Feeding level influences genetic parameters for performance traits in pigs

Abstract

<p>Selection for performance traits is assumed to influence underlying physiological mechanisms, although these changes are not always fully understood. Knowledge about physiological changes may be used to optimise selection strategies for different production and market systems. One way in achieving this is by incorporating information on growth models into breeding programs. The concept of the linear-plateau model has been used in a number of growth models for some time (eg. De Greef, 1992). This concept provides an explanation why pigs differ in growth performance at a given feed intake level depending on their potential for lean meat growth (eg Whittemore, 1986).</p> <p>Selection experiments comparing <i>ad libitum</i> versus restricted feeding systems indicate that restricted feeding improves feed efficiency by favouring lean meat deposition over fat deposition. In addition, pigs selected under restricted feeding had higher growth rate, larger feed intake and lower backfat measurements under <i>ad libitum</i> feeding (e.g. McPhee <i>et al.</i>, 1988; Cameron and Curran, 1995). Genetic parameters obtained from commercial pig populations provide partial support for these genetic relationships (Hermesch <i>et al.</i>, 1999). The development of electronic feeders allows testing of siblings on different feeding levels in the same environment. This data structure enables estimation of heritabilities for performance traits over varying feed intake levels. It also allows investigation of the effect of different feeding levels on genetic parameters for performance traits.</p>