Outbred rats

Outbred stocks are most often used in research projects requiring vigorous, economically priced animals, but in which considerations of specific genotype are of lesser importance.

Outbred stocks are often used in biological assays or in preliminary studies in which techniques are being perfected prior to more detailed studies using inbred strains. These animals are also useful in studies where large bodyweight or good breeding performance is of greater importance than a defined genotype, or in any study where previous experience has shown that they are suitable. Harlan Laboratories' outbred stocks are easily identified by their nomenclature; we follow standardized nomenclature rules. All our stocks are designated with the holder code, for example “Hsd,” followed by the stock abbreviation.
 
Outbred colonies such as Hsd:Sprague Dawley^® SD^® rats are maintained as closed colonies of genetically variable composition. Harlan outbred stocks have a minimum of 200 female breeders to safeguard the outbred integrity. Although individuals of such colonies will tend to be similar, their genotype at a given locus is usually unknown unless the animal is individually typed.

Sprague Dawley^® and SD^® are U.S. registered trademarks of Harlan Laboratories, Inc., Indianapolis, Indiana, USA, and trademarks of Harlan Laboratories, Inc., in the United Kingdom.