Laboratory Animal Nutrition

1
Laboratory Animal Nutrition

• Timo Nevalainen

Universities of Kuopio and Helsinki
www.uku.fi/tnevalai/Nutrition.ppt
2
Nutrient requirements

• Each species has specific needs for essential
  nutrients
• e.g. vitamin C essential for guinea pigs, not for
  rats
• National Research Council has published detailed
  documents for each species
• Requirements are minimum needs under ad lib /
  maximum growth conditions

3
Nutrient requirements documents for all
species freely available
http//lab.nap.edu/nap-cgi/dis
cover.cgi?termnutrientrequirementsrestricNAPm
wsubmit.x6submit.y11
4
Why to fulfill nutrient requirements?

• Essential needs of specific nutrients for each
  species and each period in life, for maintaining
  good health, and
• For obtaining reliable results

Skin lesions in Wistar rats due to dietary
Vitamin B 6 and B12 deficiency
5
Toxic levels of nutrients

• Influence of methionine on atherosclerosis in
  apoE deficient mice
• 2.2 and 4.4 dietary methionine
• -gttoxic effects
• Zhou Art.Thromb.Vasc.Biol.2001

6
Responsible concentrations

• Purified AIN diet
• Control 0.5 methionine (NRC level)
• Highest level 1.5 methionin
• No toxic effects
• Reliable results
• Good welfare

7
Types of eating digestion

• Rodents practice coprophagia
• Rabbit also coprophagic and is a rear end
  fermentor
• Dog and cat are carnivores
• Sheep and goat are ruminants and front end
  fermentors
• Swine is a omnivore like humans

8
Types of diets used

• Natural ingredient diets made of natural
  ingredients, such as maize gluten, corn oil,
  wheat
• Frequently used
• Composition such that pelleting is possible
• Relatively cheap

Ritskes-Hoitinga et al. 1991
9
Natural-ingredient dietsChow diets

• Standard diets commercially available for each
  species
• Special diets for Growth/maintenance and
  Reproduction
• Composition meets the needs for each species and
  condition more than sufficiently

10
Diet types

• Natural chows
• Chemically defined
• Purified diets

11
Problem with natural ingredient diets??

• Beynen 2001
• Between brand variation
• Between batch variation
• Batch analysis certificate strongly advised

12
Between-brand variation in 9 natural-ingredient
minipig diets
Catalogue values
Ritskes-Hoitinga, Bollen 1999
13
Between-batch variation4 batches of minipig diet
Ritskes-Hoitinga, Bollen 1999
14
Results from feeding10 brands of rodent chows
Ritskes-Hoitinga et al. 1991
15
Variable composition gives variable results 2 yr
tox studies in 5 labs
Haseman 1984, Roe 1994
16
Standardization requires description

• Survey of scientific articles
• Brand name told in 10-15
• Composition shown in 2
• Conclusion
• If diet has no effect, then OK
• If diet has effect, no way to repeat

17
Solution for variation?

• Stick to one batch
• Difficulty limited duration
• Analysis for critical elements in the diet
• Detailed description of diet in scientific
  articles

18
Diet forms

• Full chows in use
• Only diet and water available
• Standard and expanded pellet
• Powdered diets
• Test substances can be mixed
• Diet is wasted
• Special equipment for feeding
• Liquid and colloid diets

19
Measuring diet consumption

• Diet used eating spillage
• Metabolism cage only reliable
• In group housing get averages
• Values calculated or from reports are for
  guidance only

20
Designing special diets

• If one wishes to change the fat content of the
  diet, isocaloric exchange is needed, because,
• Fat contains more calories per gram than
  carbohydrates and protein
• When changing the fat concentration in the diet,
  the energy concentration changes
• A change in fat concentration must be accompanied
  by an exchange with e.g. carbohydrates on the
  basis of calories
• If this is done on the basis of weight, then the
  animals will ingest a different amount of ALL
  nutrients

21
Diet changes

• Dilution effect
• All additions have some
• Energy rich additions are problematic
• Energy rich drinking solution are no different
• Maximum dilution 10-20
• Results in different amounts of feed eaten

22
Feeding types

• Ad libitum. Takes place mostly during dark
• Meals
• Day or night? Usually restricted feeding time
• Restricted feeding
• amount given is limited
• Pair feeding
• Same amount for study and control groups

23
Standardization in relation to biological rhythms

• All processes show circadian rhythms
• Feeding should be in accordance with their
  natural rhythms
• Otherwise disturbed health, well-being and
  results
• More research needed

24
Advantages of restricted feeding

• Animals live longer
• Fewer spontaneous tumors
• In carcinogenicity study
• test compound may decrease appetite -gt
  carcinogenicity of compound may be underestimated
  
• some assessment of diet consumption is necessary
  to find out which is the case

25
Work for food and enrichment

• Hypothesis
• Rats will work ONLY for food they necessarily
  need, provided work intensity is properly set
• Study
• pellets placed in drilled holes of aspen board
• 3 rats (250 g- ) in a cage, 20 week study
• 3 groups
• A B diet enrichment combination (2 doses)
• C ad libitum

26
p lt 0.001
27
Diet problems

• Excessive protein
• Many diets contain 20-28 protein
• Maximum growth with 17 protein
• Suitable protein content for breeding is on 17-20
  
• In long-term studies excessive protein may lead
  to kidney failure

28
Rodent chows influence on nephrocalcinosis

• Kidney calcification in female rats
• Severity increases with higher dietary P levels
• Variance in nephro-calcinosis 0/6 6/6
• Histological scores 0.0 1.3

Ritskes-Hoitinga et al. 1991
29
Diet problems

• Pesticide heavy metal residues
• Most common cause for rejection of a batch (GLP)
• Ref Food and Drug Administration (FDA), 1978,
  Nonclinical Laboratory Studies. Good Laboratory
  Practice Regulations. Fed Regis, Part 2,
  59986-60025.

30
Why animal breeders use high energy diets?

• Scientists buy animals by weight
• Ad libitum feeding with high energy diet -gtrats
  with certain weight fast
• No change visible

31
References

• Quick reference guide on nutrition,
  www.felasa.eu, 2001
• Beynen, Principles of LAS, 2003
• Chwalibog Ritskes, Handbook of LAS, 2004
• Ritskes and Strubbe, The welfare of lab. animals,
  2004
• Ritskes, The laboratory mouse, 2004
• Dietary Restriction, ILSI Press, 1995

32
Pop quiz

• Study on effects of alcohol on longevity
• Rats drink 10 ethanol in water
• What is being studied
• Effect of ethanol?
• Effect of decreased eating?
• Effect of decreased drinking?
• All of the above?