Description of a growth model: The linear-plateau model

Feed costs are a major cost component of pig production and the optimal use of feed for production is therefore of high importance in an economic and sustainable pig industry. The amount of food eaten by the growing pig is used for maintenance and growth which includes lean meat as well as fat growth. The aim in pig production is to produce lean meat most efficiently which is achieved by optimising fat and lean deposition together with feed intake. In breeding programs selection for efficient lean meat growth has focussed on selection for growth rate, lean meat percentage and feed conversion ratio mostly recorded under ad libitum feeding. However, this selection emphasis has led to a decrease in feed intake which ultimately is limiting growth rate. Examples of proposals to counterbalance reduction in food intake are the proposals by Krieter (1986) to put more emphasis on growth rate, and the suggestion by Brandt (1987) to define an index which does not lead to a change in feed intake. An alternative to these suggestions might be to incorporate knowledge from growth models in breeding decisions. One growth model which is used extensively world wide is the linear-plateau model. This concept is also used in the "Technisch Model Varkensvoeding" (TMV, 1994) (TMV model) developed in The Netherlands. Based on this model the effect of differences in parameters of the linear-plateau model on protein and lipid deposition as well as the traditional performance traits growth rate, lean meat percentage and feed efficiency are illustrated.