Distillers grains are a main component of feedlot diets, with over 70% of surveyed nutritionists indicating that they include some form of distillers grains in rations at ranges of 10-30%.  The amount of sulfur present in ethanol by-products has led to concern over the occurrence of polioenchephalomalacia (better known as polio; PEM), a neurological condition resulting from either thiamin deficiency or sulfur toxicity. Further, the concentration of hydrogen sulfide gas in the rumen has also been linked to onset of PEM.

Previous research has shown that the level of roughage and sulfur, source of sulfur in the diet, and even sulfur in the water can impact the concentration of hydrogen sulfide in the rumen or increase the risk of PEM.  What research hasn’t explained is why some cattle with relatively low sulfur levels in the diet and reasonably low water sulfur still develop PEM. The objective of our research was to demonstrate how bunk management impacts cattle performance and concentration of hydrogen sulfide gas in the rumen. 

One of the theories that we are testing at the CREC is that conditions which lead to acidosis may be the cause of the more sporadic cases of PEM. One of the major contributing factors to acidosis is poor bunk management.  Thus, our goal in this project was to create ideal bunks (those devoid of feed immediately prior to feeding) or long bunks (those still having feed left at the time of feeding).

We managed cattle in this manner through adaptation (the transition of cattle from high roughage to high concentrate diets). Measuring average daily gain (ADG), dry matter intake (DMI), and hydrogen sulfide gas concentrations throughout the process.  What we found was that ADG and feed efficiency were similar across treatment during the 28d of adaptation (Table 1).  Steers fed under long-bunk management consumed more feed, 27.7lb vs 25.4lb, for Long and Control treatment respectively (DM basis).  Hydrogen sulfide gas concentrations were similar on d 0 and 7 but were 41% greater in long-bunk managed cattle on d 14 and 33% greater in long-bunk managed cattle on d 28 (Figure 1).

The final question is ‘where do we go from here?  The data we gathered indicates that bunk management does impact hydrogen sulfide gas concentrations in the ruminant animal.  Further research will be needed to continue to develop our understanding of how bunk management might impact incidence rates of PEM.  Adding different adaptation strategies or working with greater amounts of distillers grains to see if greater separation of hydrogen sulfide is possible due to management are also future research questions.

Bryan Neville
Bryan.Neville@ndsu.edu
Animal Scientist, CREC

Leslie Lekatz
Assistant Professor University of Minnesota, Crookston