One power of reconstructing diets with sequencing is to know what an animal had recently ate. Even more powerful is reconstructing diets for a large number of animals to infer how diets change over space or time.
In the global change world, it is an open question about how warming will affect the diets of animals. To test this, we worked with Texas A&M’s GANLab to sequence the fecals of cattle across the central US.
Geographic trends in individual OTUs were evident. For example, species like the cool-season grass Bromus were dominant in the northern grasslands.
When we put all the data together, it was clear that northern cattle relied more on grasses than southern cattle. Cattle in southern, warmer sites typically consumed a greater proportion of forbs and woody species in their diet.
The paper also showed that certain species were indicative of low-quality diets, which could benefit ranchers in improving the nutrition of their cattle.
The inference from this work is that warming favors consumption of non-grasses. Why this is was beyond the scope of this particular project, but even being able to reconstruct the diet of any species across such a large geographic gradient is a major advance in and of itself.