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Evaluating the Effects of Pelleting Deoxynivalenol-Contaminated DDGS with Sodium Metabisulphite on Analysed DON Levels

28 February 2012, at 12:00am

Conditioning temperature and retention time alone did not affect levels of the mycotoxin, deoxynivalenol (DON), in dried distillers grains with solubles (DDGS) from maize but pelleting DDGS reduced DON levels as the level of sodium metabisulphite (SMB) was increased to 2.5 per cent, according to research summarised in the latest newsletter from the Department of Animal Sciences and Industry at Kansas State University.

Deoxynivalenol (DON), also known as vomitoxin, was prevalent in the 2009 US corn crop and subsequently present in dried distillers grains with solubles (DDGS), in which DON levels are about three times higher than the original corn source.

One method previously shown to reduce DON levels was by increasing moisture and temperature when sodium bisulphite was added to DON-contaminated maize and the Kansas group set up a pilot study, firstly to replicate these results by placing DON-contaminated DDGS in an autoclave (60 minutes at 250°F) in the presence of sodium metabisulphite (SMB).

The study used six treatments: (1) control; (2) 0.5 per cent SMB; (3) 1.0 per cent SMB; (4) 2.5 per cent SMB; (5) 5.0 per cent SMB and (6) 5.0 per cent SMB with 100mL per kg water added to evaluate the role of water.

After drying, samples were analysed at North Dakota State University Veterinary Diagnostic Laboratory (NDSU; Fargo, ND).

Autoclaving reduced DON levels (R2=0.99) with increasing SMB, justifying a follow-up study that aimed to assess whether SMB has the same detoxifying effects on corn DDGS in a commercial pellet mill.

For this study, batches of 450lb DDGS were prepared from DDGS with a known DON concentration (23.4ppm). The pellet mill was set to a production rate of 1,000lb per hour so retention rate and conditioning temperature could be altered within each batch.

Within each batch, four samples were collected at conditioning temperatures of 150 and 180°F and retention times of 30 and 60 seconds within each temperature. Samples were sent to NDSU for full mycotoxin analysis.

No differences (P>0.15) were found in conditioning temperature or retention time on total DON, DON, or acetyl–DON. However, pelleting DDGS reduced (quadratic; P<0.01) DON and total DON as SMB increased.

Based on these results, the reduction in DON and total DON levels appear to plateau somewhere between SMB levels of 2.5 and 5.0 per cent.

These results imply that pelleting in combination with SMB may allow pork producers to utilise DON–contaminated DDGS more effectively, but additional research is required to determine the effect of pelleting SMB in DON-contaminated diets on growth performance of pigs.

The study was conducted by H.L. Frobose, M.D. Tokach, E.L. Hansen, L.J. McKinney, J.M. DeRouchey, S.S. Dritz, R.D. Goodband and J.L. Nelssen.

February 2012