Dairy Nutrition Management

Food Animal

20TH ANNIVERSARY

Compendium September 1999

Highlights and Horizons in

Dairy Nutrition Management James A. Jarrett, DVM Executive Vice President American Association of Bovine Practitioners Rome, Georgia

oc, why can’t we prevent milk fevers instead of having to treat so many?” a dairy producer asked his veterinarian. Another client wondered: “Why do our cows have so many retained placentas, and why so many fat cows at calving?” Thus was borne the incentive for bovine practitioners to become involved with dairy nutrition. Until the early 1960s, veterinarians in food animal practice devoted most of their time to treating sick animals. At about that time, however, many dairy practitioners started to explore ways to prevent disease rather than spending so much time and effort prescribing and delivering therapy.

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It All Started with Mastitis Early preventive medicine efforts were centered primarily on controlling and preventing mastitis—a very costly disease to dairy farmers. As mastitis was brought more under control, it became apparent that such metabolic and nutritional diseases as hypocalcemia (milk fever) and rumen acidosis were also costing dairy producers considerably; at the time, however, exact losses had not been established. It has been my experience that any health event in a given lactation (e.g., a single case of milk fever or acute rumen acidosis) can result in a substantial production loss. During the 1960s, feeding protocols for dairy cows were going through transition. One of the more notable changes was the use of mixer devices adapted from the feedlot industry, along with total mixed rations (TMRs). Most dairy cows had previously been fed a limited amount of grain in the milking barn or parlor while they were being milked; and the remainder of the diet, mostly forage, had been fed at a different location. Such practice made for the possibility, and in many cases probability, of extreme changes in rumen pH and associated

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ANNIVERSARY

Before 1950 Most dairy cows are fed by grazing forages and receive a limited supplement of simple grain mixtures at milking time

1950s Cows are fed increasing amounts of grain, but most forage continues to be supplied as grazing; veterinary service to dairies is limited almost totally to treating sick animals

James A. Jarrett, DVM

health problems, including rumen acidosis and fat-cow syndrome. Early TMRs were usually just a mixture of the former ration components that had been fed separately. To further complicate matters, rations at that time were often high in energy and low in protein and effective fiber. Even in many high-producing herds, total dry-matter intake did not exceed 14% crude protein. Today, the rations fed to many high1960s Dairy herds become larger but are confined to smaller spaces, necessitating feed being carried to cows rather than cows grazing; total mixed rations (TMRs) are first used on dairy farms, and mixer trucks/wagons are introduced to deliver dairy rations; veterinarians become more focused on disease prevention rather than treatment

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Compendium September 1999

producing cows contain up to 20% crude protein. Much of the forage was corn silage, which was often derived from high-grain varieties of corn and thus led to excessive starch levels in the diet. It has been said that nature abhors a vacuum—a statement that certainly could apply to the situation described. As veterinarians became more frustrated treating nutritional disease and experienced an increasing desire to help their clients, they became determined to learn more about dairy nutrition.

The Role of Veterinary Education Until the late 1970s and early 1980s, most veterinary colleges required preveterinary students to take some introductory courses in animal nutrition. At about that time, however, these requirements began to change. In many cases, specific course work in animal nutrition was deleted from curricula. Students who entered veterinary schools with these limited nutrition requirements could graduate with only minimal additional exposure to ration balancing and other components of animal nutrition. In contrast, veterinary schools today offer, as elective courses, comprehensive programs in ration balancing and animal nutrition. The initial success of the few practitioners who worked with dairy clients on nutrition management, however, soon demonstrated the need for additional education. This demand led to in-depth nutrition seminars offered at several national and regional conferences, with the first program offered at the annual American Association of Bovine Practi-

20TH ANNIVERSARY

tioners (AABP) Conference in St. Louis in December 1977. Instructors for these seminars came from the ranks of successful private practitioners and professional animal nutritionists. Seminars like these continue today: They are offered by the AABP at its annual conference as well as other national and regional meetings and are typically well attended.

Technology to the Rescue Most ration balancing taught prior to the 1970s would be considered very basic by today’s standards, with only three of four nutrients and the major minerals being covered. Thus, the early practitioners performed their calculations by hand or using a slide rule. This trend continued into the mid- or late-1970s, when handheld calculators became more widely available. Programmable calculators marketed primarily by Texas Instruments and Hewlett-Packard soon followed. The advantages of programmable calculators were quickly recognized by at least two enterprising veterinarians—Tim Lesch, DVM, who was at the time affiliated with VirginiaMaryland Veterinary College, and Ben Norman, DVM, who is affiliated with the University of California College of Veterinary Medicine. The Texas Instruments model TI-59 became the de facto standard, and many veterinarians became very proficient at balancing dairy rations using this calculator. The desire to balance an increasing number of nutrients and the need to become more sophisticated in the science of ration balancing eventually demonstrated the limited capacity of programmable calculators. Fortu-

Food Animal

nately, the next generation of technology came in the form of what were called portable personal computers, followed quickly by ration-balancing software. To refer to the early personal computers as portable, however, was a stretch of the imagination. As the late Dr. Ben Harrington, one of the pioneer veterinarians in dairy nutrition, so aptly expressed, these computers would have been better called luggable. The first models were about the size of a small suitcase and weighed from 25 to 30 lb. I can recall carrying my portable computer through airports and onto airplanes. In comparison, the computer I use today weighs less than 3 lb and is less than 1 inch thick. Ah, progress.

Not Simply a Science With the introduction of modern laptop and notebook computers and sophisticated software packages, today’s animal nutritionists—both veterinarians and specialists—can complete very in-depth ration balancing. However, they may occasionally forget that there is an art to feeding cows in addition to the science. It is in the execution of the art of nutrition that properly educated and experienced veterinarians can and often do have advantages over other information providers, including extension agents and feed sales staff. Of all the advisors available to dairy producers, veterinarians are usually the most frequent visitors to dairy farms. Veterinarians often are more familiar with the numerous extenuating circumstances (e.g., weather, farm history, labor forces) that can affect dairy management decisions. In addition, because they perform exami-

1992 1995 987 1998 1994 1991 986 19891993 1997 1970s Metabolic diseases in dairy cows resulting from dietary imbalances are diagnosed more often; the first seminars and other continuing education sessions on nutrition are offered by the American Association of Bovine Practitioners and other conferences; TI-59 and other programmable calculators are first used for ration balancing

1990

1980s Portable personal computers are used to balance rations; continuing education in nutrition for practicing veterinarians increases

1990s Notebook and laptop personal computers and specialized software for ration balancing become available; dairy nutrition becomes highly specialized, and more information on nutrient solubility becomes available for ration balancing; dairy veterinarians begin to include nutrition consulting as a major part of their practices

1999

Food Animal

20TH ANNIVERSARY

nations and diagnostic procedures, veterinarians typically have more direct and closer contact with the cows than do the other information providers and are more aware of the metabolic and nutritional diseases that can affect a given dairy farm. Finally, most veterinarians enjoy a high degree of respect by their clients and thus have greater opportunity to execute the art of nutrition management.

Summary The combination of these and other factors has led many veterinarians to include nutrition as a part of their

Compendium September 1999

production medicine programs and in most cases, to a closer relationship with dairy farmers. Today, practitioners have an opportunity to become an integral part of farm management and operations. I have had a greater positive effect on the bottom line of my clients by being involved with their nutrition programs—more so than with any other activity or involvement with the farm and producers. This awareness leads me to believe that practitioners can and should participate with their clients in this most critical part of daily management.