Feedlot

From the fields and feedlots, food is transported to facilities, where more fossil fuel, more water, more chemicals, and electricity are used to process and package the food.

From: Environmental Nutrition , 2019

Overview of cattle production systems

Marcia I. Endres , Karen Schwartzkopf-Genswein , in Advances in Cattle Welfare, 2018

1.3.3 Feedlot production system

The feedlot sector represents an intensive production system with the goal of growing and or fattening cattle until they reach slaughter weight. The feedlot sector can be further divided into growing (backgrounding) and finishing (fattening) phases. In North America the backgrounding phase (typically the first 90 days after arrival for feedlot calves) focuses on feeding high-forage/low-grain rations with the goal of maximizing growth and minimizing fat deposition. Welfare issues in the backgrounding phase can include injuries during handling associated with revaccination and implant protocols, as well as increased morbidity due to the stressors related to transition from the ranch to the feedlot indicated earlier. The finishing phase (typically the last 100 days after backgrounding) focuses on feeding high-grain/low-forage rations to backgrounded calves or yearlings until they reach a prescribed finish (fat cover) before marketing for slaughter. Welfare issues in the fattening phase are predominantly related to the feeding and include free gas bloat, acidosis, liver abscesses, and laminitis, all of which are associated with high concentrate feeding typical in North America and Europe. Some feedlots focus solely on either backgrounding or finishing, however, it is not uncommon to have one feedlot feed calves from growth to finish. Some ranches have their own feedlot facilities where cattle are bred and finished for slaughter by the same producer, but this is less common. Although pasture finishing is the most predominant system in Brazil, a growing percentage of cattle are being finished in feedlots (approximately the last 70 days before slaughter) where they are fed a diet with higher forage content than North American cattle ( Millen et al., 2009).

Both the background and finishing (fattening) phases of the feedlot sector use the same housing and facilities. The phases are defined more by the type of cattle and how they are fed rather than the way they are housed. Consequently, the following description will cover the environmental/housing conditions of both and will be referred to as 'feedlot production' in this section.

Feedlot production represents an intensive confinement system that has high input costs (compared with suckler calf and stocker production) associated with extensive infrastructure, feeding, medical, and labor costs. There are two types of feedlots, outdoor and indoor. The outdoor feedlot is suited for drier climates (Fig. 1.25). In addition to animal comfort, indoor facilities also function to keep feed and bedding dry. It is for these reasons that in wetter climates cattle are housed indoors or in partially enclosed shelters or barns. The main difference between indoor and outdoor lots is that indoor feedlots are much smaller and hold fewer cattle per pen but at higher stocking density. They usually have slatted floors so the manure can to fall through to a holding pit (Fig. 1.26A). The indoor facility, as is implied, has a roof and side walls (solid or curtains) that can be opened when weather is moderate (Fig. 1.26B). With the exception of these features, indoor and outdoor facilities are very similar.

Figure 1.25. Outdoor feedlot facility.

 Source: Photo courtesy of Dr Karen Schwartzkopf-Genswein, Lethbridge, Alberta, Canada.

Figure 1.26. (A) Fully enclosed (indoor) feedlot facility with slatted floors and (B) semi open feedlot facility.

 Source: (A) Photo courtesy of Dr Derek Haley. (B) Photo courtesy of Dr Karen Schwartzkopf-Genswein, Lethbridge, Alberta, Canada.

In temperate climates both indoor and outdoor feedlots typically have barns for handling and processing cattle (known as processing barns). The barns contain pens and handling equipment such as holding pens (Fig. 1.27), a crowd tub and curved or straight chute (Fig. 1.28) that leads to a squeeze chute (Fig. 1.29) where the cattle can be restrained to receive vaccinations or other medical treatments. The barn can be completely or partially closed which is more for the comfort of the feedlot staff than the animals. In tropical climates, barns are not as common and usually only consist of the handling components of the facility such as the crowd pen, chutes, and squeeze chutes. European feedlots have minimal handling equipment or infrastructure such as central handling alleys which makes handling a welfare issue for both the cattle and the stock attendants.

Figure 1.27. Example of a central handling alley with holding pens.

 Source: Photo courtesy of Dr Karen Schwartzkopf-Genswein, Lethbridge, Alberta, Canada.

Figure 1.28. An example of a crowd tub and curved chute within a processing barn.

 Source: Photo courtesy of Dr Karen Schwartzkopf-Genswein, Lethbridge, Alberta, Canada.

Figure 1.29. A squeeze chute used to restrain cattle for the delivery of vaccinations or medical treatments.

 Source: Photo courtesy of Dr Karen Schwartzkopf-Genswein, Lethbridge, Alberta, Canada.

A typical outdoor feedlot has perimeter as well as internal fencing. In temperate climates, porosity fencing is constructed to reduce the effects of wind chill (Fig. 1.30). Heat stress can be more severe in feedlot environments where cattle may have little access to shade, are in close proximity to other cattle and have high heat loads associated with rumen fermentation. It is for these reasons that heat stress abatement strategies are used in hotter regions and include sprinklers or shade structures within the pens. For example, every year hundreds of cattle die during heat waves in the USA where daily and evening temperatures are similar and cattle have no way of dissipating their heat load.

Figure 1.30. Outdoor feedlot with perimeter and porosity fencing.

 Source: Photo courtesy of Dr Karen Schwartzkopf-Genswein, Lethbridge, Alberta, Canada.

All feedlots have feed troughs/bunks lined along one side of the pen where feed can be delivered usually by trucks or tractors (Fig. 1.31). Bunks keep feed from being scattered and minimize contamination from manure and mud. Feed bunks can be made of wood, metal or concrete and often have a concrete apron in front of them so that cattle can stand on a level surface while feeding (Fig. 1.31). Each pen contains a water trough that is usually automatic and a raised dirt mound or sloped area where straw or wood chip bedding can be spread. The mound or sloped area supplies an area where cattle can lie down particularly when the pens get excessively muddy during rainy or snow thaw periods (Fig. 1.32). Depending on the size of the pen, cattle are housed in groups ranging in size from 50 to 350 head. Pens are graded to a slope that allows drainage. In both indoor and outdoor systems welfare may be compromised as a result of muddy pen conditions. In comparison to pasture conditions there is an increased incidence of lameness and injury because mud creates slippery conditions and facilitates spread of infectious claw-related disease such as foot rot or digital dermatitis (Stokka et al., 2001). There is limited research on beef cattle lameness in feedlots with concrete or slatted floors. However, claw health appears better for beef cattle kept in straw yards or deep litter rather than on slatted floors (Tessitore et al., 2009). Mud also makes locomotion more difficult and results in greater energy expenditure and can also affect heat loss. There is also evidence that cattle lying behavior may be affected by mud. Overall movement may be more limited within a feedlot pen versus on pasture as a result of higher stocking density and available space per animal as well as the effects of excessive mud which is known to limit ambulation within the pen.

Figure 1.31. Feed bunks with concrete apron in an outdoor feedlot.

 Source: Photo courtesy of Dr Karen Schwartzkopf-Genswein, Lethbridge, Alberta, Canada.

Figure 1.32. Dirt mounds or slopped areas are used to provide drier areas in outdoor feedlots.

 Source: Photo courtesy of Dr Karen Schwartzkopf-Genswein, Lethbridge, Alberta, Canada.

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ENERGY REQUIREMENTS OF ALTERNATIVE BEEF PRODUCTION SYSTEMS IN COLORADO

Gerald M. Ward , ... Terence P. Yorks , in Agriculture and Energy, 1977

Feedlot model

Feedlots are totally dependent upon harvested feed ingredients from the crop production model. Three rations were considered. The daily feed ingredients in the rations on a dry-matter basis for a typical 825 lb average weight of beef animal are given in Table 4. The expected average daily gains are 3.0 lb/day for rations 1 and 2, and only 2.1 lb/day for ration 3.

TABLE 4. Rations for Feedlot Cattle. (Lb/head/day, for beef cattle of 825 lb average weight.)

Ingredient Ration 1 Ration 2 Ration 3
Corn grain 18.0 – –
Flaked corn – 16.0 –
Beet pulp pellets – 2.0 –
Soybean meal 1.0 1.0 1.0
Corn silage (dry wt) 2.4 1.8 12.0
Alfalfa hay – – 2.0

Three basic weight intervals for beef production were considered in the model. Calves produced by the rangeland models weigh 440 lb. The backgrounding phase feeds the cattle until a 715 lb weight. The final finishing phase raises the weight to 1100 lb. The above daily rations are converted into total rations needed to raise the weight from 440 to 715 lb and from 715 to 1100 lb. National Research Council guidelines [25] are used in the conversion. Feed processing varies with the ration so that separate activities are available for grinding and flaking operations.

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Nutrition, feeding and management of beef cattle in intensive and extensive production systems

Tim A. McAllister , ... Gabriel Ribeiro , in Animal Agriculture, 2020

Finishing

Finishing feedlots are larger than backgrounding feedlots and usually house >10,000 head of cattle, with 150–200 animals per pen ( Fig. 5.1). Unlike backgrounding diets, finishing feedlot diets contain high amounts of concentrate feeds (>70%) and are designed to increase both subcutaneous and intramuscular (marbling) fat. To avoid digestive disturbances, like ruminal acidosis and bloat, calves must be carefully transitioned from forage-based to concentrate-based diets during finishing. This process usually requires a series of 2–4 diets, where the amount of concentrate feeds is gradually increased over a period of 2–4   weeks. Reducing the duration of adaptation to less than two weeks can impair the growth performance of cattle. 26 This transition period is the time when cattle are at greatest risk of developing acidosis or bloat. When cattle first arrive at finishing feedlots they are typically provided with access to a total mixed ration (TMR) receiving diet, consisting primarily of forage and a smaller proportion of concentrate. Initially, the feed intake of newly arrived cattle can be very low and some cattle may not consume feed. 27 The introduction of the final high-concentrate diet is typically withheld until all cattle have settled into confinement and exhibit consistent and stable feed intake.

Abrupt diet change from forage to grain has been reported by many researchers to result in ruminal acidosis. 7 Even when dietary concentrate is increased using a step-up approach, increases in concentrate may cause acidosis. On the first day of each transition, low ruminal pH values are common and Klopfenstein et al. 28 concluded that during adaptation, it is likely that all cattle experience at least some mild level of acidosis. In contrast, Bevans et al. 29 accomplished this same objective using a single diet and encountered only a few cases of clinical acidosis. Others have proposed that subclinical acidosis is mainly caused by the high ruminal concentrations of volatile fatty acids arising from the fermentation of starch. 30 Low ruminal pH also reduces the diversity of both bacteria and protozoa within the rumen microbiome, 31,32 an outcome that is also associated with a reduction in fiber digestibility. 33 A shorter adaptation period to grain-based diets tends to be associated with greater variability in pH among individuals as opposed to an absolute pH decline. 29 Under these conditions a small proportion of the herd, typically < 2% may develop clinical acidosis. The risk of clinical acidosis and the occurrence of subclinical acidosis can be reduced by increasing the proportion or lowering the quality of the forage in the diet. 34 This serves to reduce the rate of ruminal volatile fatty acid production and stimulates rumination and the production of saliva, which contains sodium bicarbonate that buffers ruminal pH. Skillful feeding management can minimize both the occurrence and severity of acidosis, but as long as feedlot cattle are finished on high-grain diets, acidosis will pose a health risk. A detailed understanding of clinical acidosis has been hampered by its low rate of occurrence and the multitude of factors that contribute to the disease (Fig. 5.2).

Fig. 5.2. Possible factors and interrelationships affecting acidosis in feedlot cattle. Solid arrows indicate relationships known to exist with a high degree of confidence, whereas dotted arrows represent putative relationships.

 Adapted from Galyean ML, Eng KS. Application of research findings and summary of research needs - bud britton memorial symposium on metabolic disorders of feedlot cattle. J Anim Sci. 1998;76:323–327.

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Feedlot Vaccination Protocols

Janey L. Gordon , Daniel U. Thomson , in Food Animal Practice (Fifth Edition), 2009

CLOSTRIDIAL DISEASES

Clostridial disease in feedlots may be rare because of the extensive use of clostridial vaccines in cattle before entering the feedlot. However, clostridial diseases that can found in the feedlot include malignant edema (Clostridium septicum), blackleg (Clostridium chauvoei), black disease (Clostridium novyi type B), redwater disease (C. novyi type D), enterotoxemia (C. perfringens type D), bacillary hemoglobinuria (Clostridium hemolyticum), and tetanus (Clostridium tetani). 50,51 Some clostridial vaccinations have been associated with injection-site lesions, so concerns have developed for prudent use of these vaccines. Despite the potential for injection-site lesions, the 1994 National Animal Health Monitoring System report indicated that 34.4% of feedlots with fewer than 1000 head used clostridial vaccines, whereas 91% of larger feedlots vaccinated against one or more clostridial agents. To respond to the topic on injection-site lesions with clostridial vaccines, the National Cattlemen's Beef Association's Beef Quality Assurance task force released recommendations, which include the use of subcutaneous injections whenever possible. Furthermore, after the primary immunization with clostridial bacterins, repeat or multiple injections should be discontinued, especially late in the feeding period.

A common consensus among feedlot veterinarians is to administer a clostridial vaccine to calves on arrival. However, it is probably not advantageous to administer more than one clostridial vaccine after arrival to the feedlot. Several studies have shown detrimental effects on feedlot performance after a booster of clostridial vaccine. One such study reported a 20% decrease in feed consumption in response to a second vaccination with a multivalent vaccine. 52 Additionally, another study indicated there was no effect on the incidence of sudden death syndrome after a second vaccination. 19

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Biotechnological Approaches to Improve Sustainable Milk and Meat Yield in Bovines

Cristina Castillo , ... Joaquín Hernández , in Reference Module in Food Science, 2017

N-Derivatives Control

Reactive nitrogen from feed yards could negatively influence the air and water quality in the event of volatilization of ammonia (NH3) and nitrous oxide (N2O), and leaching and runoff of nitrate (NO3 −), or other forms of organic and inorganic N. The review performed by Waldrip et al. (2015a) offers current evaluation methods to mitigate losses of N from feed yards, identifying the gaps that require further research. According to this information, there are key factors to study: feed yard manure management and cattle diet.

•

Nitrogen-balance studies showed that only about 15% of the N flow through a feed yard remains in animal tissue (average of 25   g animal day-1), and that most of the N (44%) was lost to the atmosphere or as runoff, whereas only 41% was removed with harvested manure.

•

Dietary concentration of proteins and its ruminal degradation were the primary factors affecting the quantity and route of excretion (urine vs. feces) of N by beef cattle.

In relation to ammonia (NH3) other review of Waldrip et al. (2015b) reports the state of the science concerning feed yard NH3 and evaluate methods to mitigate their losses. Briefly, the review shows the following:

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Up to 90% of feed yard NH3 originates from urine deposited in animal pens, but the magnitude of this loss depends on both weather and management practices

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Feed yard NH3 emissions are higher in summer than winter, largely because of increased temperature

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Both urea excretion and subsequent NH3 emission increased with dietary protein concentration

The authors describe that managing cattle diets to meet, but not exceed, metabolic protein requirements is the most practical way to reduce N losses; however, diets must be changed carefully to avoid unintended negative consequences on animal production. Other possible mitigation approaches are (1) dietary manipulation to decrease N excretion, (2) inhibition of urea hydrolysis, and (3) capture of ionic ammonium in manure with pen-surface amendments (e.g., urease inhibitors, alum, and zeolites).

To end this section, it is clear that manure management systems that prevent pollution and minimize fugitive CH4 emissions are becoming increasingly attractive. Anaerobic digestion results in the production of biogas that can be used as a renewable source of electricity on-farm or sold to the distribution grid. Anaerobic digestion can also reduce GHG emissions, odors, and water contamination. Digested manure solids can be recycled on-farm as bedding material, thus decreasing operational expenses (Arikan et al., 2015).

On the other hand, nanotechnology-enabled catalysts will play a critical role in efficient and cost effective bioconversion and fuel cell for electricity production as well as enabling efficient energy storage, which will greatly facilitate and benefit the development of distributed energy supplies, especially in rural communities where infrastructure is lacking. Such an approach may result in the elimination of the need for system-wide electricity grids, hence accelerating rural development and improving productivity, business and living environment, and will be especially beneficial to developing countries (Thornton, 2010; Chen and Yada, 2011).

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PRESLAUGHTER HANDLING | Design of Stockyards, Lairages, Corrals, Races, Chutes, and Loading Ramps

T. Grandin , in Encyclopedia of Meat Sciences (Second Edition), 2014

Layout of Stockyards

The best stockyards have one-way traffic through the yards. Animals enter through one alley and leave to go to the stunner through an alley that is at the other end of the pen. Pens can be laid out either straight or on an angle (herringbone). Angled pens work well but they must be laid out correctly. The correct angle for all species is pens on a 60–80° angle (Figure 3). Never use a 45° angle. Animals might get stuck in the corners. To further eliminate corners, gates can be built that are longer than the width of the alley so that they open on an angle. The recommended alley and gate lengths are:

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Cattle – 10   ft (3   m) alley with 12   ft (3.5   m) gates

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Pigs and sheep – 8   ft (2.5   m) alley with 10   ft (3   m) gates

Some plants use narrower alleys for pigs. When narrow alleys are used, pigs should be moved in much smaller groups of 10 or less.

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Growth curves and growth patterns

Steven M. Lonergan , ... Dennis N. Marple , in The Science of Animal Growth and Meat Technology (Second Edition), 2019

Feedlot Management Concepts for the Production and Marketing Plan

As cattle in the feedlot approach harvest time, real-time ultrasound measurements can be used to help the feedlot management make good marketing decisions. The three criteria used in the study to establish the genetic base for selection of quality cattle for the feedlots should be used in the decision process on when to send the feedlot cattle to the packer for the harvest process. The three criteria are as follows:

1.

Live weight: When cattle reach a weight on the growth curve where average daily gains start to slow, it is a good time to use the real-time ultrasound scans to estimate the carcass traits. This is usually 30 days or about 100 pounds before expected harvest. The live weight of the cattle should be obtained at this time. When the live weight is obtained, the carcass weight of the cattle can be estimated by multiplying the live weight by the estimated dressing percentage (61.5%–63.5%). Marketing cattle at an acceptable weight range is important for obtaining a good market price. Acceptable carcass weights usually range from 600 to 950 pounds. Individual packing companies may deviate slightly from this range.

2.

Subcutaneous fat cover: When the live weights of the cattle are obtained, real-time ultrasound measurements for the subcutaneous fat cover should be obtained at the 12th–13th rib area. The fat thickness is a major factor for the determination of the USDA Yield grade. The relationships are presented in Table 6.2. This information can be used by the feedlot management on when to market the cattle to obtain a good market price and not overfeed the cattle. Feeding cattle to a weight where excess waste fat is deposited not only reduces the market value but also reduces the feed efficiency of the cattle in the feedlot.

Table 6.2. Relationship between fat thickness at the 12th rib and USDA preliminary yield grade for cattle

Fat cover (in.) Preliminary Yield grade
0.2 2.5
0.4 3.0
0.6 3.5
0.8 4.0
3.

Percent intramuscular fat: The intramuscular fat percentage should also be determined by real-time ultrasound when the cattle are weighed. The intramuscular fat percentage is determined at the 12th–13th rib of the live cattle. Intramuscular fat percentage in the live animal can be related to the degree of marbling in the carcass as cattle grow in the feedlot. An example is shown in Fig. 6.31, Example A. Feedlot management can use this information as a guide on how long to feed cattle to obtain the most profitable return on investments based on the original feeder cattle prices as well as feed costs.

Marbling score is the primary determinant for the quality (Prime, Choice, Select) grades of beef carcasses, and a major price difference often exists between Select and Choice grades in most markets. Therefore the feedlot managers will balance the value effect of weight, subcutaneous fat thickness (Yield grade Value), and intramuscular fat percentage (Quality grade Value) with feed efficiency of the cattle when decisions are made to market the cattle for harvest to the packer.

The feedlot managers have several options to consider when they market cattle. Marketing cattle on a live weight basis is the old method that has been in place for years. The purchase price (bid) for the cattle may be from a packer buyer or from a price determined at the sale barn. The price is for the live weight and is usually expressed as the dollars per hundred weight. For this option, carcass information is not usually reported back to the owner of the cattle.

Another option for the feedlot managers is to sell the cattle for the value of the hot carcass weight. This is often called selling in the beef by the industry. It is used when dressing percentage is difficult to evaluate, such as muddy conditions of the hide of cattle. Usually this option includes the value based on a truckload of cattle. In this system, the producer or feedlot owner is responsible for the trim loss of the carcass that occurs before the hot carcass weight is obtained. In this marketing option, the packer can obtain the carcass traits such as carcass grade, marbling, and subcutaneous fat and return the information to the feedlot management or owner of the cattle.

A third marketing option is the Grid method. When cattle are sold on the grid option, the packer provides a price for each carcass and provides the 12th–13th rib fat thickness, rib-eye area, and degree of marbling. The carcass Yield grades and Quality grades are also provided.

An example of a Grid Marketing Program that promotes higher carcass prices for cattle that have a Quality grade of Choice and a Yield grade of 1 or 2 will be described later. Only a limited number of cattle have these traits. Therefore a Grid Marketing Program for Choice Quality grades and Yield grades of 1 or 2 can be used by the industry for selection programs to improve the genetic base and strengthen the marketing programs for cattle with a low amount of subcutaneous fat and a high amount of marbling. An example for cattle with these traits is shown in Fig. 6.31 (Example B) when they enter the feedlot until harvest. It is important to market these cattle when they grade Choice and before they deposit more than 0.3   in. of fat at the 12th and 13th rib.

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Investigating Feedlot Respiratory Disease Outbreaks

Larry C. Hollis , in Food Animal Practice (Fifth Edition), 2009

GATHER THE PERTINENT HISTORY

The initial contact by feedlot personnel will describe the reason for their concern. As information about the cattle and situation is put together, a mental picture will begin to develop. Questions should move from general to specific. The normal starting point is a series of general questions, usually starting with asking about the region of the country where the cattle originated. The experienced feedlot veterinarian knows that a semiload of cattle purchased through an order buyer in a particular state may be made up of cattle originating from up to 40 different farms located in 10 different states. The "origin" just happens to be the home base for the order buyer who assembled the load. Gathering this type of history helps the veterinarian determine that the cattle may have come from an area where cattle are commonly mismanaged or undermanaged, a mineral-deficient area, an area where tall fescue frequently creates a toxicity problem, or where internal or external parasitism may be a major contributing factor.

Specific history of the cattle should be obtained. What is the age, sex, quality, and origin of the cattle? How were the cattle purchased or supplied to the feedlot—ranch/farm of origin, video auction, local auction barn, stocker or backgrounding operation, order buyer? If cattle were from multiple origins, how long did it take to put the load together? From which states were cattle assembled? Were cattle fresh at the time of purchase? Were cattle preconditioned? What products, procedures, and timing were included in any preconditioning program? Was anything requested to be done to cattle at an order buyer facility (e.g., castrated, dehorned, vaccinated, mass medicated, individuals treated for illness)? Were any things done that were not requested or anticipated before shipment? Were the trucks clean before the cattle were loaded? When did the trucks load up and leave for the feedlot? What was the distance between the origin and the feedlot? How long were the trucks en route? Did the trucks encounter any delays? Answers to these questions help develop the mental picture further and provide additional insight into the overall situation.

Arrival history at the feedlot should then be obtained. What time of day/night did the trucks arrive? Did a qualified person watch the cattle unload from the trucks? Did the cattle match the description of the order from a health status and freshness appearance, as well as number, sex, quality, etc.? Were there dead cattle on the truck or cattle that were obviously sick as they unloaded from the truck? What did the cattle do when they were placed in the receiving pen—explore the pen, search for feed and water, or lay down and rest? Did the cattle appear dehydrated? Were the cattle bawling? How much did the cattle shrink from payweight at the point of origin to the inweight at the feedlot? Were answers based on memory, or were these items routinely recorded for each set of cattle received at the feedlot? Again, answers to these questions provide additional insight.

Processing history should be obtained next. How long were the cattle rested between arrival at the feedlot and processing? Were backtags removed to see if the amount of hair retained on the backtag matched the amount of hair missing from the spot where the backtag was removed? Which vaccines were administered and what procedures were conducted during processing? How were the vaccines handled from the time of purchase until the actual time of administration to the animals? Were observations made for sick cattle before and during processing? Were temperatures taken as animals were being processed? Were any delays encountered during processing? Were cattle mass medicated and, if so, with what product and dose? Has the processing crew experienced problems in the past? Were new personnel working on the processing crew the day the problem cattle were processed? Were serial numbers recorded for products administered, as well as the name of the individual administering each product? Were answers based on memory, or were these items routinely recorded for each set of cattle processed at the feedlot? All of these answers lead to more insight.

Transitioning to feed history should be obtained. What is the general history of this feedlot's ability to mix rations properly and deliver the correct ration to the correct pen of cattle on a timely basis? Were there any problems getting the cattle started on feed? How does this feedlot transition cattle from starting ration to finishing ration? Which ration step were the cattle on when the respiratory outbreak started? If the problem occurred later in the feeding period, were there any problems getting the cattle to step up through the intermediate rations to the top ration? Were there any feed-related problems at any time before the time the respiratory outbreak occurred?

Time and location history should be obtained. Is there only a single pen or several groups of cattle affected? Is it a generalized problem or localized to a specific area within the feedlot? Is there a pattern in the age, sex, or arrival time of affected cattle? Is the affected section of the feedlot served by a specific treatment facility? Did the problem arise following a weekend, holiday, or major social event when feedlot employees might have been preoccupied? Are there new pen riders or new members of the treatment crew? How well do they know their jobs? Has the veterinarian observed them doing their jobs?

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General Systemic States

In Veterinary Medicine (Eleventh Edition), 2017

Control

Shade alone is the most important factor in maintaining the comfort of livestock and preventing heat stress. Shade reduces the heat gain from solar radiation and can be provided by trees or artificially by roofs or shades made from cloth or artificial material. Shades should be placed over feed and where the producer wants the animals to spend their time. The efficiency of metal shades can be increased by painting metal shades white on the topside and black on the underside. A north–south orientation will permit drying under the shades as the shaded area moves throughout the day; this may be helpful in decreasing the incidence of coliform mastitis if sprinklers are used under the shades and cattle prefer to lie under the shades than in freestalls.

In dairy and feedlot cattle, the following measures should be taken to manage heat stress:

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Provide cool clean water and plenty of trough space for drinking.

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Use shades and intermittent sprinkler systems (wet time of 1–2 min with an adequate dry off time of 20–30 min); continuous application of water increases the local humidity and decreases the effectiveness of evaporative cooling.

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Enhance airflow by fans or by providing mounds for cattle to stand on.

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Adjust rations and feed a larger percentage of the ration in the evening when it is cooler.

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Minimize handling during periods of greatest heat stress.

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Select cattle based on breed and coat characteristics, and house the most susceptible cattle (heavy, black) on east-sloping lots with the most shade; genetic studies have identified genes associated with resistance to heat stress in dairy cattle. 1,6

In exercising horses, periodic rests in the shade with fans and water sprinklers and maintaining a normal hydration status can be very helpful in preventing heat stress. Monitoring the heart rate is a useful and practical method of assessing the degree of heat stress in horses, because heart rates remain elevated for a longer period of time in horses undergoing heat stress.

If animals have to be confined under conditions of high temperatures and humidity, the use of tranquilizing drugs has been recommended to reduce unnecessary activity. However, care is needed because blood pressure falls and the animals may have difficulty losing heat if the environment is very hot and in some cases may gain heat. Chlorpromazine, for example, has been shown to increase significantly the survival rate of pigs exposed to heat and humidity stress.

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Diseases of the Liver

In Veterinary Medicine (Eleventh Edition), 2017

Treatment

F. necrophorum is susceptible in vitro to β-lactam antibiotics, tetracyclines, macrolides, and lincomycins but is resistant to aminoglycosides and ionophore antibiotics. 2 The apparent sensitivity of this gram-negative pathogen to penicillin and cephalosporins is peculiar even based on its cell wall structure. 2

Liver abscess in feedlot cattle is not clinical and not routinely treated as a clinical disease. In clinical disease associated with liver abscess, prolonged treatment with high doses of antimicrobials is required if therapeutic concentrations are to be achieved at the site of infection. Relapse is common because of incomplete control of the localized infection.

Treatment and Control

Treatment

Procaine penicillin G (44,000 IU/kg IM every 24 h long term) (R-2)

Oxytetracycline (10 mg/kg IM every 24 h or long-acting formulation 20 mg/kg every 72 h long term) (R-2)

Ampicillin trihydrate (10 mg/kg SC or IM every 24 h long term) (R-2)

Control

Tylosin (90 mg/animal PO every 24 h long term) (R-1)

Chlortetracycline (70 mg/animal PO every 24 h long term) (R-1)

Oxytetracycline (75 mg/animal PO every 24 h long term) (R-1)

Virginiamycin (16.5–19.8 mg/kg PO every 24 h long term) (R-1)

Vaccination

Vaccination with Fusobacterium necrophorum leukotoxoid/Trueperella pyogenes bacterin vaccines. (R-1)

IM, intramuscularly; PO, orally; SC, subcutaneously.

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