Smart Sheep Learn About Foods that Cause Bloat

bloated sheepBloat is a big problem for producers. Last summer, Dr. Juan Villalba investigated if ruminants can learn which foods to eat to relieve the effects of bloat.  His results provide a new understanding of how animals form food aversions and preferences and have Juan thinking about the next steps in teaching animals to alleviate bloat.

Juan’s experiment used lambs with rumen cannulas and balloons. Here’s how it worked:  Balloons that could be inflated or deflated were placed in the lambs’ rumens. Lambs were then fed one food and the balloon was inflated to simulate bloat’s effects. Next the lambs were fed a different food and the balloon was deflated to relieve their bloat. 

Once the lambs were conditioned to the “bloat food” and the “relief food” they were given a choice of the two foods.  What the lambs ate was monitored to see what they learned from their experiences.

Surprisingly, animals formed strong aversions to the foods associated with inflation of the balloon and gut distension.  This is significant because researchers knew that rumen distension reduces food intake but didn’t know that it can cause food aversions and affect diet selection (figure 1).

Lambs also formed a strong preference for foods associated with deflation of the balloon (relief).  In addition, just like we do as our stomachs get full at mealtime, the more air pumped into the balloons, the less food lambs ate.

Now that we know animals can learn to choose foods based on the effects of bloat, the next step is to translate this to the field.  Soon we may know if animals can learn to mix birdsfoot trefoil with their alfalfa to prevent bloat.

Reference: Villalba, J. J., Provenza, F. D., & Stott, R. 2009. Rumen distension and contraction influence feed preference by sheep. Journal of Animal Science, 87:340-350.

Figure 1: Lambs that experienced bloat (graph on left) had a strong preference for the food that provided relief from bloat, whether or not the balloon was inflated.  Lambs that did not experience bloat had equal preferences for the two foods (graph on right).