Diagnosis > Dairy

Mycotoxins in dairy production
Economic losses associated with mycotoxicosis include reduced milk production, reduced fertility, increased somatic cell count (SCC), increased disease susceptibility and reduced longevity.

As ruminant diets generally include both concentrates and forages, which may increase the risk of mycotoxins in comparison with animals that do not consume forages, recognising and analysing mycotoxicosis cases can be very challenging.

The fact that mycotoxins are partially metabolised in the rumen complicates the situation as although this can lead to detoxification it can also result in the production of new and more toxic metabolites. Mycotoxin metabolism in the rumen is highly affected by diet composition and is therefore difficult to predict. In general, metabolism is more efficient at a more neutral rumen pH in comparison to acidic conditions.

The multiplicity of ingredients in complete diets may increase the probability of multiple mycotoxin contamination but decreases the risk of high mycotoxin concentrations because any one feed ingredient is diluted in the final diet. This will often keep very specific mycotoxin symptoms from the herd but will lead to more general symptoms such as suboptimal performance.

As preserved forages are more likely to harbour moulds and associated mycotoxins than dry forages when anaerobic conditions are not strictly controlled, silages do present an enhanced risk of mycotoxin contamination.

Many agricultural and food industry by-products such as fruit pulp and brewery wastes commonly used in ruminant diets are often handled in wet form which means that moulds can grow and mycotoxins be produced during the storage and transport phases. Furthermore, grazing systems cannot be considered completely safe from mycotoxin contamination. Fresh grasses can be contaminated with mycotoxins including fungal endophytes that produce mycotoxins such as ergovaline and lolitrem B, but also the typical Fusarium mycotoxins such as zearalenone or DON.

In dairy production, feed is the key vector bringing mycotoxins into the production system and control strategies should mainly focus on optimising feed quality. However, cases have been reported where significant concentrations of mycotoxins have been introduced into production systems through the bedding. Straw quality should therefore also be considered as a risk factor especially in dry cows which are fed below appetite and therefore consume straw.

To effectively recognise mycotoxicosis, herds have to be carefully inspected for symptoms. Symptoms are often very general and can greatly vary according to the mycotoxins present, making proper diagnosis difficult. Careful recognition of symptoms and blood analyses in combination with adequate feed analyses, provide the most accurate diagnosis of mycotoxicosis.