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Ungulates as Laboratory Animals
Abstract
The term ungulate is used to designate all the large mammals with hooves. The general adaptations of the group include the development of an upright digital gait with most of the ani mal's weight borne on the central one or two digits, reduction of the medial and lateral digits, elongation of the distal por tions of the extremities for running, and, in some cases, modi fication of the digestive tract for a herbivorous diet. The two orders, Perissodactyla and Artiodactyla, appear to have devel oped hooves independently and are not closely related to each other.
The use of ungulates as laboratory animals is becoming in creasingly popular, in part due to the high cost and decreasing availability of other large laboratory species, such as the dog, cat, and nonhuman primates. All personnel using livestock species must understand husbandry and handling techniques so that they appreciate the potential risks of zoonotic diseases and physical injury.
This chapter is an introduction to the ungulates as laboratory animals. Topics to be addressed include examples of research uses of ungulates, procurement and preventive medicine, hus bandry, and facilities. The reader is also referred to the Appen dix for information on normative data, nutrition, housing re quirements, and infectious diseases. The confines of a single chapter exclude thorough discussion of these topics. The refer ences listed at the end of the chapter are recommended for more information.
Order: Perrissodactyla (odd-toed ungulates) This order includes Equidae and other taxonomic families not usually en countered in biomedicai research.
Order: Artiodactyla (even-toed ungulates) Family: Bovidae (the common ruminants: cattle, sheep, goats, antelopes) Species: Capra hircus (domestic goats) Ovis aries (domestic sheep) Bos taurus (domestic cattle) Bos indicus (Zebu cattle) Family: Suidae (swine) Species: Sus scrofa (European wild boar and do mestic swine) Eight other living families are in the order Artiodactyla. The Bovidae represent a specialized group of mammals in terms of both anatomy and physiology. The presence of horns, a highly compartmentalized stomach, the fact that they are ob-DALE L. BROOKS, PHILIP C. TILLMAN, AND STEVEN M. NIEMI ligate herbivores and that as adults they derive all their glucose from gluconeogenesis are indications of their uniqueness.
The Suidae are considered somewhat less specialized. The anatomic and functional similarities between pigs and humans derive from the fact that both retain elements of the "basic" mammalian pattern. These elements include brachydont denti tion, a simple digestive tract, and an omnivorous habit. Swine are the only large omnivores that are readily available to inves tigators in many cases.
Agricultural institutions keep cattle for teaching and research of beef and dairy production and husbandry. Adult cattle are seldom used in basic biomedicai research, although some ge netic anomalies are studied in mature cattle as models of com parable human conditions. These conditions include congenital protoporphyria (Ruth et al., 1977) and GM, gangliosidosis (Donnelly and Sheahan, 1975) . Calves are used in cardiovas cular surgery because the size of their bodies and hearts ap proximates that of humans. In most situations, bovine research subjects are dairy calves, and their management consists of conventional pediatrie husbandry (Bath et ai, 1978) .
Sheep are frequently maintained for reproductive studies. Their large gravid uterus, long gestation period, and localiza tion of the placenta into discreet caruncles make them conve nient animals in which to study the development of the fetus (Kraner and Parshall, 1968) . Sheep are used for thoracic sur gery research, studies of hemostasis, endotoxic shock, and prostaglandin metabolism, to mention a few examples. A ma jor advantage of the sheep as a research animal is the relative ease with which it adapts to confinement (Hecker, 1983) .
Goats are similar in many respects to their close relatives, the sheep, and are used in many similar situations. Because they require no grooming or shearing (except for the Angora) and have large and accessible jugular veins, goats are widely used for production of large quantities of antisera. Congenital hypothyroidism of goats is studied as a model for a similar condì-tion in humans (van Dijk et al., 1979) . Other uses of goats include studies of infectious agents, such as caprine arthri tis/encephalitis virus (Crawford and Adams, 1981) . African pygmy goats are especially suitable for rearing in a research facility (Rogers et ai, 1969) .
The usefulness of swine in biomedicai research arises from the fact that there are many anatomic and physiological sim ilarities between swine and humans. There is close mor phological correlation in the eyes, teeth, kidneys, digestive tract, and skin of swine and humans. Swine have often been used to investigate these systems, especially in surgical stud ies. The pig is a useful model for cardiovascular research, both for surgical manipulation, such as prosthetic heart valves and vascular grafts, and for the study of atherosclerosis, a naturally occurring disease in pigs. Pond and Houpt (1978) have pro vided an excellent review of the utility of swine as biomedicai models.
Newborn swine are an excellent pediatrie model and are the animals of choice for comparative study of human infant nutri tion. Swine develop gastric ulcers under natural conditions, and the incidence is increased by stress. In addition, swine become obese when fed ad libitum, and are used as a model for human obesity.
Familial diseases of swine comparable to human maladies include cutaneous melanoma (Hook et ai, 1979) and malig nant hyperthermia (Nelson and Anderson, 1976) . Another ge netic condition of swine used as a model is Von Willebrand's disease (coagulation factor VIII deficiency) (Bowie and Dodds, 1979) .
Laboratory ungulates may be procured from suppliers of lab oratory animals or from traditional agricultural sources. One should inspect the animal health records of the prospective supplier and perhaps carcasses of freshly slaughtered animals (e.g., pigs and lambs). It is often helpful to consult the attend ing veterinarian for additional information regarding preven tive medicine practices and animal health status. Having a sin gle source of supply (i.e., a farm) often makes it easier to monitor the health status of the incoming animals and to work with the supplier to control any disease problems.
There are major differences between a farm versus a sales yard as a reliable source of healthy laboratory subjects. An animal often experiences greater stress in a sales yard through handling and shipping, in addition to exposure to a larger number of infectious agents. Regardless of source, stress asso ciated with transportation and potential infection must be mini mized prior to arrival at the vivarium. An alternative to pur chasing livestock is to establish and maintain a breeding operation. However, this is too costly in most cases for the needs of the institution or investigator.
An investigator's animal requirements should be carefully and clearly ascertained in writing prior to ordering animals. Purchase orders should always define the number of animals needed, their breed, sex, age, an acceptable body weight range, and any other limitations peculiar to the particular study. On arrival at the facility, the supervisor should always make sure the delivery conforms to the specifications of the purchase order. The particulars of acquisition vary somewhat between species and will be discussed separately.
The potential user of laboratory swine may elect to use either conventional domestic swine or laboratory bred miniature swine. The use of swine is limited by their loud and annoying vocalizing, relative difficulty in handling, size of adults, and suitability of secure housing.
For short-term projects, conventional feeder pigs (8-12 weeks old and weighing 12-24 kg) are often satisfactory. These animals can be restrained with moderate effort and can be conveniently housed in most vivaria using slight modifica tions of housing designed for other large species. Such animals grow rapidly and soon require housing designed specifically for adult swine (Pond and Maner, 1974) . If halothane anesthe sia is to be used, the investigator should beware of breed-asso ciated sensitivity to halothane and resultant malignant hyper thermia. Pigs can be tested for halothane sensitivity in order to detect susceptible animals (Topel et ai, 1975; Pond and Houpt, 1978) .
Miniature pigs bred specifically for research are available from several research institutions and commercial vendors (England, 1968) . Their adult body weight of 70 kg still pres ents some difficulties with restraint and housing, but they may be easier to handle than conventional swine weighing two to three times as much (Earl, 1968) . Miniature swine are pre ferred in many cases involving chronic studies on adult pigs, but their characteristics may not always correlate exactly with those of the conventional breeds.
Gnotobiotic (germfree) pigs are used in studies requiring de fined microflora, including infectious disease research. These animals require complex housing and husbandry procedures (Meyer et ai, 1963; Waxier, 1975) . The advent of gnotobiotic swine has enabled establishment of specific pathogen-free (SPF) herds (Tweihaus and Underdahl, 1975) . These animals require less stringent management than gnotobiotic pigs, but should still be maintained as closed herds or procured from a single source.
The supply of sheep of a particular age, sex, and weight class varies tremendously from season to season, reflecting both the seasonality of the animal's estrous cycle and the agricultural practices of a particular locale. Wethers (castrated males) usu ally go to market as soon as they reach proper size. Therefore, it is difficult to obtain wethers at times of the year when the past year's lamb crop is shipped to market. Investigators re quiring time-dated pregnant animals or a continuous supply of animals of a particular age, sex, and breed must either pur chase well in advance of their needs and hold animals until they are used, breed their own sheep, or contact a supplier attuned to the investigator's needs. Otherwise, lambs will only be available from midwinter to late spring, as determined by geographical region.
While a great number of breeds of sheep are available, the majority of commercial animals are cross-bred and can be broadly grouped into the white-faced/wool types, the blackfaced/meat types, or range lambs that are usually progeny of white-faced ewes and black-faced rams. Researchers per forming vascular surgery or using vascular catheters often pre fer the larger, white-faced breeds because of their correspon dingly more prominent peripheral blood vessels. There is also considerable variation between breeds in their fecundity, wool length, hardiness to temperature extremes, and other param eters of potential interest (Briggs, 1969; Owen, 1976) .
Pregnant or possibly pregnant ewes are to be avoided unless specifically required. Q fever, a zoonotic disease, is dissemi nated via ovine milk and placental fluids (see Chapter 22 by Fox et al.) More commonly, ewes in late gestation are suscep tible to potentially fatal metabolic disorders such as hypocalcemia and pregnancy toxemia (Jensen and Swift, 1982) .
Many of the considerations given to sheep also apply to goats. Goats may be more vocal, gregarious, and more apt to escape from their enclosures. Goats are somewhat less season al than sheep in their reproductive activity, and management practices can be designed to extend the breeding season. Even so, kids are still difficult to find in the late summer and fall. Nonpregnant does are preferred whenever it is compatible with the experimental design. Intact adult bucks are to be avoided due to their offensive odor, which is most prominent during the breeding season. Wethers and intact males (either goats or sheep) are at risk in developing urethral calculi. Treatment usually involves extensive therapy or surgery and is laborious (Blood et al., 1979) .
Older animals are generally to be avoided because of the cumulative effects of parasites and likelihood of chronic dis eases. Very young goats are also to be avoided because they are more likely to develop infectious respiratory and gastroin testinal problems and may require more care and attention than more mature animals.
Calves may be purchased directly from a local dairy or through a sale yard. The latter source often provides animals that are of poorer quality due to colostrum deprivation or ill ness. It is an absolute necessity that a research project requir ing calves contract with a local dairy to supply calves that are known to have had adequate colostrum intake and are in a good nutritional state before they are acquired for research. Even better is the acquisition of weaned calves or calves that have at least started to consume solids. Calf husbandry and related health considerations are discussed elsewhere (Appleman and Owen, 1974; Blackmer, 1981) .
Adult cattle are seldom encountered in animal facilities un less used in agricultural research. Feeder cattle are commonly available at sale yards just after weaning in autumn. Older cat tle from sales yards are often culls and were eliminated from herds because of chronic illness. Often an animal that would not be satisfactory in a production situation might be an accept able blood donor, for example, but any potential research ani mal should be scrutinized for defects that may limit its useful ness. One should be cognizant of breed differences in size, temperament, production, etc. (Briggs, 1969) .
Disease prevention, through a well-managed immunization and parasite control program at the location where the animals are bred and reared, is the best means to provide investigators with good quality subjects. Animals from livestock dealers and feed lots often have no known history. Depending on the sea son, the region, and age of the animals, incoming animals may arrive with internal and external parasites, other infectious dis eases, or injuries acquired in transit. Even animals that were previously in good health prior to sale may have been substan tially stressed (e.g., by transportation, food or water depriva-tion, cold or heat exposure) and exposed to infectious agents in the process of marketing. The additional stresses of manipula tion, weighing, identification, and changes in husbandry im posed by the research facility may further compromise the ani mal's immune system. Therefore, it is necessary to establish an effective health screening protocol for an animal when it arrives and peri odically thereafter. The exact nature of the screening program will vary with the species, geographic area and associated en demic diseases, the needs of the particular research project, and economic considerations. Therefore, incoming animals should be given a thorough physical examination by a clinical veterinarian who is familiar with the particular species and as sociated diseases. In addition, samples of blood, feces, and other pertinent biological materials should be obtained for lab oratory evaluation. General guidelines are given below. More detailed discussion of this important phase of animal manage ment is presented by Blood et al. (1979) .
Animals should be examined visually for signs of disease or abnormalities immediately upon arrival. Healthy animals are alert, active, and inquisitive. The skin should be clean and free from scurf, and the haircoat should have a healthy appearance. Pruritus, alopecia, and lichenification may be evident. These conditions can be associated with ectoparasites, dermatophytes, or poor nutrition. The animal's conformation should be bilaterally symmetrical, and there should be good muscle mass and adequate subcutaneous fat. The animal should move about easily, stand squarely on all four feet, and show no signs of lameness. The animal should not show respiratory distress after moderate exercise in the pen and should not cough. The eyes should be clear and bright. Any animal showing obvious abnormalities of conformation or signs of illness such as la bored breathing, extension of the neck and panting after mini mal exertion, abnormal nasal or ocular discharges, dermal problems, lameness, diarrhea, or emaciation should be re jected immediately. Other, more specific procedures are also indicated for each species and discussed below.
Animals should be permanently identified at the time of the initial physical examination, using ear tags, ear notches, tat toos, freeze brands, or neck chains with identification tags as appropriate for the species (Pond and Maner, 1974; Owen, 1976) . It is recommended that a dual identification system be adopted to allow for occasional identification failures. Nonpharmacological methods of restraint may be necessary; these are presented by Conner (1978) .
The animal's body weight should be obtained upon arrival. Recording the animal's body weight for several days or weeks after arrival provides an excellent indication of the animal's health status and how well it is adapting to husbandry and sur roundings in the facility.
Animals that have been accepted after the initial screening procedures should be housed in isolation for 2 to 4 weeks.
During this conditioning period, animals can become accli mated to their new environment and learn to use the feeding and watering devices, as well as adjust to the husbandry rou tines. Each animal should be handled daily where appropriate and allowed to adapt to the conditions of the laboratory prior to incorporation in the research project.
Newly arrived ruminants should be provided with good qual ity hay ad libitum. If pelleted feed or concentrates are to be the bulk of their diet, the change from a roughage diet should be made gradually; no concentrates should be offered during the first 48 hr after arrival.
Nasal exudates in sheep are often caused by Oestrus ovis larval infestation of the nasal cavity and sinuses. Such infesta tion is very common in most parts of the United States during the summer and fall, and is of little significance to the animal. It is often impractical to reject sheep on the basis of a nasal discharge if the animals appear to be in good health otherwise. Sheep with acute pneumonia are usually coughing, febrile, and depressed. Sheep with chronic, low-grade pneumonia are often clinically normal but may produce problems later. Such ani mals are likely to develop clinical pneumonia after stress (e.g., anesthesia or surgery) and, in any case, have abnormal lungs. Detecting subclinical pneumonia via radiography is usually impractical; accurate diagnosis of pneumonia by auscultation is difficult. Animals with chronic pneumonia may sometimes be identified by exercise intolerance after running the flock around the pen; other signs, such as coughing or labored breathing, may also be evident.
A variety of vaccines are available for sheep. Standard biologics include those for tetanus and enterotoxemia. Considera tion should be given to vaccinating incoming animals for con tagious ecthyma (orf, soremouth), since the disease is zoonotic, and investigators are likely to handle the sheep's mouth for endotracheal intubation or oral medication.
Sheep should be palpated carefully for superficial abscesses caused by Corynebacterium psuedotuberculosis, and affected animals should be rejected. Incoming sheep should also be ex amined for ectoparasites such as sheep keds and lice, and dip ped with an appropriate insecticide/miticide. Products de signed for agricultural use (e.g., toxaphene) are often more residual than is necessary or desirable in a vivarium. Less re sidual insecticides designed for use on dogs and cats (e.g., carbaryl and pyrethrins) are equally effective and preferred for a research facility.
The hooves of incoming sheep should be examined and trimmed if necessary. If foot rot (caused by Fusobacterium nodosum) is present, the affected tissue should be trimmed and appropriate topical and parenteral therapy instituted (Jensen and Swift, 1982) . If copper sulfate solutions are used, sheep must be closely monitored due to the toxicity of ingested cop per compounds for sheep. If damage to the hoof is so extensive that the affected tissue cannot easily be removed or such that the animal will be left with a permanent lameness, the animal should be rejected. Introduction of foot rot organisms via a new sheep may also cause considerable problems for other sheep in the facility, given the durability of the causative bacterium.
Many of the comments made for sheep are also applicable to goats. In general, goats are less likely to harbor chronic pneu monias, are somewhat more hardy, and much cleaner than sheep. Goats are less susceptible to nasal bots and less likely to develop contagious ecthyma. Parasitism and anemia are as great if not more of a problem in goats versus sheep. Foot rot as a specific bacterial infection is less of a problem in goats, although their hooves can become overgrown and require the same care as for sheep. Tetanus and enterotoxemia vaccines should be considered for all goats.
Goats and sheep are easily aged by examining their incisor teeth (see Appendix, Table A .IV) (Habel, 1978) . This should be done on all incoming animals and noted on their records. Animals who have lost any incisor teeth are usually too old to provide a good research subject, especially for long-term stud ies, and should be avoided.
Mandibular, prescapular, prefemoral, and supramammary lymph nodes should be palpated for Corynebacterium ab scesses, and affected animals rejected. Chronic arthritis in goats can be caused by mycoplasmal or viral infections, and is undesirable in research animals. Animals exhibiting lameness or swollen, painful joints should not be accepted.
As with other species, the most important aspect of a screen ing program is the health status of the source herd. A thorough physical examination is conducted at the time of arrival. The amount of subcutaneous fat should be appropriate to the age and type of the animal. Common abnormal findings include diarrhea, respiratory infections, and dermatologie disease. Lichenification of the skin is often seen and is indicative of either dietary zinc deficiency or ectoparasites. Pediculosis and mange are particularly common in swine.
Respiratory infections are common; nasal discharge or devia-tion of the snout (due to atrophie rhinitis) is grounds for rejec tion. Because a great variety of infectious agents can cause enteric infections in swine, it is highly advisable to separate lots of animals by time of arrival, and animals from different sources. Any pig with diarrhea should be removed from the premise altogether or placed in quarantine as soon as possible.
For these reasons alone, procurement of specific pathogen-free (SPF) pigs is recommended, especially if large numbers of swine are used. Young pigs may be anemic due to dietary iron deficiency, and it is prudent to routinely administer iron dextran intra muscularly to newly arrived young swine. Vaccination reg imens should be appropriate for the herd history and geograph ic locale (Pond and Houpt, 1978; Baker, 1975) .
Young calves should be observed to make certain they can obtain feed from the feeders in the facility. If there is any doubt, the calf should also be fed a milk replacer until it is capable of eating conventional feeds (Appleman and Owen, 1974; Schugel, 1981) . Pneumonia and diarrhea are the most common disease entities in young calves. The most important health management factor for a young calf is making certain the animal obtained an adequate supply of colostrum. Co lostrum should be force-fed at 50-80 ml/kg within the first 2 hr after birth, and at a total dose of 8-10% of body weight daily for at least the first 48 hr (Blackmer, 1981; Radostits, 1981) . In addition, the navel should be disinfected with iodine immediately after birth to avoid other common neonatal condi tions, such as navel ill and joint ill. Calves that are febrile or hypothermie, depressed, cough frequently, exhibit severe diar rhea, or are anorectic are poor candidates for research.
Mature cattle should be observed carefully for 10-12 days after arrival for signs of shipping fever complex. Animals that cough or are febrile should be treated immediately with intra venous, broad-spectrum antibiotics (e.g., tetracyclines at 10 mg/kg intravenous). Fecal flotation should be performed for incoming lots of animals. If substantial levels of parasite ova are found (see below), appropriate anthelmintics should be ad ministered. It may be desirable to obtain blood samples for brucellosis testing and to test for tuberculosis via intradermal tuberculin testing, depending on the background of the animal and the prevalence of disease in the region. Brucellosis vac cination of heifer calves may also be necessary, depending on state regulations. Infectious keratoconjunctivitis is common in the summer and fall in animals housed outdoors, and infected animals should be isolated and treated immediately (Blood et al, 1979) .
Quarterly health maintenance should include recording each animal's condition and body weight, fecal floatation assay and worming, and appropriate vaccinations if needed. Shearing of most sheep breeds and some goat breeds is required at least every spring. Crutching of sheep (shearing the escutcheon and udder) may be indicated even more frequently for optimal cleanliness and health.
Daily monitoring of feed intake is one of the easiest and most cost-effective methods of detecting disease. Anorexia or poor appetite for longer than 1 day, or any weight change greater than 10% from the previous weight (other than weight change due to maturation, pregnancy, or parturition) is sufficient grounds for a physical examination.
Parasite control is particularly important where animals are housed in groups or on pasture. It is seldom possible to main tain ruminants as parasite-free. Ungulates on overcrowded, moist pastures without a grazing rotation scheme are more likely to need frequent worming to maintain parasite loads at subclinical levels. Actual tgg counts are more useful in deter mining levels of parasite load than merely reporting the pres ence of a particular parasite. Any results greater than the fol lowing values are indications for anthelmintic therapy: cattle, 75-150 ova/gm feces (fresh weight); sheep and goats, 300-400 ova/gm feces; swine, 50-100 ascarid ova/gm feces (R. B. Wescott, personal communication). Dosages for anthelmintics and other parasiticides are presented in the Appendix, Table A .XVI.
Good husbandry practices include examination of hoove, and feet at least quarterly. Confined animals or those running on soft surfaces will have insufficient hoof wear and will re quire trimming. Good sanitation, pasture rotation, and main taining dry surfaces will greatly reduce or eliminate the inci dence of hoof problems.
Nutritional diseases can be avoided by providing a balanced diet of good quality feed. Guidelines for nutritional require ments have been established for each species and are updated every several years (National Research Council, 1975 , 1976 , 1978b . Daily nutrient requirements are presented in the Appendix, Table A .III. One problem to recognize is copper accumulation and toxicosis in sheep housed indoors or in me tabolism cages for long periods (Blood et al., 1979) .
Infectious disease is generally not a major problem in a closed system unless the animal turnover rate is high. In de signing a vaccine protocol, factors such as the age, phys iological and immunological state of the animal, cleanliness of the environment, exposure to recent arrivals of the same or different species, and those diseases endemic to the region where the animals originated as well as where they are housed should all be considered (Todd, 1981) . However, vaccines may not provide adequate protection, especially if they are used in response to a disease outbreak as opposed to use in a pre ventati ve medicine program. Furthermore, all persons in volved in the implementation of a particular preventive medi cine program must understand the program's design, purpose, and how to execute it properly. This is accomplished by educa tion, assistance, and monitoring of personnel in a constant effort to maintain the health of the research animal population.
The purpose of synchronizing ovulation is to provide for more efficient use of artificial insemination or timed pregnan cies, as well as preparing animals for embryo transfer. Con ventional protocols utilize hormones or hormone analogs that may override endogenous endocrinological patterns (Jochle and Lamond, 1980) . Prior to attempting ovulation synchro nization, breeding evaluations both for male and female com ponents are necessary in order to maximize success. In addi tion, the females to be used must be cycling normally.
Two strategies can be employed. One is to suppress ovarian activity with progestins, which will sustain corpora lutea and arrest follicle maturation. After the inhibitory agent is with drawn at the prescribed time, this allows internally coordinated follicular development and ovulation to occur. This approach is best applied for sheep (Quinlivan, 1980) . The second strat egy is induction of premature regression of the corpus luteum, using either exogenous or endogenous prostaglandin F 2tt . This promotes the ovary to the proestrous state, with ovulation fol lowing at a known interval. This strategy is useful for cattle (Kaltenbach, 1980) .
Gonadotropins have been used for estrus induction in swine (Leman and Dzuik, 1975) . Progestin regimens can also be ap plied to swine, but nonpharmacological methods are often just as successful. For immature females (gilts) that are at least 6 months old, estrous ovulation occurs several days after ex posure to a boar or its scent or a stressful episode, such as transport. For lactating sows, weaning the litter usually results in estrus several days later.
Livestock facilities must be designed with the following pa rameters in mind: ease of containment, handling, and transport of animals; minimization of routes of escape of animals and injury to animals and personnel; ease of maintenance and re-pairs; allowance for efficient ventilation and avoidance of tem perature extremes; and allowance for effective sanitation and waste removal. Several publications are available that address livestock facilities (Jennings, 1974; Sainsbury and Sainsbury, 1979; National Research Council, 1971 , 1974b . Recom mended minimum space allowances are presented in the Ap pendix, Table A .VI.
If space is available and the climate is not too severe, most ungulates are more efficiently housed in well-drained outdoor pens, pastures, and barns. Outdoor livestock facilities reduce labor expenses and provide an open fresh air environment where there is space for ample exercise and allowance for indi vidual territorial needs. Animals housed outdoors require the same careful observation and management provided for ani mals housed indoors. Pastures can be effective means of hous ing animals that are to be held for long periods of time without significant handling. Pastures require careful management to prevent overgrazing; rotation is necessary to allow the flora to recover (Ensminger and Olentine, 1978; Owen, 1976) . De pending on the circumstances, pastures for livestock may not be cost effective when expenses for seeding, fertilizer, weed control, irrigation, fencing, and gastrointestinal parasite con trol are considered.
High density stocking of either an indoor or outdoor facility leads to more excreta per surface area, as well as competition between animals for space, feed, and water. These results lead to increased incidence of injuries, stress, and disease. In win ter, outdoor facilities must provide a dry, draft-free area where animals can keep warm. In hot, arid climates, protection from direct sunlight is very important for confined animals. Ample fresh water and mineral salts must always be available. Since labor is often at least 50% of animal per diem costs, efficiency is a primary consideration for fence placement, building de sign, equipment utilization, and labor management.
Selection of building materials for fences and buildings will vary with budgets and climates. Although the initial invest ment may be higher, concrete floors and walls plus metal fences and gates minimize injury to the animals and reduce maintenance costs. Concrete-surfaced pens and corrals facili tate sanitation and, if sloped properly, provide adequate drain age for dry footing for the animals. The slope of flooring sur faces for drainage should be 0.25-0.5 in./foot. Manure in dry lots may be scraped into holding areas or piles or removed. The manure pile is a cost-effective method of cleaning, and the high temperatures generating by the resultant composting ac tivity effectively destroys most potential pathogens. Smaller pens or those with high stocking densities can be cleaned by hosing with water or steam.
Concrete flooring can be finished in a variety of surfaces. The rougher the surface, the more difficult it will be to clean but it also offers more secure footing. Animals are therefore less likely to slip and injure themselves, e.g., fractured femurs DALE L. BROOKS, PHILIP C. TILLMAN, AND STEVEN M. NIEMI and tuber coxae occur occasionally in excited cattle. The rougher surface may also cause initial, minor lameness prob lems due to abrasion, especially for animals previously main tained on irrigated pasture.
High-pressure water hoses greatly facilitate cleaning con crete flooring. Sanitation can be enhanced by use of in-line disinfectant and detergent proportionators with the water sys tem. A minimum 6-in diameter sewage drain with trap-type basket is necessary to avoid blockage of the sewage system by hay and bedding materials.
A dry, clean resting area provides comfort for large animals. The area can be made of rubber matting (4 ft x 8 ft x 1 in.), a space with thick straw or wood shavings, or a concrete curbed area containing dirt or sand bedding that the animals may enter or leave easily. The added bedding materials provide extra comfort. Divider panels will provide for individual space, thus minimizing fighting and injuries. An outside lounging area should be shelterd by a 10-ft or higher roof.
Fences constructed of tubular or U-shaped angle iron type metal for pens and corrals are the safest types, and have low maintenance costs. High wooden fences (5 to 6 ft tall) or fences made with galvanized metal or preserved wood posts are less costly to install but are more likely to cause injuries. However, they are satisfactory on pastures where animals have more space and are less likely to challenge the fences. Alterna tives include electric fencing and wire mesh fencing. The latter type is commonly used to protect livestock from predators, especially small ruminants from feral dogs.
Wooden rail fences should be avoided. Penned animals that are bored may become avid wood chewers. Most wood preser vatives and anti-chewing wood coatings contain pentachlorophenol or creosote compounds that may be toxic if licked or chewed. Fences that are high enough to prevent animals from hanging their heads over them will greatly reduce repairs and injuries, prolonging the lifespan of the fence. Electrically charged wire along the top of the fence will also keep animals off.
Feed bunkers should be made of galvanized metal and should be adjustable so they can be set at the animal's chest to eye level height. The contamination of feed by feces and urine can be greatly reduced if adjustable feeders are hung as high as possible, yet still allowing the animal to eat. For small ungu lates, commercial hog self-feeders attached to the fence panels are safe and readily available. These J-type feeders have a flip top cover over the animals feeding trough and another cover over the feed supply keeping the feed dry and clean. Goats and pigs quickly learn how to flip up the lower lid for access to feed. Some animals, especially sheep, may require these lids to be propped open at first. Some animals never learn how to open this lid or how to drink from automatic waterers. Animal caretakers should be aware of such cases so that these animals can be fed and watered by other means.
Free access to clean, fresh, cool water is a necessity at all times. Most domestic animals can survive when inadvertently not fed for a few meals, but lack of water can be fatal after 24-48 hr or less in some climates. "Salt poisoning" is a par ticularly rapid and fatal syndrome that is seen in newly arrived swine that are not able to gain access to water quickly enough (Smith, 1975) .
Some facilities use automatic watering devices of the bowl type with a metal float that must be depressed by the animal's chin and muzzle as it drinks, activating the valve to provide additional water to the bowl. A better device is a small trough with a free open area large enough for the animals to drink and an adjacent, protectively covered area containing a small, toi let bowl-type float that governs the water level. This watering mechanism is easier for animals to use, but unless properly constructed, it is easily broken. Leaking waterers may provide excessive ground moisture around the trough, increasing the incidence of foot rot and providing a breeding place for flies. Drylots and pastures should have concrete pads under and around waterers and feeders to reduce muddy conditions.
Water quality is an important aspect of husbandry that is often overlooked. Groundwater can be a source of essential nutrients, sometimes in inappropriate or harmful concentra tions. In addition, there are other substances (e.g., toxic com pounds, carcinogens) found in drinking water that may have a substantial impact on physiology and production (National Re search Council, 1974a).
Low-roofed animal shelters, especially corrugated metal ones with an interior ceiling height of less than 10 ft, can act as ovens in hot weather. In cold weather, condensation of evapo rated water may occur on metal ceilings and thus dampen the animals. Ventilation must be provided by higher roof peaks, roof ridge vents, exhaust fans, eaves vents, or sliding barn doors along the sides of the shelter. Roof insulation helps pre vent both overheating in the summer and condensation in the winter. Other publications discuss ventilation and building de sign in detail (Sainsbury and Sainsbury, 1979; Bates and An derson, 1979; Anderson and Bates, 1979) .
Corrals, pens, shelter, weighing scales, restraint chutes, and stocks should be located on ground higher than the intercon necting paved service and livestock driving lanes to provide adequate drainage. These lanes should, in turn, drain to a col lecting dump or ditch or into an ample sewage drain. Local public utilities districts may have regulations restricting the type and quantity of organic materials entering public waste disposal and drainage systems.
Livestock truck and trailer loading chutes and a system of connecting lanes are essential to move livestock, feed, manure trucks, and vehicles between holding areas and the pastures, barns, and dry lots in the facility. Walk-on scales, chutes, and stocks provide safety to livestock and personnel, and are all prime components of a large animal facility.
Feed preparation and storage areas are often needed for un gulate diets that contain a high percentage of hay and bulk feeds. The quantities of foodstuffs may require large hay barns, bulk storage tanks, and special feed choppers and mix ers, i.e., much more space than required for the customary feeds used for other laboratory animal species. The summer temperature in improperly dried hay stacks and bulk storage tanks is often very high, so feeds not used quickly may become deficient for heat-labile nutrients. Hay and bulk feeds should be stored where there is adequate ventilation and protection from heat, moisture, and direct sunlight (Ensminger and Olentine, 1978) .
In some facilities, especially those in urban areas and for research involving infectious or biohazardous materials, spe cialized containment rooms are needed to control the environ ment and to prevent the spread of contamination. The large volumes of feed, bedding, and waste present problems of space, labor, and traffic flow.
Indoor housing must provide safety to animals and person nel, be dry, draft-free but adequately ventilated, easily cleaned, and have low maintenance costs. Slatted floors are recommended for swine and sheep. Alternatively, good ab sorptive bedding helps control ammonia levels from the large volume of urine and feces. In some environments and for some protocols, hosing cannot be used in cleaning because it raises relative humidity to 70-95% for 1-2 hr afterward. This sud den fluctuation in the room's environment predisposes animals to respiratory diseases. Effective air vents and mechanical hu midity controls are thus often necessary to maintain low moisture levels, in order to avoid increased incidence of pneu monia and diarrhea. This is especially true for young, co lostrum-deprived animals and animals harboring subclinical infections or chronic conditions. Furthermore, ruminants are much more tolerant of cold temperatures due to the amount of heat released by ruminai activity, and thrive at temperatures that are deleterious for other mammals.
Some ungulate diseases are easily transmitted via aerosol to other animals and personnel. Thus, many of the concepts of a controlled rodent room must also be established for the indoor housing of livestock. For example, exposure of personnel via direct or indirect contact in common traffic flow patterns and recirculated air ventilation systems caused Q fever zoonotics in vivaria where pregnant sheep were housed (see Chapter 22 by Fox et al.) .
Footbaths are often used in livestock facilities as a means of disinfecting the boots of personnel. Although they can be useful if used properly, footbaths should not be relied upon alone to prevent foot traffic contamination. More often than not, these disinfectant foot tubs become contaminated with bedding, manure, and other organic material that can quickly inactivate the disinfectant. If footbaths are to be useful, their contamination with excess organic material must be minimized by having workers wash debris from boots before leaving the animal room. The disinfectant must be monitored and changed once or twice daily in order to maintain its effectiveness.
A better system for sanitation is the use of a separate pair of rubber boots or disposable plastic foot covers for each room. Many experiments are most effectively confined by the use of reusable clothing or disposable clothing only used in the spe cific animal room. In addition to overalls, other equipment, such as foot covers, head covers, gloves, face masks, and well-fitted respirators may also be required.
Whenever a maximum security (P4) containment area is re quired for ungulate studies, the usual requirements of smaller animals (e.g., rodents) are further compounded by the in creased body size and greater quantities of feed, water, urine, and feces involved. This increased bulk requires larger sewage drains and larger rooms with built-in or portable restraint pan els. Sewage systems may require larger waste-liquid holding tanks that can be decontaminated and held for a period of time as needed, prior to pumping or release into the standard sewage system. Solid wastes are usually put into garbage cans with sealable lids that can have a liquid decontaminator added or have the outside sprayed with a disinfectant or covered with two autoclavable bags prior to moving into the dirty side exit room for holding or autoclaving. The use of double bagging protocol helps reduce accidental contamination. Autoclaves must be able to draw a complete vacuum to provide the deep steam penetration necessary for baled hay, straw wood shav ings, garbage cans, bagged whole or quartered animals. In some facilities, depending on the type of contaminants, these bagged materials or animals are incinerated instead of autoclaved. Publications are available for further information on biocontainment procedures and facilities (Subcommittee on Arbovirus Laboratory Safety, 1980; U.S. Public Health Ser vice, 1983) .
The parameters in Tables A.I-A.V are expressed as a range of normal values. The values were obtained from data col lected by the University of California, Davis, Veterinary Med ical, Teaching Hospital, and other sources (Benjamin, 1978; Pond and Houpt, 1978; Blood et al., 1979) . B, whole blood; S, serum; P, plasma; HP, heparinized plasma; R, erythrocytes.
The exact nutrient requirements of any animal are a function of the animal's age, sex, growth rate, and status of pregnancy or lactation. The information in this table provides requirements for the size and type of each species most often found in research facilities. The values presented for ruminants are calculated on a 100% dry matter basis; for swine, a 90% dry matter basis is used. Investigators formulating rations should consult the official nutrition guidelines established by the National Research Council (1975 Council ( , 1976 Council ( , 1978b Council ( , 1979 .
^Elemental sulfur is not required by swine since they utilize sulfur-containing amino acids. ( Deficiency rare or absent in natural diets. J N/K, nutrient is required, but exact amount is not known. ''Vitamin E may be required for nursing animals, but not for adults in geographic regions where selenium levels are adequate. ■' S, synthesized by rumen microflora; not required in feed.
Data in Tables A.VII-A.XV are from Doig et al. (1981) ; Gillespie and Timoney (1981) ; Jasper (1982) ; Jensen and Swift (1982) ; Kahrs (1981) ; Livingston and Gauer (1982) ; Mohanty and Dutta (1981) ; Stalheim (1983) ; U.S. Department of Agri culture (1978) ; and pertinent chapters in Dunne and Leman (1975) . Asterisked entries indicate diseases that are not encountered in the United States or Canada, but may be found in other developed countries. C, cardiovascular; D, digestive; H, hemolymphatic; I, intergument; M, musculoskeletal; Ma, mammary; N, nervous; R, respiratory; U, urogenital.
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