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Chapter 2. The Laboratory Animals. Classification of the laboratory mouse. Kingdom- Animalia Phylum – Cordata Subphylum – Vertebrata Order – Rodentia Family – Muridae Genus – mus Species - musculus.
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Chapter 2 The Laboratory Animals
Classification of the laboratory mouse • Kingdom- Animalia • Phylum – Cordata • Subphylum – Vertebrata • Order – Rodentia • Family – Muridae • Genus – mus • Species - musculus
Animals within in a family have more in common than those in an order and those with the same genus are more related than those in a family. • The scientific name includes genus and species and is written in Italics. • For example : Musmusculus
Scientific names given by the taxonomic system do not include breeds, strains, or varieties which can be seen in different domesticated animals and pets. • The laboratory strains of animals now in use were developed from wild species through selected breedings of many generations. They resemble the wild ancestors but exhibit differences.
The MouseMusMusculus • Smallest of the common laboratory animals and is in the greatest demand. • Small size • Rapid reproduction • High position in the evolutionary scale • Pregnancy lasts 20 days • Average 11 per litter
The RatRattusnorvegicus • Widely used is the albino Norway rat, Rattusnorvegicus • Five basic strains • Long-Evans • Osborne-Mendel • Sherman • Sprague-Dawley • Wistar
The Rat • Primarily nocturnal • Does not have gall bladder • Cannot vomit • Does not cease growing • Were used in nutrition research when researchers realized their similarities to larger monogastric (one stomach) animals and humans
The Guinea PigCaviaporcellus • Has no tail • Main Strains – English, Abyssinian and Peruvian • English – short haired and usually white • Peruvian – long, fine hair • Abyssinian – short and rough haired
The Guinea Pig • Order- Rodentia • Herbivorous • Larger than rat, smaller than rabbit • Requires vitamin C • Pregnancy 65-70 days • Newborn eat dry feed and experiments have shown they can be raised without milk
The RabbitOryctolaguscuniculus • 27 different breeds • Polish rabbit – 1.7 kg • Flemish giant – 9 kg • Order – Lagamorpha • Herbivorous, mostly rouphage • Practice coprophagy (eating feces) by eating directly from the anus soft feces excreted during the night • They are able to obtain vitamins which are made in the lower intestinal tract • Most commonly used is the New Zealand White breed 4 to 5 kg
The HamsterMesocricetusauratus • Most commonly used the Golden or Syrian Hamster • Mature weight 120 grams • Short tails • Cheek pouches • Extended scrotum • Pregnancy lasts 16 days
The Hamster • Females can have babies starting at one month of age • They can store food in cheek pouches and females hide young in these pouches • Can hibernate when temperatures are below 48 F • Housed individually because they can fight • Only litter mates can be housed together
The Gerbil • Fourteen different species • Genus – meriones • Resemble rat and mouse but are small and have a hairy tail • Can go days without water • Urine only a few drops a day and feces are very dry
The Gerbil • Gerbils mate for life, and if a mate dies, they do not accept another mate • Paired at early age • Certain populations can have epileptic-like seizures or convulsions • Caused by excitement or sudden changes in environment