22: Rabbits and Rodents

Question 1

Importance of understanding nutrition in these species?

Answer 1

• niche market for pet food
• lab animal nutrition
• food animals in some countries

Question 2

Orders, families of rabbits and mouse, rat, hamster

Answer 2

Rabbit = lagomorpha, leporidae

Mouse/rat = rodentia, muridae

Hamster = rodentia, cricetidae

Question 3

Main difference between lagomorpha and rodentia orders?

Answer 3

Digestive tract and teeth

Question 4

How are lagomorph teeth different?

Answer 4

Have 4 (2 pairs) incisors in upper jaw (not 2 like rodentia)

Lago are wholly herbivorous, while many rodents can eat meat and vegetation

Question 5

What type of digestive physiology do lagomorphs have? Diet?

Answer 5

Nonruminant herbivores

Monogastric species but still primarily a forage diet (high fiber) = causes a problem (how to get essential aa) w a unique solution

Question 6

What organ is unique in lagomorphs? How?

Answer 6

Cecum

Circular-structure
Specialized nervous physiology (tied to circadian rhythm)

Cellulytic bacteria

Question 7

How is the cecum tied to circadian rhythm?

Answer 7

Cecum can operate at two different speeds

At night, flow of digesta slows down = microbes have more time to work on undigested forage = more microbial protein

Produces diff feces (cecotropes) that are high in microbial protein which rabbits consume

Question 8

Circadian rhythm in lagomorphs during day vs night

Answer 8

Day = regular activity of GI tract, normal small fecal pellets

During night = tract motility reduced, bacteria in cecum and colon produce cecotropes (high in N/protein, low in fiber) which are consumed so rabbits can capture more N

Question 9

What are cecotropes high in? How do they allow rabbits to live on low protein food?

Answer 9

Protein, minerals and vitamins
Slide 12

They are high in microbial protein and rabbits have access to recycled N through coprophagy

Question 10

Consequences if coprophagy is prevented?

Answer 10

Reduced growth rate, lean body mass

Deficiency of amino acids

Question 11

Suckling and growth in rabbits

Answer 11

Suckle few times a day. At weaning, provide small amount of high Q forage

During growth, forage (fiber) is primary source of nutrients

Question 12

Diet of an adult rabbit

Answer 12

High fiber, low enegry

Question 13

Nutrition of rabbits in old age? What is a common issue in old age and why?

Answer 13

High fiber, low E diet cannot be supplied bc changes in teeth and reduced saliva flow
Digesta passage is slower

Gastric stasis (hair balls) are common
Reduced fiber intake/saliva production slows movement and hair balls will form

Question 14

Slide 16, 17

Answer 14

Life cycle nutrition in rabbits
Optimum fiber intake

Question 15

What should be added to a rabbits ration during lactation?

Answer 15

Higher crude protein in the form of soybean meal
Molasses (sugar)
Fat (provides more energy)

Slide 18

Question 16

Origin of the term rodent? Are they coprophagic?

Answer 16

To gnaw

Yes, feces rich in protein and B vitamins (only some produce cecotropes tho)

Question 17

Slide 20

Answer 17

GI physiology

Question 18

What are rodents named after?

Answer 18

Specific eating behaviour: hold food w forepaws, lower incisor teeth move back and forth against immobile upper incisors

Question 19

What are rats and mice typically fed?

Answer 19

‘Rat chow’ and ‘mouse chow’

Occasional special treat (vegetable or cooked meat)

Question 20

Protein requirement of rats and mice

Answer 20

Low (4-6% for maintenance, 13% growth, 18% repro)

Question 21

Slide 23

Answer 21

AIN 93 diet

Question 22

Overfeeding protein in rats and mice. Feeding them during lactation? Problem with group housing?

Answer 22

Not a concern for kidney function

During lactation, increase feed intake dramatically (4 to 5x maintenance)

Occasional cannibalism

Question 23

Why might irradiation be better than autoclaving for processing?

Answer 23

Irradiation = no heat (little chance of protein damage)

Autoclaving = heating with steam (protein damage)

Question 24

Guinea pig order? What do they eat? GI physiology? Coprophagy? Protein?

Answer 24

Rodentia

Herbivores

Enlarged cecum (semicircular) and colon

Coprophagy more important in guinea pigs than general rodents (they produce cecotrophs) bc require 18% protein

Question 25

Natural diet of guinea pigs

Answer 25

Green vegetation and fruit

Old food contained too little fiber and too much E (poor cecotroph formation)

Multiple small meals a day>

Question 26

Unique metabolism in guinea pigs

Answer 26

Require vitamin C in diet (cannot make ascorbic acid)

Connective tissue synthesis

Question 27

GI tract of hamsters? Protein requirement?

Answer 27

Stomach separated into cardiac and caudal regions
- first region acts similar to rumen

Require 15% protein
- need some legumes or oilseeds

Question 28

What should be supplemented in a hamsters diet?

Answer 28

Dark green and yellow vegetables

Question 29

Nutritional peculiarities in hamsters

Answer 29

Do not require vitamin D w proper Ca:P ratio (make it from cholesterol and sunlight)

Cholesterol metabolism:
- develop atherosclerosis quite easily (used to study heart disease)
- sensitive to dietary cholesterol