The inclusion of Russell and Burch's Three Rs (replacement, reduction and refinement) in guidelines, codes of practice and law reflects their current position as the guiding principles of ethical assessment of research involving animals. This article explores some activities within the contemporary livestock industry that constitute the experimental use of animals on a local and global scale. The elucidation of correlated responses during trait selection in genetic improvement programs provides one example of experiments occurring within the commercial livestock industry. This experimentation is largely conducted without scrutiny of its conformity to the Three Rs. Experimentation to improve the management of the livestock industry is consistent with the principle of refinement, and experimentation to increase productivity per unit of livestock is consistent with the principle of reduction; however, experimentation to increase total livestock production conflicts with the principle of replacement. Some approaches regarding the appraisal of the ethics of research involving animals, which could avoid arbitrary boundaries associated with the location or purpose of experimentation, are considered together with the relationship between experimentation and other anthropogenic impacts on animals.