Genetics and control of avian diseases.

This paper discusses the main principles involved in applying genetic resistance to the control of avian infectious diseases, and the actual and potential importance of this approach to disease control. The principles are considered, with illustrative examples, under the following headings: (1) mechanisms of resistance, including virus receptors, interferon, macrophages, immune responses, hormones and body temperature, (2) recognition of resistance, (3) inheritance of resistance, including simple and polygenic control, (4) selection for resistance, including testing for genetic variability, comparison of exposure methods, selection methods and correlations between resistance and other traits.