Review on Mycotoxin Issues in Ruminants: Occurrence in Forages, Effects of Mycotoxin Ingestion on Health Status and Animal Performance and Practical Strategies to Counteract Their Negative Effects

Ruminant diets include cereals, protein feeds, their by-products as well as hay and grass, grass/legume, whole-crop maize, small grain or sorghum silages. Furthermore, ruminants are annually or seasonally fed with grazed forage in many parts of the World. All these forages could be contaminated by several exometabolites of mycotoxigenic fungi that increase and diversify the risk of mycotoxin exposure in ruminants compared to swine and poultry that have less varied diets. Evidence suggests the greatest exposure for ruminants to some regulated mycotoxins (aflatoxins, trichothecenes, ochratoxin A, fumonisins and zearalenone) and to many other secondary metabolites produced by different species of Alternaria spp. (e.g., AAL toxins, alternariols, tenuazonic acid or 4Z-infectopyrone), Aspergillus flavus (e.g., kojic acid, cyclopiazonic acid or β-nitropropionic acid), Aspergillus fuminatus (e.g., gliotoxin, agroclavine, festuclavines or fumagillin), Penicillium roqueforti and P. paneum (e.g., mycophenolic acid, roquefortines, PR toxin or marcfortines) or Monascus ruber (citrinin and monacolins) could be mainly related to forage contamination. This review includes the knowledge of mycotoxin occurrence reported in the last 15 years, with special emphasis on mycotoxins detected in forages, and animal toxicological issues due to their ingestion. Strategies for preventing the problem of mycotoxin feed contamination under farm conditions are discussed.

Mycotoxin syndrome in dairy cattle: characterisation and intervention results

In daily practice, dairy cattle may be exposed to complex mixtures of mycotoxins originating from pre- and postharvest contamination of roughages, silage and concentrates. In particular silage has been identified as a source of different microbial toxins, which may impair animal health and productivity. The aim of the current study was to identify functional and descriptive biomarkers for the mouldy silage syndrome in dairy cattle. Such biomarkers should also serve as indicators of the beneficial effects of intervention strategies. In a field trial, a total of 87 cows from three different farms were enrolled in the study. From these animals blood samples were collected at three different time points and subjected to multiple biochemical analyses. Within this group, fine needle liver biopsies were obtained from 43 animals and subjected to biochemical analyses and targeted gene expression profiles. The measured parameters represent biomarkers of inflammation, oxidative stress, gluconeogenesis and lipids. In the affected animals, oxidative stress and a dysfunction in lipid metabolism were observed, marked by significantly decreased levels of glutathione peroxidase (GSH-Px) activity, glucose-6-phosphate-dehydrogenase (G6PD) concentrations and trolox equivalent antioxidant capacity (TEAC) and significantly increased concentrations of free cholesterol in plasma, together with a decreased activity of phospholipid transfer protein (PLTP) and lecithin-cholesterol acyltransferase (LCAT). When a glucomannan mycotoxin absorbent was added to the daily ration for a period of 8 weeks most of these biochemical markers gradually improved to normal levels, and body condition and milk yield improved. The obtained results contribute to the understanding of the pathophysiological changes associated with multiple mycotoxin exposure in dairy cows and allow a refined assessment of intervention strategies under field conditions.

Nodding syndrome in Mundri county, South Sudan: environmental, nutritional and infectious factors

BACKGROUND

Nodding Syndrome is a seizure disorder of children in Mundri County, Western Equatoria, South Sudan. The disorder is reported to be spreading in South Sudan and northern Uganda.

OBJECTIVE

To describe environmental, nutritional, infectious, and other factors that existed before and during the de novo 1991 appearance and subsequent increase in cases through 2001.

METHODS

Household surveys, informant interviews, and case-control studies conducted in Lui town and Amadi village in 2001-2002 were supplemented in 2012 by informant interviews in Lui and Juba, South Sudan.

RESULTS

Nodding Syndrome was associated with Onchocerca volvulus and Mansonella perstans infections, with food use of a variety of sorghum (serena) introduced as part of an emergency relief program, and was inversely associated with a history of measles infection. There was no evidence to suggest exposure to a manmade neurotoxic pollutant or chemical agent, other than chemically dressed seed intended for planting but used for food. Food use of cyanogenic plants was documented, and exposure to fungal contaminants could not be excluded.

CONCLUSION

Nodding Syndrome in South Sudan has an unknown etiology. Further research is recommended on the association of Nodding Syndrome with onchocerciasis/mansonelliasis and neurotoxins in plant materials used for food.