Abstract
The objective of this study was to investigate the effect of long-term exposure to a Fusarium toxin deoxynivalenol (DON, 5 mg/kg DM) on the energy metabolism in lactating cows fed diets with different amounts of concentrate. In Period 1 27 German Holstein cows were assigned to two groups and fed a control or mycotoxin-contaminated diet with 50% concentrate for 11 weeks. In Period 2 each group was further divided and fed either a diet containing 30% or 60% concentrate for 16 weeks. Blood samples were collected in week 0, 4, 8, 15, 21, and 27 for calculation of the Revised Quantitative Insulin Sensitivity Check Index and biopsy samples of skeletal muscle and the liver in w 0, 15, and 27 for analysis by real-time RT-qPCR. The DON-fed groups presented lower insulin sensitivities than controls at week 27. Concomitantly, muscular mRNA expression of insulin receptors and hepatic mRNA expression of glucose transporter 2 and key enzymes for gluconeogenesis and fatty acid metabolism were lower in DON-fed cows compared to the control. The study revealed no consistent evidence that DON effects were modified by dietary concentrate levels. In conclusion, long-term dietary DON intake appears to have mild effects on energy metabolism in lactating dairy cows.
Highlights
Deoxynivalenol (DON) is one of the mycotoxins that are most prevalently detected in feedstuffs [1].Among livestock, cattle are less sensitive to DON intoxication due to the detoxification mechanisms in the rumen [2]
The effect of DON and the concentrate levels on dry matter intake (DMI), body weight (BW), milk production performance, and mycotoxin intake have been published by Keese et al [23]
The average DON intake was significantly higher in the cows fed a mycotoxin-contaminated diet compared to the control in Period 1
Summary
Deoxynivalenol (DON) is one of the mycotoxins that are most prevalently detected in feedstuffs [1].Among livestock, cattle are less sensitive to DON intoxication due to the detoxification mechanisms in the rumen [2]. Most of ingested dietary DON is degraded during the process of ruminal microbial fermentation to the by far less toxic de-epoxy-deoxynivalenol DOM-1 [3,4]. The ruminal fermentation pattern, and thereby possibly the ruminal DON degradation capacity, depends on the concentrate proportion of the diet [5,6]. In high-yielding dairy cows, the capacity for ruminal detoxification may Toxins 2018, 10, 188; doi:10.3390/toxins10050188 www.mdpi.com/journal/toxins. Toxins 2018, 10, 188 be restricted by additional metabolic burdens for ruminal microbes, such as concentrate-rich diet, or by faster rumen turnover rates [7]. Varying the dietary proportion of concentrate might influence the detoxification of DON. Ingestion of a DON-contaminated diet affected ruminal fatty acid composition [6] and ruminal protein utilization [3]. Regarding the effects on the liver, no evidence was found for the effects of DON on the integrity and morphology of hepatocytes as assessed by plasma activity of hepatic enzymes and by histopathological evaluation in dairy cattle [8,9]
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