hepatic Cu accumulation. Hepatic Cu accumulation is lower in animals receiving the Zn supplementation.

Abstract

The aim of this study was to evaluate whether zinc (Zn) supplementation protects against hepatic copper (Cu) accumulation in copper-loaded sheep. Forty cross-bred lambs were assigned to five experimental groups. These included the control group (C) and four treatment groups that received Cu and/or Zn supplementation (dry matter (DM) basis) over 14 weeks, as follows: Cu (450 mg Cu/kg); Zn-35 (450 mg Cu + 35 mg Zn/kg); Zn-150 (450 mg Cu + 150 mg Zn/kg); and Zn-300 (450 mg Cu + 300 mg Zn/kg). Blood, liver, and bile samples were obtained for mineral determination by inductively coupled plasma optical emission spectrometry (ICP–OES). The hepatic metallothionein (MT) concentrations were also determined. At the end of the experiment, hepatic Cu concentrations were higher in all Cu-supplemented groups than in C. Hepatic Cu accumulation was lower in the groups receiving the Zn supplementation than in the Cu group, although the difference was only statistically significant (66%) in the Zn-300 group. The MT concentrations tended to be higher (almost two-fold) in the Zn groups (but were not dose related) than in the C and Cu groups, and they were related to hepatic Zn concentrations. Zn supplementation at 300 mg/kg DM is useful for preventing excessive hepatic Cu accumulation in sheep exposed to high dietary concentrations of Cu.