Dehydration curve, fungi and mycotoxins in tifton 85 hay dehydrated in the fieldandinshed

Abstract

The objective of this study was to estimate the dehydration curve and occurrence of fungi and mycotoxins in Tifton85 hay. The experimental design was randomized blocks in split plots with four replications and fivelevelsofnitrogen(0, 25, 50, 75 and 100 kg ha-1) in the form of urea, two regrowth ages (28 and 35 days) and drying hay in the sun and in shed. After harvesting, the grass was sampled four times (0, 8, 23 and 32 hours) to dry in the sun and twelve times (0, 3, 18, 27, 42, 51, 66, 75, 90, 99, 114 and 123 hours) for drying in shed, turned over daily. The fungi were identifiedafterseedingandgrowth in three steps of haymaking (cutting, baling and after 30 days of storage). To verify the presence of mycotoxins, 20 samples, composed of hay stored for 30 days, were collected, of which 10 samples were from sun-dried hay and 10 from hay dried in shed. It took 32 hours to produce hay at fieldconditions, with water loss rates up to 6.10 g g-1 DM-h during the first8 hours after cutting. The average loss of water in this period was 2.0 g g-1 DM-h. Hays dried in the shed took 123 hours and the dehydration rates were less than 0.5 g g-1 DM-h due to environmental conditions. There was a predominance of three genera of fungi: Fusarium, Penicillium and Aspergillus. The largest population was the Fusarium, followed by Penicillium, at the steps of baling and storage. The fumonisin mycotoxin was found at a higher concentration and there was no difference in fumonisin concentration in the hay dried in the sun and in shed. Although it brings no hazard to animal health, the production of aflatoxinand zearalenone was significantlyhigherinthesamplesofsun-driedhay. © 2013 Sociedade Brasileira de Zootecnia.