TOPICS IN NUTRITIONAL MANAGEMENT OF FEEDLOT CATTLE

Transcription

1 TOPICS IN NUTRITIONAL MANAGEMENT OF FEEDLOT CATTLE Preface Larry C. Hollis and KC Olson xi Interaction Between Consulting Veterinarians and Nutritionists in the Feedlot 171 Robert A. Smith and Larry C. Hollis The consulting nutritionist and veterinarian typically spend more time at the feedyard than other advisors. Both bring unique credentials to the client, but at the same time much of their training has common roots. Their goal should be to provide the best possible advice and service to the feedlot for the benefit of the cattle, the cattle owners, and ultimately the consumer. This is best accomplished by maintaining open communication and a spirit of teamwork. The two professions have a profound positive impact on animal health, feeding performance, cattle well being, beef quality, and consumer acceptance. When accomplished, everyone benefits. Integrating Lifetime Nutrition: From Cow/Calf to Stocker to Feedlot 177 Glenn C. Duff Given the diversity of nutritional background of beef cattle, the more information the nutritionist can acquire, the better the nutritional management programs during the finishing period can be developed. Some factors that should be accounted for include weaning status and previous growing treatments. Working cattle up on feed and bunk management continue to be a challenge for nutritional consultants. Use of anabolic implants continues to be one of the most effective management programs; however carcass quality may be affected with some implants. Receiving Cattle Nutrition 193 R.L. Preston Depressed feed intake is the major nutritional problem in newly received feeder cattle. This article draws on findings from receiving VOLUME 23 Æ NUMBER 2 Æ JULY 2007 v

2 experiments to offer recommendations on common matters of debate. These include the initial use of feed versus water; appropriate types of feed; the dietary roles of concentrate, protein, and other nutrients; the use of medication; and strategies for lactic acid adaptation and prevention of acidosis. Processing of Corn and Sorghum for Feedlot Cattle 207 Chris J. Richards and Britt Hicks Approximately 75% to 80% of expenses involved in cattle feeding in commercial feedlots are feed costs. Grains are used in feedlot diets to improve the performance and efficiency of feedlot cattle by increasing the energy density of diets. Grains for these diets are commonly processed for various reasons, including improving palatability, altering particle size, increasing digestibility, altering the rate, site, and extent of digestion, and facilitating preservation or storage. Altering the rate, site, and extent of digestion in turn can alter cattle performance. This article focuses on processing methods common to feedlots and the primary grains fed, corn and grain sorghum. Feeding Corn Milling Byproducts to Feedlot Cattle 223 Terry J. Klopfenstein, Galen E. Erickson, and Virgil R. Bremer Corn milling byproducts are expected to increase dramatically in supply as the ethanol industry expands. Distillers grains, corn gluten feed, or a combination of both byproducts offer many feeding options when included in feedlot rations. These byproduct feeds may effectively improve cattle performance and operation profitability. When these byproducts are fed in feedlot diets, adjustments to grain processing method and roughage level may improve cattle performance. Innovative storage methods for wet byproducts and the use of dried byproducts offer small operations flexibility when using byproducts. As new byproducts are developed by ethanol plants, they should be evaluated with performance data to determine their product-specific feeding values. Feed Value of Supplemental Fats Used in Feedlot Cattle Diets 247 Richard Avery Zinn and Alejandro Plascencia Jorquera The inclusion of supplemental fats in growing-finishing diets for feedlot cattle also improves diet condition. Quality factors that may influence the feeding value of fat include the source of fat; moisture, impurities, and unsaponifiables; free fatty acid concentration; degree of saturation or titer; and rancidity (peroxide value). The net energy value of fat declines linearly with an increasing level of supplementation because of constraints on postruminal fatty acid digestion. The authors recommend that receiving diets not contain more than 2% supplemental fat. Little evidence vi

3 suggests that the feeding value of fat is different for Holsteins than for conventional beef breeds. Fat supplementation is not consistent in its effect on intramuscular fat distribution (marbling), longissimus (rib eye) area, and fat thickness, but can be expected to increase dressing percentage and kidney, pelvic, and heart fat percentage. Preparing Holstein Steer Calves for the Feedlot 269 John Maas and Peter H. Robinson It is increasingly common to raise Holstein steer calves for entry to feedlot production systems rather than more traditional milk-fed veal production systems. Providing adequate nutritional support for the maintenance and growth of Holstein calves is essential in preparing them for a commercial feedlot environment. In this article, the dietary requirements of preruminant calves are reviewed and examples of evaluating milk diets for Holstein calves are detailed. The importance of the transition between milk feeding and grain-forage diets is discussed. Aspects of disease prevention, such as coccidiosis control and colostrum feeding, are also discussed. The reader will gain practical tools to use in preventive medicine programs involving Holstein steers being prepared for commercial feedlots. Feeding Holstein Steers from Start to Finish 281 Glenn C. Duff and Casey P. McMurphy Holstein beef has become a significant segment of the feedlot industry. Holstein steers typically enter the feedlot at a lighter body weight, require more pen space per animal, and are in the feedlot for longer periods of time than beef breeds. The only real differences in carcass characteristics are the lower dressing percentage and the smaller rib eye area, which can be increased with anabolic implants and the use of b-agonists. Holsteins are typically fed higher roughage concentrations. Fat concentrations can also be increased to offset the lower energy diets. Protein requirements do not appear to be different from beef cattle, although Holstein steers weighing from 300 to 700 lb should be fed plant protein sources (eg, soybean meal). Regulation of Drugs Used in Feedlot Diets 299 Virginia R. Fajt Diets fed to feedlot cattle typically contain nutritional ingredients along with other substances intended for various purposes, including growth promotion and disease prevention and control. Questions often arise as to the nature of those feed additives, whether and how they are regulated, and what is legal or illegal. In this article, the author discusses regulations pertinent to the use of drugs in feedlot diets. The article includes a discussion of what a drug is, how drugs are approved in the United States, what uses of drugs vii

4 in feedlot diets are legal or illegal, and what is on the horizon for future drug regulations. Growth-Promotant Implants: Managing the Tools 309 Chris Reinhardt Great contemplation, conversation, and controversy have surrounded the use of growth-promotant implants since their inception in the 1950s. Since the very beginning, the purpose of growth promotants has been to enhance production efficiency, reduce the cost of production, and improve profitability. Changes in our understanding of the physiologic mechanisms involved in growth promotion have not altered this fundamental purpose. With enhanced knowledge of the impact of various compounds and doses on different classes of animals, and with the introduction of numerous products providing those compounds and doses, planning implant programs has become difficult. However, the net return from a well-designed implant program may mean the difference between profit and loss on a given set of cattle. Alterations in the Physiology of Growth of Cattle with Growth-Enhancing Compounds 321 Bradley J. Johnson and Ki Yong Chung Commonly used growth promotants such as steroidal implants and b-adrenergic agonists have recently been implicated in the reduction of marbling scores in beef cattle. These compounds are effective at improving lean tissue deposition in cattle, thus significantly improving feed efficiency. This article discusses skeletal muscle growth and development in cattle, the process of transdifferentiation between two cell types, and how growth promotants may push a nondifferentiated cell to become a certain lineage of cells. Increased understanding of how these agents affect cellular aspects of growth and development of skeletal muscle and adipose tissue will allow cattle feeders, consultants, and researchers to instigate intervention strategies to ameliorate the reduced marbling scores. Successful strategies would allow maximal lean tissue growth and result in carcasses with optimal quality. Acidosis in Feedlot Cattle 333 T.G. Nagaraja and Kelly F. Lechtenberg Mortality from digestive diseases in feedlot cattle is second only to that from respiratory diseases. Acidosis is a major digestive disorder and is likely to continue because of ongoing attempts to improve the efficiency of beef production by feeding more grain and less roughage. Subacute acidosis is the most prevalent form of acidosis in feedlots but is difficult to diagnose because of the absence of overt clinical signs. Control of acidosis is achieved largely by sound nutritional management. No single strategy or solution exists; however, an effective management strategy should viii

5 factor in dietary formulation, a consistent feeding program, prudent bunk management, use of nonstarch by-products, and feed additives to minimize pen-to-pen and animal-to-animal variations in feed intake. Liver Abscesses in Feedlot Cattle 351 T.G. Nagaraja and Kelly F. Lechtenberg Liver abscesses in feedlot cattle result from aggressive grain-feeding programs and are influenced by a number of dietary and management factors. They have a major economic impact on the feedlot industry because of liver condemnation and reduced animal performance and carcass yield. Ruminal lesions resulting from acidosis usually are accepted as the predisposing factors. Generally, control of liver abscesses in feedlot cattle has depended on the use of tylosin, which reduces abscess incidence by 40% to 70%. However, new methods and products for liver abscess control are needed. Corn milling by-products that are less fermentable may aide in the quest for cattle production techniques that lead to lower usage of antimicrobials. A vaccine is also commercially available. Index 371 ix