a group of organisms. They come from a particular source which shares a set of distinguishing characteristics.

In Arabian horses, it has the old Bedouin meaning, in which the strain, or family, traces back in time to a certain mare. It may descend from a mare of a famous breeder, or a mare with an unusual trait or characteristic—such as the "old, well-trained mare of Jedran" or whoever, or a dark mare, or even a filly which had been nursed by a donkey. Only if the family is very strong, and bred to stallions of the same bloodlines, would a strain continually retain a certain type. In other words, the strain remains the same through all generations—if the original mare was Maneghi, so would all her descendants be of that strain, regardless of the many strains represented in the rest of the pedigree, or their differences in type.

a mutation of a certain cultivar selected for an improved characteristic and vegetatively propagated by grafting

a mutation of a variety that has been selected and propagated for an improved characteristic

A genetically related bloodline possessing distinguishing characteristics such as type, color, or coat, and the ability to pass the characteristics to the offspring.

A group of birds within a variety that has been bred by one person or firm for some time and has more or less uniform characteristics and capabilities.

Refers to a group of mice that are bred within a closed colony in order to maintain certain defining characteristics. Strains can be inbred or non-inbred.

A group of animals of known ancestry maintained by a planned inbreeding mating system; generally with some distinguishing characteristics.

A flock of related chickens selectively bred by one person or organization for so long that the offspring have become uniform in appearance or production.