THE MERCK VETERINARY MANUAL
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Beef Feedlots

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In beef feedlots, young growing cattle are fed a high-energy diet to produce marketable beef at a low cost of gain. Depending on the starting body weight and age of the cattle, the period of feeding varies from 60 days to 12 mo. The success of a modern feedlot depends on excellent management, a favorable economic climate, and relative freedom from unfortunate events such as disease epidemics or unexpected increases in costs (eg, feed) or decreases in the price received for the final product. The concept of disease should include all of the identifiable factors that cause suboptimal performance: inadequacies in feeds and feeding systems, the purchase of undesirable types of cattle, and clinical and subclinical disease.

The feedlot veterinarian is responsible for maintaining optimal animal health through the following activities: 1) Making regularly scheduled visits to the feedlot. The frequency of visits depends on the size of the feedlot, the time of year, the expertise of the feedlot personnel, whether animals have recently arrived, and the degree to which the veterinarian is contractually responsible for the total animal health program. 2) Being available for emergency visits to the feedlot when disease epidemics are seen. 3) Performing necropsies during visits and training feedlot personnel to do necropsies at other times. 4) Examining sick animals to ensure that reasonably accurate diagnoses are being made and rational therapy is being given according to established treatment protocol. 5) Regularly examining, analyzing, and interpreting animal health and production data and making recommendations in a written report. The effectiveness of detection of sick animals, based on response and relapse rates and case fatality rates, should be determined, and the effectiveness of the processing program for new arrivals, which includes the vaccines used and the medications given, should be examined and analyzed regularly. 6) Selecting and prescribing all drugs used in the feedlot, giving specific advice about the use of drugs, and establishing a drug residue-avoidance program. 7) Discussing overall animal health and production performance with the feedlot manager and other consultants, setting animal health and production goals, and monitoring achievement. 8) Comparing the feedlot with other operations. The veterinarian should produce a monthly report that compares processing costs, treatment costs, and death loss by arrival weight and days on feed.

When the consulting veterinarian is not readily available, a local practitioner can serve as a valuable resource for the feedlot. Serving as part of the feedlot's health care team, the local veterinarian can make significant contributions to the animal health program.

Economic Impact of Disease

Disease may cause economic loss in feedlots through mortality, treatment cost, or effects on productivity. The impact of clinical and subclinical disease on production efficiency and economic returns may be greater than the losses associated with mortality. A thorough understanding of the impact of disease on animal performance and economic loss is essential to make cost-effective recommendations to feedlot managers. The costs associated with death loss, chronically ill cattle marketed prematurely at a discount, and treatment are obvious and easy to calculate. Hidden costs, such as reduced performance and lower carcass quality, are often overlooked.

Treatment costs are another source of economic loss. Factors influencing the average cost include the morbidity rate, retreatment rate, cost of the drug(s), combination versus single antimicrobial therapy, whether adjunct therapy is used, labor, and feedlot markup on the products used. The morbidity rate has the strongest influence on the average treatment cost for all cattle in the pen. When metaphylaxis is used to manage bovine respiratory tract disease, it must be added to the total medical cost for the pen.

Implementing a Feedlot Medicine Program

Regular inspection of all areas of the feedlot should be included in a feedlot health service. Credit for keen observation and a job well done along with recommendations for improvement in animal husbandry should be noted and recorded for discussion with personnel. Attention should be given particularly to the delivery of feed and water, the general well-being of cattle, and any unusual characteristics of each feeding pen. Many feedlot health problems can be prevented with excellent management.

Continued disease surveillance through regular necropsy examination of all dead cattle and regular observations of sick cattle are necessary. In colder climates, carcasses may freeze solid before the veterinarian is available. Conversely, in warmer climates, carcasses may decompose beyond usefulness. When distance prevents the consulting veterinarian from performing a necropsy on every animal that dies, a more accessible veterinarian may be employed. In many cases, feedlot personnel can be trained to recognize common postmortem lesions, take digital photographs of such lesions and send them to the consulting veterinarian, and collect tissues for potential analysis.

A key to management of disease in feedlots is a fast and accurate diagnosis. This requires a good surveillance system, a systematic plan to search for sick animals, appropriate facilities for examination and treatment, accurate identification of animals, and appropriate laboratory facilities, especially a necropsy service. Emphasis is placed on training and supervising feedlot employees in the detection and early treatment of sick cattle. Employees, particularly any personnel responsible for checking the cattle pens for sick cattle, should be given regular instruction in the clinical signs of common diseases. These include anorexia, depression, lameness or abnormal gait, stiff movement, coughing, nasal and ocular discharge, increased breathing rate, crusted muzzle, sunken eyes, rough hair coat, loose or very firm feces, abnormal abdominal fill, and straining. Cattle with these or other signs of illness are examined more closely in the hospital area and, if necessary, treated. In some feedlots, treated cattle are immediately returned to their original pens, whereas in others cattle are kept in hospital pens until they recover. Most animals that do not recover or that relapse after the first treatment are re-treated, although this decision depends on the nature of the disease and the economics involved. If an animal becomes chronically ill and chances of recovery are slim, it should be sold for slaughter if this is a viable option (after the appropriate withdrawal time) or, in the case of a calf, euthanized.

Pens from which sick animals are taken should be closely observed. A potential epidemic must be identified early so that pen-level intervention can be considered.

Despite its importance, pen surveillance is not highly reliable for the detection of sick feedlot animals, particularly calves in the first week after arrival. It is difficult to distinguish tired, gaunt calves that may have been weaned a few days earlier from calves in the early stage of acute, undifferentiated respiratory disease. As many as 50% of animals pulled from a pen of recently arrived calves will not show clinical signs of respiratory disease based on measurement of body temperature and a cursory clinical examination.

The veterinarian must specify procedures for the clinical management of sick cattle and provide a standard protocol that outlines specific treatments for disease syndromes, including drug dosages, treatment intervals, routes of administration, and withdrawal times. The protocol should be followed strictly by all personnel so that the success or failure of therapy can be evaluated accurately and that chances of creating food safety hazards are zero. The effectiveness of the treatment protocol should be evaluated regularly by determination of the response rates for the various treatment regimens. Failure to develop and implement appropriate treatment protocols often leads to the use of many different drugs indiscriminately, which then leads to excessive treatment costs and often an increase in the case fatality rate.

Feedlot Records

Records are essential to monitor the incidence of disease, response to treatment, and production performance, and they should be analyzed regularly by the veterinarian, nutritionist, and feedlot manager. They can be maintained by hand or by using commercially available computer software. The necessary input records include the lot description, processing record, lot update, sale information, animal identification, and feed and animal health product purchases. The necessary output records include the numbers of animals pulled from each pen daily, from which an epidemic curve can be drawn; the treatment response report according to pen or drug used; the percentage of pulled animals that had a fever, which is an indication of how many are probably affected with an acute respiratory disease rather than a noninfectious disease such as grain overload; the daily mortality report, which should include the list of animals that died, along with their arrival dates, the dates of treatment, and the causes of death; a case abstract of the treatment history of each individual animal; and a close-out summary, which includes all production costs, the health and production performance of the lot or pen of cattle (including morbidity, mortality, ratio of feed conversion to body weight gain, average daily gain), the costs of gain per unit of gain, the number of days on feed, and the profit or loss.

Each animal treated should be individually identified, if this was not done on entry, and the information recorded on the treatment report. Treatment personnel should record the feeding pen, lot number, body temperature, body weight, disease suspected, treatment given, and location of the animal after treatment (eg, which hospital pen). The severity of the illness should be assessed to properly evaluate response to treatment. Late treatment in advanced stages of disease, particularly respiratory disease, is a major cause of failure to respond, even when the treatment of choice is instituted.

A report is filled out for each animal treated, and all subsequent treatments are recorded. The updated reports are retrieved for animals that relapse or die. The cumulative information on the report can be used to decide whether an animal should be culled for chronic or recurring illnesses that are refractory to treatment, to decide on alternative treatments, to explain reasons for death, and to evaluate the effectiveness of the treatments recommended. Some feedlots record animals that are removed from the pen but sent back untreated because they did not meet the temperature criterion in the case definition for a given disease. This information can be of value if the animal is removed again or dies.

This record contains the number of treated cattle by pen and lot number, the disease diagnosed, and the date. It provides both the manager and the veterinarian with a rapid assessment of the location of disease problems in the feedlot. It contains information on the number of animals removed and the number not treated and then classifies those treated according to diagnosis and whether they are a relapse or new case. By using this report in conjunction with an inventory report showing filling dates and numbers added to the pen on those dates, it is possible to generate epidemic curves.

This aggregation of data summarizes the morbidity rate, the relapse rate, and the death rate for a lot or pen of cattle. It is especially important as a tool to evaluate the overall effectiveness of the treatment program for various diseases; the relapse rates and death rates are compared with goals set for the feedlot and with standards published in the literature. The disposition summary alerts the feedlot manager and consulting veterinarian when the results are highly positive, so this feedback can be relayed to all employees to acknowledge their hard work, and when the chronic or culling rates are abnormally high, so that appropriate changes can be made.

The causes of death as determined by necropsy should be summarized on a regular basis. A mortality analysis includes the number of days the animal was in the feedlot, any observed premonitory signs, and treatment (diagnosis, drug used, and when treated). The pen location of the animal in the feedlot at the time of death should also be considered.

Most feedlots complete a close-out summary for each group of cattle that have been finished and marketed. The performance record and feeding summary sections include average daily gain, total feed consumption, feed conversion ratios and cost per unit of body weight gain, mortality rates, culling rate, and medical costs. The financial summary provides the profit or loss on an individual and lot basis. If cattle are marketed on a grid basis with rewards for certain carcass characteristics, this information is also included.

Vaccination Protocols

An important component of feedlot health programs is the planning of vaccination programs. Vaccination schedules vary depending on the prevalence of disease both in the feedlot area and in the area from which the cattle originated. The vaccines used and the vaccination schedule should be based on the expected incidence of the disease, the cost of the disease when it is seen, the cost of the preventive procedure (vaccine plus labor), the field efficacy of the vaccine, and other available control procedures.

Nutritional Advice

Feedlots frequently consult a qualified nutritionist to assist in the formulation of cost-effective diets. The veterinarian should communicate with the nutritionist regarding the composition of the diets and any changes being planned. Most of the emphasis in feedlot nutrition has been on the development of cost-effective diets that support an optimal growth rate without any deleterious effects. Considerable information is available on the nutrient requirements for feedlot cattle and on the feeds and feeding systems used. (Also see Cattle.)

Nutritional deficiency diseases are uncommon in feedlot cattle, because cattle usually receive a diet that contains the nutrients required for maintenance and promotion of rapid growth. Diets prepared according to published standards should meet all the requirements under most conditions. Specific nutrient deficiencies are extremely rare; however, such a situation may be seen in a small farm feedlot that prepares its own diet with little or no attention to the necessity for supplementation of homegrown feeds. Although only a few nutritional diseases may affect a well-managed feedlot, these diseases may cause large economic losses when they develop. They include carbohydrate engorgement (grain overload or d-lactic acidosis), feedlot bloat or ruminal tympany, and feeding errors (ie, accidental incorporation of an excessive amount of a feed additive, such as monensin or urea, or sudden unintended changes in the ingredient composition of the diet).

Disease Epidemics

In spite of good management, unexpected disease epidemics are seen in feedlot cattle. When feeding accidents occur, many animals can be affected suddenly, ie, within 1–2 days. In outbreaks of acute infectious diseases, such as infectious bovine rhinotracheitis, pneumonic pasteurellosis, or Histophilus meningoencephalitis, the first few cases are followed by a steady increase in the morbidity rate for several days and then a decline as the outbreak subsides 10–14 days after the index case.

In some cases, the diagnosis may be obvious (eg, carbohydrate engorgement caused by a feeding error). In other cases (eg, infectious diseases of the respiratory tract), the diagnosis may not be readily obvious, and a detailed epidemiologic, clinical, and laboratory investigation may be required. A complete investigation may require specialists from several disciplines. Every effort should be made to determine the specific source of the disease. The investigation should include a general description of the problem, a complete history of the disease outbreak (including details and date of index case, total number of sick animals, treatments, case fatality rate, population mortality rate, and vaccination history), and clinical examination of several affected animals (with appropriate samples) as well as necropsies. After the diagnosis is determined, the rationale for treatment is outlined. When outbreaks of infectious disease are encountered, the intensity of surveillance must be increased to detect new cases in the early stages of disease when response to treatment is usually good.

All of the details of the outbreak should be listed in chronologic order and then analyzed. Correlations can be made between exposure factors and the development of new cases during the course of the outbreak. Often, epidemiologic determinants that explain disease occurrence can be identified and the information used to control future episodes. A detailed report of the outbreak, outlining the conclusion and recommendations, should be prepared by the veterinarian and nutritionist and submitted to the owner.

Last full review/revision April 2014 by W. Mark Hilton, DVM, DABVP

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