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Abstract

Abbreviations: HC, high concentrate; RT, rumination time; DMI, dry matter intake; NEB, negative energy balance The role of ruminants on global food systemSince the beginning of the 20 th century manuscripts explore the importance of ruminants supporting the man 1,2 and as a major global element in agricultural economy.3-5 Recent studies have predicted that to reach the future demand of animal protein for the next 30years, it is necessary to increase animal protein production in more than double by 2050.6-8 Recently we have reviewed ruminant adaptations and evolution throughout the centuries and the new scenario of diets provoking morphological changes in the digestion and feed behavior in domestic ruminants. 9 Hence, this new situation indicates that feeding a long-term high-concentrate (HC) diet, induces cellular damage on both ruminal and colonic epithelium in goats, 10 and in genes that regulate thickness of the ruminal epithelium in cows.11 Therefore, despite the fact that dietary changes and nutritional shifts can increase the chance of ruminal/metabolic diseases, and may cause more drastic modifications to the future evolutionary adaptations of ruminant digestive system, 9,12 new approaches of evaluating ruminal behavior may be a strong marker to predict the risk of diseases and suitable herd welfare.13-16 Hence, this review aims to provide recent information of the associations between ruminal behavior and metabolic disorders. In addition, show the relations among the new approaches of monitoring ruminal function, predicting the risk of diseases. Variables that can influence ruminationThe rumination process is essential to fore stomach animals as the key event to keep a perfect function of the pre-stomachs. This process works not only to break down fiber in forage feeds, but also to maintain several aspects of metabolic balance as; the ideal ruminal pH, ruminal turnover, re-absorption of nitrogen through the urea cycle, and as a sensible measurement of acceptable herd welfare. 13,17,18 Rumen motility can be divided into primary contractions, which affect the whole reticulorumen, and secondary movements, which affect only a part of the organ. The ruminal motions depends on the activity of the animal, whether eating, ruminating or resting, and it requires up to 50seconds to complete a total cycle. 18 The variability of negative influences in the normal functioning of the rumination process is caused by many factors including acute stress, ethological behavior, diet quality and composition, production level, climatic condition, reproduction and health status.19-22 These variables can cause metabolic changes as a response, including reduction in blood flow to rumen epithelium and diminished rate of digesta in the gastrointestinal tract.22-24 In cases of indigestible residues, reticulorumen mixing and rumination together promote its turnover, which, if allowed to accumulate, would clot the rumen. The consequence of these changes is a depression of rumination time (RT), which subsequently leads to a reduction o...