Lab Animal Nutrition

 

Laboratory animal Nutrition

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     INTRODUCTION

• Nutrient requirements change during stages of life cycle especially response to growth , pregnancy, lactation.
• Housing types can also effect the amounts of nutrients needed in diets for example laboratory rodents maintained in either galvanized cages may have a lower dietary requirements for zinc.
• Bcz zinc available in faeces and cage materials.
• These animals ingest bedding or other non food materials this may provide an unintended source of some nutrients or toxins.
•  In rat and mouse most of microbial activity is in colon, and many of the microbially produced nutrients are not available to the host unless faeces are consumed.
• Prevention of coprophagy may require an increase in the nutrient conc. that must be supplied by the diet.

Aspects of feeding

• When rats were given the choice between various diets providing energy from different sources, the rats chose carbohydrate rich diets in the evening hours, and fat rich diets just before the start of resting period

Group housing

• Housing and husbandry conditions can influences both amount of food animals ingest, and the animals feeding patterns
• Individually housed mice of both sexes were found to have higher food intake than mice housed in groups of two, four or eight per cage.
• Mice housed individually or at two per cage had higher body weight and body weight variability than other groups.

Dietary restriction

• Number of studies indicated that restricting the calorie intake of laboratory animals may have beneficial effects on lifespan, incidence and severity of degenerative diseases
•  It is important to achieve calorie restriction of test animals without producing unintended nutrient deficiencies.
• Ex:- adlibitum feeding can result in kidney degeneration in rodents, whereas food restriction prevent kidney degeneration completely.

 

Formulation of diet types

• Choice of ingredients will be influenced by the species to be fed and the experimental or production objectives.
• Guinea pig (Cavies)
• Birth wt – 91-95 grams,
• Maturity (at 5 month) – 700-750 g and
•    at 15 month 850-1000 g.
• Boar to sow ration is 1:5
• Age to breed is 2.5-3.0 month. 
• Gestation period is 66-72 days. 
• Breeding life is 4-6 months to 2 years.
•  Number of litters/year is 3.
• Protein and Amino Acid-       CP in the diet is 18%.  Thirty percent of protein requirement should come from animal protein sources.
• Lipids-            diet should have 0.4% linoleic acid.  Use of 1% soybean oil in their diet will meet linoleic acid requirement.
• Minerals-        Ca and P in diet should be 1 and 0.4%, respectively.
• Feeding:         diet of guinea pigs can be formulated using cereals, their byproducts, oilseed meals, green and dry roughages, animal protein supplements along minerals and vitamins.  It is better to feed them in pellet form.
• DMI: Daily DMI in adults is 30g (7-8% of body weight).  About 150 ml of water is needed by an adult daily.  Newborn animals can consume semisolid and solid food immediately, although weaning is followed around 3 weeks of age.
• Target nutrient conc. must take into account estimated nutrient requirements possible nutrient losses during manufacturing and storage (NRC 1975) bioavailability of nutrients in the ingredients and potential nutrient interactions.
• Wastage is problem with some types of diets, which may be disadvantage if quantitative intake is to measured.

Requirement of Vitamin C in guinea pig

• G. pigs are the only non primates’ which have dietary need of vit-C. 
• So they are good model for vit-C studies. 
• Because of small size and tameness they have long been used for experiments.
• Vitamins-        ascorbic acid is dietary essential.  Due to lack of enzyme L-gulunolactone dehydrogenase. 
• Requirement is 0.5 mg/100g body wt.  As this vitamin is readily oxidized, concentration in stock diet should be much more (6-8 times).

Digestive physiology of guinea pig

• Guinea pig is a simple stomached animal which is lined with glandular epithelium
• It has large semicircular caecum with numerous lateral pouches
• In caecum synthesis of B vitamins and indispensible a.a.s oocur by microorganisms and recycling of intestinal contents by coprophagy

Data on feed consumption

• Growing guinea pig-20-30 g/ day
• Adult guinea pig-30-50g/day
• Pregnant and lactating guinea pigs-40-60 g  (depending upon litter size and season)
• Dry matter consumption is reduced during hot summer
• Maintenance energy requirements-136KCal ME/BW kg^0.75
• Energy requirements for growth -2.8-3.5 Kcal ME/g of feed containing 10% moisture

Feeding of guinea pigs

• Newborn animals can consume semisolid and solid food immediately
• Weaning is followed at around 3 weeks of age
• Guinea pigs normally gain 5-7g/day during rapid growth period when allowed to eat feed ad libitum
• Growth slows after 2 mths and maturity is reached at about 5 mths (700-750g)
• Weight gain can continue untill 12-15 mths of age (850-1000g)

Feeding of hamsters

• Hamsters can fed commercial rat chow.
• Because of their broad muzzle, they are unable to eat through wire hopper feeders.
• So hamster feed placed directly on floor of cages.
• Hamsters carry food in their food in their cheek pounches to their preferred location.
• They tend to set aside an area of the cage for urination and defecation.

Data on feed consumption

• Daily feed consumption (g)                              10-15
• Daily water consumption (ml)                          9-12
• Recommended environmental temperature 21-24⁰C
• Recommended environmental RH                   40-60%

Feeding of Gerbils

• Gerbils tend to eliminate very small amount of wastes, so cage usually clean weekly
• Feeding with commercial a rodent chow is adequate.
• The diet may be supplemented with small amount of sun flower seeds and clean fresh vegetables.
• Adlibitum feeding should be avoided to prevent obesity.

Data on feed consumption

• Daily feed consumption (g)                                               5-7
• Daily water consumption (ml)                                         4
• Recommended environmental temperature               18-22⁰C
• Recommended environmental RH                                 45-50%
• Adult body weight male 46-131gm female                  50-55gm

Feeding of Ferrets

• Commercial ferret chow is available, or cat chow may be fed if it contains protein content of at least 30%.
• Feed is often given in large, heavy bowls placed on cage floor.
• The bowls must be made of indestructible material heavy enough to not be easily tipped over.
• Water can also be provided in heavy bowls.
• Daily feed consumption (g)                                 140-190
• Daily water consumption (ml)                              75-100
• Recommended environmental temperature   39-64⁰C
• Recommended environmental RH                      40-65%
• Avg. adult body weight(kg) male 1-2  female 0.6-0.9kg
• 
  

Rats and mice:

• They are mostly used in nutritional and toxicological studies.
• Nutrient requirement:
• Protein-CP content of diet 18%.  EAAS are HALLVIMPTT.  To satisfy EAAS 30% dietary protein should come animal source.  Whole egg protein supplies nearly optimum amount of AAS.
• Energy – 3000 kcal/kg.
• Fat-5% in diet is recommended to meet the linoleic acid requirement in the diet (1%).
• CHO’s –they are required for normal energy production.
• CF-no absolute requirement of CF. however 5-6% CF is better for better digestive efficiency.

Minerals and vitamins:

About 15 elements are thought to be essential.

• These animals have habbit of coprophagy, so deficiency of B-complex and vit-K rarely exists.
• Feeding-dry powder, pellets or wet mash.  Pellets are better as they do not get soiled with bedding and dropping.
• Formulation- it can be done by using cereals, legumes, oil cakes, animal protein supplements, oils, minerals and vitamin supplements.  Fish meal should be used after autoclaving as it may be contaminated with salmonella.
• DMI- daily rat and mouse is average 15 g, respectively.  Sometimes purified diets are fed to rats and mouse for conducting specific nutritional experiments.

Breeds-

• Black rat (Rattus Rattus), Norway rat (Rattus Norvegicus), Brown rat (Rattus Norvegicus), Albino rat.

General Information:

• 1.         Adult Weight- 190-200G.
• 2.         Wt at birth-(4-5 g).
• 3.         Weaning age- 21 days.
• 4.         Gestation- 21 days.
• 5.         Age at 1st liter-93-111 days.
• 6.         Life span-2-3 years.
• 7.         No of litters in life time-5-7/rat.
• 8.         Productive life in females-480-512 days.
• 9.         Can make all Vit.C required by them but extra Vit.C good for them.
• 10.       Grind their teeth together to maintain proper length and sharpness.
• 11.       Cannot vomit or burp due to a flap in the stomach that covers the oesophagus.  Wild rats are hesitant to try new food but domestic rat not upto that extent
• 12.       Omnivorous
• 13.       Wild rats eat nuts, seed, grains, vegetables, meats, worms, eggs, dead animals, frogs, fish, reptiles birds, mammals-predatory, high req. of nutrient from animal source.
• 14.       Do no need salt lick (needed by herbivores)
• 15.       Protein:  14-15%, Energy: 3.8-4.1 k Cal ME/g
• 16.       Quality of Protein: HALL VIMPTT.
• 17.       25-30% dietary protein through animal protein
• 18.       Nursing females need a high protein diet 24%
• 19.       Linoleic acid 0.6% of diet
• 20.       FAT     5%

Fatty acid deficiency:

12-18 weeks after weaning

• The symptoms are
• 1.         Reduced growth, Scaling of skin.
• 2.         Thickness of skin reduced
• 3.         Roughening of thinning of hairs
• 4.         Reproductive failure
• 5.         Necrosis of tail

    Maintenance Energy:

• Adult rat          114 Kcal ME/W ^0.75 kg
• Growing, pregnant & Lactating: Requirement high
• Fat rats:           15% lower requirement
• Resting heat metabolism per Kg^0.75 is  higher in working and producing animals than non-producing animals
• Nursing females will consume 2-4 times more energy
• Pregnant rats need 10-30% more energy and will eat 10-20% more food or 20-30% more during the first days of gestation increasing up to 140% by day 16-18 of gestation.

Requirement for compounded feeds for Mice and rats (BIS requirements)

Characteristics (% by weight)	Requirements
Moisture	10
CP	24
EE	5
CF	6
Total ash	9
AIA	1
Calcium	0.6
Phosphorus	0.3
Choline (mg/kg)	1100

 

Concluding remarks

• When carrying research using animals, it is challenge to feed them in such a way that their health and welfare is maintained and results are reliable and reproducible.
• To do this it require nutritional and behavioural knowledge.
• Much more research is needed in to how different feeding methods can be used to as enrichment in order to improve laboratory animal welfare.