HUSBANDRY

Guidelines for housing laboratory swine have been published in the Guide for the Care and Use of Laboratory Animals (Guide) (NRC, 1985) and in the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching (Ag Guide) (Consortium for Developing a Guide, 1988), which require that swine be housed in facilities comparable to a well-managed farm. Also, the proceedings of a Scientists Center for Animal Welfare conference provide recommendations for husbandry and handling of swine (Mench et al., 1992). Although agricultural animals, including swine, are now covered by the Animal Welfare Act and consequently are regulated by the U.S. Department of Agriculture, no written standards are available to date. While the guidelines listed above do not take miniature pigs into consideration, a comparison of husbandry practices for miniature pigs with those of domestic farm breeds has recently been published (Fisher, 1993).



The recommendations in both the Guide and the Ag Guide for housing and grouping swine are confusing and contradictory and neither takes miniature pigs into consideration. The Guide has more stringent requirements for floor space than the Ag Guide and should be used as the standard for biomedical institutions. The Guide requires 6 to 60 square feet per pig (0.56-5.57 sq m/pig) depending upon the body weight and the number of animals housed within the same enclosure. It does not distinguish between a sow with a litter and groupings of more mature animals. The Ag Guide recommends 35 sq ft (3.15 sq m) for a sow with a litter. In our experience, miniature pigs with litters actually require less space than could be calculated from the standards in either document. A variance of this type should be reviewed by the institution's IACUC.



Ambient temperature requirements for swine are not listed in the Guide, but the Ag Guide recommends a temperature range of 50�-77�F (10�-25�C) for adult animals and temperature ranges of 590-90� (15�-32�C) for less mature animals with the higher values being required for neonates. Based on our experience with miniature swine, temperatures should be between 75�-80�F (24�-26�C). Heat lamps or other heat sources should be placed in the comer of the cage to provide extra warmth for neonates, which typically require temperatures of 85�-90�F (30�-32�C). Care must be taken to ensure that temperature measurements are made at the level of the animals because of the differential between the floor and wall thermostats (Fisher, 1993). Care should also be taken to ensure that animals are kept dry while the pens are being cleaned, as wet animals frequently become chilled. Animals housed in agricultural situations can withstand a wide range of temperatures if shelter is available.



Humidity and air changes are not detailed by existing guidelines. We use rooms with 10-15 air changes per hour with 100 percent fresh outside air and a relative humidity of 40-70 percent, which is consistent with general American Association for Accreditation of Laboratory Animal Care (AAALAC) facility standards. If lighting is provided by artificial means with light timers, the lighted cycle should be 12-16 hours especially if breeding is performed (Consortium for Developing a Guide, 1988; Fisher, 1993).



Swine are best housed in pens made of chain link or panels with vertical slats or bars. If solid floors are used, they should be deeply bedded with wood shavings to prevent the animals from slipping. The wood shavings also provide environmental enrichment as they are a substance in which the pigs can root. Extra care must be taken when using wood shavings with animals that are being fasted before surgery, as they will eat the bedding. Raised slotted flooring or slatted floors are also acceptable as long as a type with small openings is used to prevent hoof injury (Figure 1). If animals are housed on raised floors, a regular program of hoof trimming will have to be provided for long-term animals (those held for more than 3 months). Dog cages provide good short-term housing for special purposes such as post-operative care, however, either raised floors or non-skid pads need to be placed in the cages.



Facilities that maintain breeding swine need to provide for farrowing and weaning. Domestic farm breeds, but not miniature breeds, require a farrowing crate or pen to prevent them from crushing the piglets. If the piglets are allowed access to heat lamps and bedding for warmth, it is our experience that farrowing crams or even separation panels are unnecessary. Piglets will start to consume feed at approximately 3 weeks, and the starter ration should be provided in an area of the pen not accessible by the sow. Domestic farm breeds have an average gestation period of 114 days, while some of the miniature breeds farrow at shorter times (for example, the Yucatan pig has a gestation period of 111 days). Weaning for both domestic and miniature breeds occurs at 3 to 6 weeks.



Swine are social animals and should be provided with the opportunity to interact with other members of their species and with humans. If housing by compatible groups is not possible because of protocol restrictions or cage size, then animals should be able to see each other and preferably touch noses through the walls of the pens. Incompatible animals will fight and dominant animals may severely injure others in the pen especially at feeding time. If animals are housed without bedding, then toys such as basketballs or large balls made of impervious materials can be provided to satisfy the rooting behavior. Swine can be trained and made docile by positive interactions with humans such as rubbing or scratching the head and back. Animals may also be trained with food rewards of vegetables or fruit. Stressful housing situations in combination with other factors, including diet and environmental fluctuations, may result in gastric ulceration (Panepinto, 1986; Swindle et al., 1988).



In biomedical research institutions, standard formulations of commercial agricultural feed should be avoided. Commercial farm rations are designed to provide rapid growth and contain antibiotics and other growth promoters unless special formulations are requested. Several commercial manufacturers now provide diets for miniature pigs which are higher in fiber and provide for less rapid growth without compromising nutritional requirements. Starter, maintenance, and lactation diets are available and a calculated amount may be fed either once or twice a day. Pigs will readily consume medications mixed in normal rations or camouflaged with either canned dog food or chocolate syrup. Pigs will form a dunging pattern and will usually defecate opposite from where their food is provided depending upon the cage configuration. More information on nutrient requirements for swine can be found in NRC (1988).



Water is best provided by an automated watering system as water deprivation can easily occur because pigs will refuse to drink from soiled water containers and quickly overturn floor pans and water bowls. Care must be taken not to deprive them of water for long periods of time, even preoperatively, because they are susceptible to "salt poisoning.'' This condition results in clinical neurologic deficits secondary to water deprivation or over-administration of sodium salts in as little as 12 hours (Fisher, 1993).