Preface| Volume 29, ISSUE 2, Pxi-xii, July 2013

Metabolic Diseases of Dairy Cattle

      Metabolic disease continues to be a substantial challenge in the dairy industry, not only in North America but also in all other regions in which modern dairy cattle breeds are managed and fed for high milk yields. Undoubtedly, some of this continuing challenge is related to progressive improvement in dairy cow genetics and the ever-increasing average milk yields of modern dairy cattle. Improvements in production capacity challenge us to manage and feed cows to allow them to adapt to the tremendous metabolic demands of high milk production. More than this, however, I believe the continued and perhaps even enhanced interest in metabolic diseases of dairy cattle comes from our expanding understanding of the diverse ramifications of the metabolic events of early lactation. These ramifications go well beyond those associated with traditionally described metabolic diseases, such as milk fever and ketosis, and include the much broader realm of nearly all diseases common to early lactation cows. The intertwining associations among various metabolic stresses and their relationships to other diseases, particularly infectious and inflammatory diseases of early lactation, have now become a central focus of the interest in metabolic diseases of dairy cattle.
      The issue leads off with articles addressing this complex association of metabolism with other health and nutritional challenges to the dairy cow. The article by Lorraine Sordillo and William Raphael illustrates the interrelationship of metabolism and inflammation and describes how metabolic events may lead to altered inflammatory responses and increased susceptibility to infectious diseases. The following article by Michael Allen and Paola Piantoni addresses new concepts in the potential relationship between metabolism and appetite regulation, particularly in early lactation cows. Ideas expressed in this article point to the potential of a “downward spiral” of metabolic events that may diminish feed intake at the exact time when feed intake should be increasing. The contributions by Jenne De Koster and Geert Opsomer, and by JR Roche and coworkers, discuss the long-term implications of body condition and body condition changes, their effects on insulin resistance, and subsequent effects on metabolic health. The articles by Ian Lean and colleagues, in addition to giving many practical recommendations for dry cow feeding and management, also present some new ideas and information describing potential mechanisms for an interrelationship and interaction between mineral and energy metabolism. I believe these articles all broaden the scope of what we’ve traditionally called “metabolic disease.”
      Other articles in this issue describe diagnostic tools for the herd-level evaluation of metabolic status and metabolic disease risk. Some of these are well developed and others are in development. The article by Paula Ospina and coworkers describes rigorous new approaches to the herd-level evaluation of serum nonesterified fatty acid and β-hydroxybutryic acid concentrations. These tests have been in wide application for some time and this article offers new insights, particularly into the herd-level interpretation of these values. The contribution from Giuseppe Bertoni and Erminio Trevisi points out the potential advantages in creating multivariate testing approaches to be applied at both the individual animal and the herd level. In this same vein of describing potentially new testing procedures to aid in the management of metabolic disease in dairy cows, Jenne Koester and Geert Opsomer describe diagnostic tests that may become practical in the field for the evaluation of insulin resistance in cows.
      Finally, several articles in this issue, including some of those mentioned above, include sections describing very practical regimens for the management and prevention of metabolic disease in dairy cows. Included among these are those by Jessica Gordon and colleagues on ketosis therapy and Garrett Oetzel on the prophylactic use of oral calcium supplements.
      I wish to express my admiration for and my appreciation to the contributing authors. They are a distinguished group of international scientists. This issue represents a worldwide contribution to continuing developments in the investigation, management, and prevention of metabolic diseases in dairy cattle.