Sir

The recent call by the Nuffield Council on Bioethics (“UK panel urges animal researchers to go public” Nature 435, 392; 2005) for scientists to discuss more openly the use of animals in experiments should start with farm animals. During their lives, most commercial livestock are subject to experimentation at several levels: the individual farm; the national flock or herd; and the global livestock industry. Indeed, at a more basic level, a farm's day-to-day and year-to-year refinement of animal-management practices and business activities is itself scientific, experimental and involves animals.

Commercial livestock are subject to experimentation at several levels: the farm, the national flock or herd and the global livestock industry. Ian G. Colditz

At the individual farm level, genetic improvement programmes provide one example of animal experimentation through collection of data on pedigree and on individual performance such as body weight and milk production. Another example is collection of blood for serology, on the farm or at the point of slaughter, to test hypotheses on disease epidemiology.

What benefits might flow from a broader appreciation of commercial farms' dependence on farm-based animal experimentation within their enterprise and more broadly across their industry?

First, experimental practices, especially genetic improvement programmes, can have welfare consequences that deserve our attention (see W. M. Rauw et al. Livest. Prod. Sci. 56, 15–33 1998). These can be beneficial, for example when animals are selected for calving ease. They can also be harmful, for example in broiler chickens whose legs are weakened by selection for fast growth rate.

Second, the discussion may help illuminate the nature of human–animal relationships and potentially reduce the stigma associated with use of animals in universities and research institutes.