072 Insect larvae fed mycotoxin-contaminated wheat – A possible safe, sustainable protein source for animal feed?

Abstract

Demand for increased food production, particularly protein, is increasing with the world's growing population. Alternative and sustainable sources of animal protein will be required to reduce environmental impacts of conventional livestock production. Historically, insects have been typical dietary components within eastern countries, and their nutritional value is proportionally comparable to that of conventional meat. The yellow mealworm (Tenebrio molitor) is an edible insect, rich in CP and crude fat. Moreover, there is evidence that mealworms are able to use mycotoxin-contaminated wheat as a food source without accumulating the mycotoxins, thus providing a value for low-grade wheat along with a more sustainable and cheaper source of CP for animal feed. The aim of this study was to measure production traits and survivability and to determine whether mealworms can detoxify mycotoxins (specifically deoxynivalenol [DON]) when fed Fusarium-damaged, high-mycotoxin wheat. To achieve these objectives, naturally contaminated grain was sorted to obtain 4 levels of DON: control (0.2 ppm), low (2 ppm), medium (10 ppm), and high (12 ppm). These levels were fed to larvae (seventh to ninth instar) per replicate for feeding (n = 300) and breeding (n = 200) trials. Each treatment was replicated 5 times and the endpoint for both experiments was when 2 pupae where observed (mean = 32.8 ± 3.2 d). Larvae were fasted for 24 h and frozen prior to mycotoxin analysis by HPLC/mass spectrometry. Fusarium graminearum was culture isolated from highly chalky damaged kernels. Survival rate tended to be higher in the high diet treatment than the other treatments (P = 0.0534) when using the GLIMMIX procedure in SAS. Mean ADG was estimated as 604.9542 mg/d per replicate (300 larvae), and there was no significant difference between treatments (P = 0.1489). Nevertheless, the feed conversion ratio was significantly higher for the low mycotoxin diet (mean = 84.6141, P = 0.0001) when compared with other treatments. Conversely, DON was measurable within the mealworms across all replicates with a mean of 0.1291 ppm and a range of 0.0977 to 0.1902 ppm with 6.3, 1.2, and 1.1% of ingested DON detected in dry bodies from low, medium, and high mycotoxin diets, respectively. Notably, DON concentrations were not significantly different between diets (P = 0.8828) and are far below the regulatory limits for food or feed. From our research, Tenebrio molitor does not appear to accumulate harmful mycotoxins when fed highly contaminated grain and, with further research, could conceivably be used as a sustainable, safe protein source in animal feed.