Towards operational definitions of robustness that rely on biology : nutrition

Abstract

This paper explores some of the key issues related to the derivation of operational definitions of robustness: the capacity of an animalto adapt to environmental challenges. Single trait definitions of robustness, although easy to measure, do not capture all of theadaptive response of the animal. A meta-analysis of the responses in the secretion of milk components to changes in energy inputshows clearly that no one component reflects the overall biological response to the nutritional challenge. For this, multi-trait definitionsof robustness are needed, and it is important to make the distinction between biological characteristics and performance measures.It is possible to make the more complex, multi-trait, definitions of robustness operational by extracting the biological componentsfrom performance measures and combining them in a biological way. This 2-step approach is illustrated by 1) the use ofdifferential smoothing to extract milk yield disturbances, 2) the derivation of a degree of infection measured from different componentsof mastitis indicators. The methods used were designed to be general and thus have the potential to provide operational definitionsof robustness that can be applied in the field.