Effects of deoxynivalenol and fumonisins fed in combination on beef cattle: health and performance indices

Abstract

Interactions between livestock management practices and toxicological outcomes of mycotoxin exposure may explain the range of tolerable toxin levels reported for various species. In the current study, we investigated the effect of concurrent mycotoxin exposure with a high starch diet in 12 beef steers in a partial cross-over experiment using a 21-day treatment period, followed by a 14-day clearance. During the treatment period, animals were assigned to one of two diets: a low mycotoxin control total mixed ration (TMR) (0.2±0.1 mg deoxynivalenol (DON) and 0.2±0.2 mg fumonisins (FUM)/kg TMR) and a high mycotoxin TMR treatment (1.7±0.2 mg DON and 3.5±0.3 mg FUM/kg TMR). We evaluated the impacts of these mycotoxins on performance, physiology and biochemistry; and the ability of the clearance period to return animals to a naïve state in the cross-over model. The lack of acute ruminal acidosis observed indicates that the animals were able to withstand the physiological stresses of the high starch diet, while toxicological outcomes were manifested in minor perturbations of biochemistry and outright performance of exposed animals. Aspartate aminotransferase, cholesterol, fibrinogen and leukocyte count were increased while sorbitol dehydrogenase, bile acids and mean corpuscular volume were decreased in treatment-fed steers, yet were not significantly different than those from control-fed animals.Fusarium toxin exposure significantly decreased ruminal fluid pH, with the clearance period returning animals to a naïve state, as it did for most of the molecular variables measured. Conversely, treatment-fed animals continued to exhibit significantly lower average weekly body weight throughout the treatment period and the first week of the clearance period. While the risk of adverse health effects to fattening cattle from similar doses of DON or FUM as used in the current study is considered low, additional work should be directed towards minimising production losses due to these feed contaminants.