Conventional research and models have extensively and exclusively focused on non-chronological controllers of feed intake. Natural diurnal patterns of grazing and rumination lead innovative approaches in the intensive systems production. Ruminants have evolved to ruminate mostly overnight and graze during day, especially around sunrise and sunset. Accordingly, rumen fermentation, post-rumen nutrient assimilation and peripheral metabolism possess circadian patterns. This book is a concise and extracted collection of the latest advancements and insights into the global multifaceted science of feed intake regulation in food-producing ruminants. Accurate feed intake prediction is a must for accurate meeting of nutrient requirements and for both economical and environmental sustainibility of the postmodern ruminnat farming. Such accomplishments are among the most aimed human goals in efficiently utilizing natural resources. Ruminants possess highly significant roles in supplying safe and secure foods for human populations worldwide.