It should be obvious that nutrient requirements of dairy cattle are the same as they have always been; we are the ones slowly advancing our understanding of those requirements. The purpose of the various editions of the National Academy of Science/National Research Council publication on the nutrient requirements of dairy cattle is simple. Users of that system must be able to predict how cattle will perform for a given set of inputs and able to predict what those inputs should be for a given output.

While it is well-known that the rumen has a complex microbiome (primarily bacteria and protozoa), the diversity of microorganisms found in the lower gut is less appreciated. However, the maintenance of a well-balanced microbiome in the lower gut may be as important to animal health and feed utilization as is the maintenance of a stable rumen microflora.

The American Society of Animal Science and the American Dairy Science Association held their joint annual meeting from July 19 through July 24 in Kansas City, Missouri. Numerous scientific papers on the topic of nutrition were presented and, while many were of interest to our readers, we chose to report on three. In two of these papers, researchers examined the role of dietary starch and its impact on milk production and animal health, and the other dealt with methane production.