Mouse Husbandry Animal husbandry is the applied science of providing an optimal environment for a population of animals.

The practice of mouse husbandry encompasses all of the activities necessary to produce mice of high quality, including care and feeding, cleaning of the equipment and physical surroundings, and constant concern for the health of each animal. The implementation of good mouse husbandry begins with the design and construction of the physical facilities and continues through maintenance of an environment conducive to good health, growth, reproduction, and survival of the animals.

Room environment Rodents do not have sweat glands and are unable to pant.  This makes them prone to heat stress if the cage or room temperature is improperly regulated.    The acceptable temperature range mice is 64 - 79  F.  Humidity should be maintained between 30 - 70%.  12 to 14 hours light per day (use automatic timers) 14 hours light for breeding

Racks and shelving Racks for cages may be either mobile of fixed. Fixed racks can be attached to the floor, the walls, or the ceiling. The bottom shelf of a rack should be no less than 6 in. off the floor; the top shelf no higher than the reach of a person of average height. Shelves may be made of metal pipe or rods, or they may be solid sheet metal like book shelves

Cages Materials for construction of cages include galvanized and stainless steel, plastic, wood, glass, and paper. The most common type of mouse cage for a breeding pair is a plastic box approximately 12 x 6 x 6 in. deep. Cages are available commercially with many dimensional variations of this basic design.

Desirable features of cage design are the following The cages should be seamless and designed for easy cleaning They should confine the mice adequately without restricting movement; there should be about 8 sq in. of floor space per adult mouse They should be stackable without binding They should be light in weight, yet sufficiently sturdy to withstand repeated washing and rough handling They should be resistant to the corrosive effects of mouse urine

Covers Covers for mouse cages are usually made of metal, either of punched sheets, hardware cloth, rods, or expanding metal. The material can be stainless steel, aluminum, or metal.

Water Water may best be supplied from bottles resting on top of the cages. Each bottle is fitted with a rubber stopper and a tube of stainless steel. The tube must be constricted at the end so that the water does not flow out unless the mouse licks the end of the spout. The diameter of the tube should be ¼ to 3/8 in. If the water bottle rests on top of the cover, the tube must be bent at an angle of about 105° The tip of the tube should reach a point about 2 in. above the floor of the cage

Bedding and nesting material Bedding material serves three purposes: to provide material from which the mice can make nests, to absorb the fecal and urine wastes, and to provide insulation. Among the materials in common use wood shavings, ground-up corn cobs, chopped straw, hay, shredded paper, paper strands.

Bedding The bedding should be about ¾ in. deep in the case of shavings and other fluffy material. In any case, it should be sufficient to absorb all of the urine, wet fecal matter, and water which may drip from the water bottle . The frequency of cage changing depends on several factors. If wood shavings or similar material is used as bedding, the cages should be changed at least once a week and in some cases twice a week.

Feed and feeding Mouse food is commercially available in the form of pellets. Some manufacturers can supply several varieties for specific purposes, e.g., a special formulation for breeding mice, pasteurized feed for mice maintained under pathogen-free conditions, sterilized diets for germ-free mice, diets fortified with extra amounts of heat-labile vitamins (for installations where the feed is autoclaved before it is brought into a mouse room), and diets with specified levels of fat or protein

Breeding colony

Overview Factors affecting breeding performance Data collection and good colony management Breeding schemes Cryopreservation

Mouse Reproductive Milestones Litter size: 1 to 20 pups/liter (6-12 av.) Weaning age: 21-28 days Sexual maturity: 6 to 8 weeks Productive breeding life: 7-9 months Gestation: 19 to 21 days

Influence of Genetic Background on Breeding Performance Behavior Hybrid vigor Birth defects

Mutation/transgenic-associated breeding problems Infertility (either gender) Mammary function Embryonic lethality Abnormal behavior poor mothering instinct aggression Shortened breeding life span tumor development neurodegeneration Severity may be affected by genetic background

Non-genetic Factors that Influence Breeding Performance Environment Temperature Light intensity and light cycle Noise and vibrations (construction, equipment) Air pressure Odors (toxic fumes, perfumes) Handling consistency Over handling-leave pregnant mothers alone Caretaker changes Nutrition Health status

Data Collection and Record Keeping Critical for successful colony management

Data Collection and Record Keeping Collect breeding statistics -birth dates for every liter -interval between litters -litter size -number of mice that wean (wean:born ratio) Monitor genotype and gender frequencies for each breeding unit Pedigree records

Non-productive Breeder Criteria No litter produced - 40 days from date of first mating No new liters - 40 days from last born date No weaned pups - 2-3 litters with no wean

Tips for colony management Mate mice early, between 7-12 weeks of age Establish/collect breeding statistics Replace breeders on a rotation (weekly, monthly) - breeding life span typically 7-8 months - have young breeders available Keep good records, evaluate data regularly Remove non-productive breeders ASAP

Setting up a breeding cage The ideal way is to put 1 male and 2-6 females together. Once females get pregnant, move one pregnant female with a male to a new cage. Move two pregnant females to one cage. Separate the pups from the mother when they are one month old.

Setting up cages Tail clipping can be done after 18 days of age. When separating the pups from the mother, isolate males and females in different cages When the mice are 7 weeks of age, put them together for breeding.

Labeling the cage P.I.: Dr. Ira Tabas Investigator: Protocol No.: Account No.: Lab: PH9-405/406 Tel.: (713) 305-5669/3133                                                 

Cage cards

Cage cards

Mouse numbering system